COMPANHIA DE SANEAMENTO BASICO DO ESTADO DE SAO PAULO-SABESP (SEC Filing Page | XBRL Cloud Viewer | XBRL Instance)

Line	Label	Object Class	Period Type	Balance	Report ElementName
1	00000001 - Document - Document and Entity Information	Network	*	*	http://sabesp.com.br/role/DocumentAndEntityInformation
2	Implied Table	Table	*	*	implied:Table
3	Document And Entity Information	Abstract			SBS:DocumentAndEntityInformationAbstract
4	Entity Registrant Name	Concept (Text/String)	For Period		dei:EntityRegistrantName
5	Entity Central Index Key	Concept (CIK Number)	For Period		dei:EntityCentralIndexKey
6	Document Type	Concept (Submission Type)	For Period		dei:DocumentType
7	Document Period End Date	Concept (Date)	For Period		dei:DocumentPeriodEndDate
8	Amendment Flag	Concept (Yes/No)	For Period		dei:AmendmentFlag
9	Current Fiscal Year End Date	Concept (Month/Day)	For Period		dei:CurrentFiscalYearEndDate
10	Is Entity a Well-known Seasoned Issuer?	Concept (Yes/No)	For Period		dei:EntityWellKnownSeasonedIssuer
11	Is Entity a Voluntary Filer?	Concept (Yes/No)	For Period		dei:EntityVoluntaryFilers
12	Is Entity's Reporting Status Current?	Concept (Yes/No)	For Period		dei:EntityCurrentReportingStatus
13	Entity Filer Category	Concept (Filer Category)	For Period		dei:EntityFilerCategory
14	Entity Emerging Growth Company	Concept (Yes/No)	For Period		dei:EntityEmergingGrowthCompany
15	Entity Shell Company	Concept (Yes/No)	For Period		dei:EntityShellCompany
16	Entity Common Stock, Shares Outstanding	Concept (Shares)	As Of		dei:EntityCommonStockSharesOutstanding
17	Document Fiscal Period Focus	Concept (Fiscal Period)	For Period		dei:DocumentFiscalPeriodFocus
18	Document Fiscal Year Focus	Concept (Year)	For Period		dei:DocumentFiscalYearFocus
19	00000002 - Statement - Statements of Financial Position	Network	*	*	http://sabesp.com.br/role/StatementsOfFinancialPosition
20	Implied Table	Table	*	*	implied:Table
21	Statement of financial position [abstract]	Abstract			ifrs-full:StatementOfFinancialPositionAbstract
22	Assets	Abstract			ifrs-full:AssetsAbstract
23	Current assets	Abstract			ifrs-full:CurrentAssetsAbstract
24	Cash and cash equivalents	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalents
25	Trade receivables	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentTradeReceivables
26	Accounts receivable from related parties	Concept (Monetary)	As Of	Debit	ifrs-full:AmountsReceivableRelatedPartyTransactions
27	Inventories	Concept (Monetary)	As Of	Debit	ifrs-full:Inventories
28	Restricted cash	Concept (Monetary)	As Of	Debit	ifrs-full:RestrictedCashAndCashEquivalents
29	Recoverable taxes	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentTaxAssets
30	Other receivables	Concept (Monetary)	As Of	Debit	ifrs-full:OtherCurrentReceivables
31	Total current assets	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentAssets
32	Noncurrent assets	Abstract			ifrs-full:NoncurrentAssetsAbstract
33	Trade receivables	Concept (Monetary)	As Of	Debit	ifrs-full:NoncurrentTradeReceivables
34	Accounts receivable from related parties	Concept (Monetary)	As Of	Debit	ifrs-full:NoncurrentReceivablesDueFromRelatedParties
35	Escrow deposits	Concept (Monetary)	As Of	Debit	ifrs-full:LongtermDeposits
36	Water National Agency - ANA	Concept (Monetary)	As Of	Debit	SBS:WaterNationalAgencyNoncurrent
37	Other receivables	Concept (Monetary)	As Of	Debit	ifrs-full:OtherNoncurrentReceivables
38	Investments	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentAccountedForUsingEquityMethod
39	Investment properties	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentProperty
40	Contract asset	Concept (Monetary)	As Of	Debit	ifrs-full:NoncurrentContractAssets
41	Intangible assets	Concept (Monetary)	As Of	Debit	ifrs-full:IntangibleAssetsOtherThanGoodwill
42	Property, plant and equipment	Concept (Monetary)	As Of	Debit	ifrs-full:PropertyPlantAndEquipment
43	Total noncurrent assets	Concept (Monetary)	As Of	Debit	ifrs-full:NoncurrentAssets
44	Total assets	Concept (Monetary)	As Of	Debit	ifrs-full:Assets
45	Liabilities and equity	Abstract			ifrs-full:EquityAndLiabilitiesAbstract
46	Current liabilities	Abstract			ifrs-full:CurrentLiabilitiesAbstract
47	Trade payables and contractors	Concept (Monetary)	As Of	Credit	ifrs-full:TradeAndOtherPayablesToTradeSuppliers
48	Current portion of long-term borrowings and financing	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentPortionOfLongtermBorrowings
49	Accrued payroll and related taxes	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentProvisionsForEmployeeBenefits
50	Taxes and contributions	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentTaxLiabilities
51	Interest on capital	Concept (Monetary)	As Of	Credit	ifrs-full:DividendPayables
52	Provisions	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentProvisions
53	Services payable	Concept (Monetary)	As Of	Credit	ifrs-full:OtherShorttermProvisions
54	Public-Private Partnership - PPP	Concept (Monetary)	As Of	Credit	SBS:PublicPrivatePartnershipCurrent
55	Program Contract Commitments	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentContractLiabilities
56	Other liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:OtherCurrentLiabilities
57	Total current liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentLiabilities
58	Noncurrent liabilities	Abstract			ifrs-full:NoncurrentLiabilitiesAbstract
59	Borrowings and financing	Concept (Monetary)	As Of	Credit	ifrs-full:LongtermBorrowings
60	Deferred income tax and social contribution	Concept (Monetary)	As Of	Credit	SBS:DeferredIncomeTaxAndSocialContribution
61	Deferred Cofins and PASEP	Concept (Monetary)	As Of	Credit	SBS:DeferredCOFINSAndPASEP
62	Provisions	Concept (Monetary)	As Of	Credit	ifrs-full:NoncurrentProvisions
63	Pension obligations	Concept (Monetary)	As Of	Credit	SBS:PensionObligations
64	Public-Private Partnership - PPP	Concept (Monetary)	As Of	Credit	SBS:PublicPrivatePartnershipNoncurrent
65	Program Contract Commitments	Concept (Monetary)	As Of	Credit	ifrs-full:NoncurrentContractLiabilities
66	Other liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:OtherNoncurrentLiabilities
67	Total noncurrent liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:NoncurrentLiabilities
68	Total liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:Liabilities
69	Equity	Abstract			ifrs-full:EquityAbstract
70	Capital stock	Concept (Monetary)	As Of	Credit	ifrs-full:IssuedCapital
71	Earnings reserves	Concept (Monetary)	As Of	Credit	ifrs-full:OtherReserves
72	Other comprehensive loss	Concept (Monetary)	As Of	Credit	ifrs-full:AccumulatedOtherComprehensiveIncome
73	Total equity	Concept (Monetary)	As Of	Credit	ifrs-full:Equity
74	Total equity and liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:EquityAndLiabilities
75	00000003 - Statement - Income Statement	Network	*	*	http://sabesp.com.br/role/IncomeStatement
76	Implied Table	Table	*	*	implied:Table
77	Profit or loss [abstract]	Abstract			ifrs-full:IncomeStatementAbstract
78	Net operating income	Concept (Monetary)	For Period	Credit	ifrs-full:Revenue
79	Cost of services	Concept (Monetary)	For Period	Debit	ifrs-full:CostOfSales
80	Gross profit	Concept (Monetary)	For Period	Credit	ifrs-full:GrossProfit
81	Selling expenses	Concept (Monetary)	For Period	Debit	ifrs-full:SellingExpense
82	Allowance for doubtful accounts	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLoss
83	Administrative expenses	Concept (Monetary)	For Period	Debit	ifrs-full:AdministrativeExpense
84	Other operating income (expenses), net	Concept (Monetary)	For Period	Credit	ifrs-full:OtherOperatingIncomeExpense
85	Equity in results of investments in affiliaties	Concept (Monetary)	For Period	Credit	SBS:EquityInResultsOfInvestmentsInAffiliaties
86	Profit from operations before finance income (expenses) and income tax and social contribution	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossFromContinuingOperations
87	Financial expenses	Concept (Monetary)	For Period	Debit	ifrs-full:FinanceCosts
88	Financial revenues	Concept (Monetary)	For Period	Credit	ifrs-full:FinanceIncome
89	Exchange result, net	Concept (Monetary)	For Period	Credit	ifrs-full:NetForeignExchangeGain
90	Financial result, net	Concept (Monetary)	For Period	Credit	SBS:FinanceIncomeExpenseNet
91	Profit before income tax and social contribution	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossBeforeTax
92	Income tax and social contribution	Abstract			ifrs-full:MajorComponentsOfTaxExpenseIncomeAbstract
93	Current	Concept (Monetary)	For Period	Debit	ifrs-full:CurrentTaxExpenseIncome
94	Deferred	Concept (Monetary)	For Period	Debit	ifrs-full:DeferredTaxExpenseIncome
95	Income tax and social contribution, total	Concept (Monetary)	For Period	Debit	SBS:IncomeTaxAndSocialContribution
96	Profit for the year	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
97	Earnings per share - basic and diluted (in reais)	Concept (Share)	For Period		ifrs-full:BasicAndDilutedEarningsLossPerShare
98	00000004 - Statement - Statements of Comprehensive Income	Network	*	*	http://sabesp.com.br/role/StatementsOfComprehensiveIncome
99	Implied Table	Table	*	*	implied:Table
100	Profit or loss [abstract]	Abstract			ifrs-full:IncomeStatementAbstract
101	Profit for the year	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
102	Other comprehensive income (loss)	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncome
103	Items which will not be subsequently reclassified to the income statement:	Abstract			ifrs-full:ComponentsOfOtherComprehensiveIncomeThatWillNotBeReclassifiedToProfitOrLossNetOfTaxAbstract
104	Actuarial gains and (losses) on defined benefit plans	Concept (Monetary)	For Period	Debit	ifrs-full:ActuarialGainsLossesArisingFromChangesInFinancialAssumptionsNetDefinedBenefitLiabilityAsset
105	Total comprehensive income for the year	Concept (Monetary)	For Period	Credit	ifrs-full:ComprehensiveIncome
106	00000005 - Statement - Statements of Changes in Equity	Network	*	*	http://sabesp.com.br/role/StatementsOfChangesInEquity
107	Statement of changes in equity [table]	Table	*	*	ifrs-full:StatementOfChangesInEquityTable
108	Components of equity [axis]	Axis			ifrs-full:ComponentsOfEquityAxis
109	Equity [member]	Member			ifrs-full:EquityMember
110	Capital stock	Member			ifrs-full:IssuedCapitalMember
111	Legal reserve	Member			ifrs-full:StatutoryReserveMember
112	Investment reserve	Member			SBS:InvestmentReserveMember
113	Additional dividend proposed	Member			SBS:AdditionalDividendProposedMember
114	Retained earnings	Member			ifrs-full:RetainedEarningsMember
115	Other comprehensive loss	Member			ifrs-full:AccumulatedOtherComprehensiveIncomeMember
116	Statement of changes in equity [line items]	LineItems			ifrs-full:StatementOfChangesInEquityLineItems
117	Beginning balance	Concept (Monetary)	As Of	Credit	ifrs-full:Equity
118	Net income for the year	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
119	Actuarial gains (losses)	Concept (Monetary)	For Period	Debit	ifrs-full:ActuarialGainsLossesArisingFromChangesInFinancialAssumptionsNetDefinedBenefitLiabilityAsset
120	Total comprehensive income for the year	Concept (Monetary)	For Period	Credit	ifrs-full:ComprehensiveIncome
121	Legal reserve	Concept (Monetary)	For Period	Credit	SBS:LegalReserve
122	Investments reserve capitalized	Concept (Monetary)	For Period	Credit	SBS:InvestmentsReserveCapitalised
123	Interest on capital (R$1.0240 per share)	Concept (Monetary)	For Period	Debit	SBS:InterestExpenseOnCapital1
124	Interest on capital (R$0.87539 per share)	Concept (Monetary)	For Period	Debit	SBS:InterestExpenseOnCapital2
125	Interest on capital (R$0.9851 per share)	Concept (Monetary)	For Period	Debit	SBS:InterestExpenseOnCapital3
126	2015 additional proposed dividends, approved (R$0.0330 per share)	Concept (Monetary)	For Period	Debit	SBS:AdditionalDividendsProposedApproved1
127	2016 additional proposed dividends, approved (R$0.09176 per share)	Concept (Monetary)	For Period	Debit	SBS:AdditionalDividendsProposedApproved2
128	2016 additional proposed dividends, approved (R$0.07833 per share)	Concept (Monetary)	For Period	Debit	SBS:AdditionalDividendsProposedApproved3
129	Additional proposed dividends	Concept (Monetary)	For Period	Debit	ifrs-full:DividendsRecognisedAsDistributionsToOwnersOfParentRelatingToCurrentYear
130	Withholding income tax on interest on capital attributable as minimum mandatory dividends	Concept (Monetary)	For Period	Credit	SBS:WithholdingIncomeTaxOnInterestOnCapitalAttributableAsMinimumMandatoryDividends
131	Transfer to investments reserve	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughTransferToStatutoryReserve
132	Ending balance	Concept (Monetary)	As Of	Credit	ifrs-full:Equity
133	00000006 - Statement - Statements of Cash Flows	Network	*	*	http://sabesp.com.br/role/StatementsOfCashFlows
134	Implied Table	Table	*	*	implied:Table
135	Statement of cash flows [abstract]	Abstract			ifrs-full:StatementOfCashFlowsAbstract
136	Cash flow from operating activities	Abstract			ifrs-full:CashFlowsFromUsedInOperatingActivitiesAbstract
137	Profit before income tax and social contribution	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossBeforeTax
138	Adjustments for:	Abstract			ifrs-full:AdjustmentsForReconcileProfitLossAbstract
139	Depreciation and amortization	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForDepreciationAndAmortisationExpense
140	Residual value of property, plant and equipment, intangible assets and investment properties written-off	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForLossesGainsOnDisposalOfNoncurrentAssets
141	Bad debt expense, net of recoveries	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForImpairmentLossReversalOfImpairmentLossRecognisedInProfitOrLoss
142	Agreement signed with the municipality of Guarulhos	Concept (Monetary)	For Period	Credit	SBS:AdjustmentsForGuarulhosAgreement
143	Provisions and inflation adjustment	Concept (Monetary)	For Period	Debit	SBS:ProvisionsAndInflationAdjustment
144	Pension plan liabilities - early reduction (curtailment)	Concept (Monetary)	For Period	Credit	ifrs-full:PastServiceCostNetDefinedBenefitLiabilityAsset
145	Interest calculated on borrowings and financing payable	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForFinanceCosts
146	Inflation adjustment and exchange gains (losses) on borrowings and financing	Concept (Monetary)	For Period	Credit	SBS:InflationAdjustmentAndExchangeGainsLossesOnBorrowingsAndFinancing
147	Interest and inflation adjustment on liabilities	Concept (Monetary)	For Period	Credit	SBS:InterestAndInflationAdjustmentOnLiabilities
148	Interest and inflation adjustment on assets	Concept (Monetary)	For Period	Debit	SBS:InterestAndInflationAdjustmentOnAssets
149	Finance charges from customers	Concept (Monetary)	For Period	Debit	SBS:FinanceChargesFromCustomers
150	Margin of fair value on intangible assets arising from concession	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossRecognisedOnExchangingConstructionServicesForIntangibleAsset2011
151	Provision for Consent Decree (TAC)	Concept (Monetary)	For Period	Credit	SBS:ProvisionForConsentDecree
152	Share of profit of investees	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughChangeInEquityOfSubsidiaries
153	Provision from S�o Paulo agreement	Concept (Monetary)	For Period	Credit	SBS:ProvisionFromSaoPauloAgreement
154	Provision for pension plan - Sabesprev Mais	Concept (Monetary)	For Period	Debit	ifrs-full:PostemploymentBenefitExpenseDefinedContributionPlans
155	Pension obligations	Concept (Monetary)	For Period	Debit	ifrs-full:PostemploymentBenefitExpenseDefinedBenefitPlans
156	Other adjustments	Concept (Monetary)	For Period	Debit	ifrs-full:OtherAdjustmentsToReconcileProfitLoss
157	Total adustments	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForReconcileProfitLoss
158	Changes in assets	Abstract			SBS:IncreaseDecreaseInAssetsAbstract
159	Trade receivables	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForDecreaseIncreaseInTradeAccountReceivable
160	Accounts receivable from related parties	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForDecreaseIncreaseInOtherOperatingReceivables
161	Inventories	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForDecreaseIncreaseInInventories
162	Recoverable taxes	Concept (Monetary)	For Period	Debit	SBS:AdjustmentsForRecoverableTaxes
163	Escrow deposits	Concept (Monetary)	For Period	Debit	SBS:AdjustmentsForIncreaseDecreaseInEscrowDeposits
164	Other receivables	Concept (Monetary)	For Period	Debit	SBS:AdjustmentsForDecreaseIncreaseInOtherReceivables
165	Changes in liabilities	Abstract			SBS:IncreaseDecreaseInLiabilitiesAbstract
166	Trade payables and contractors	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForIncreaseDecreaseInTradeAccountPayable
167	Services payable	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForIncreaseDecreaseInOtherOperatingPayables
168	Accrued payroll and related taxes	Concept (Monetary)	For Period	Debit	SBS:AdjustmentsForDecreaseIncreaseInAccruedPayrollTaxes
169	Taxes and contributions payable	Concept (Monetary)	For Period	Debit	SBS:AdjustmentsForDecreaseIncreaseInTaxesAndContributionsPayable
170	Deferred Cofins/PASEP	Concept (Monetary)	For Period	Debit	SBS:AdjustmentsForDecreaseIncreaseInDeferredCofinsPASEP
171	Provisions	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForProvisions
172	Pension obligations	Concept (Monetary)	For Period	Debit	SBS:AdjustmentsForPensionObligations
173	Other liabilities	Concept (Monetary)	For Period	Debit	ifrs-full:AdjustmentsForIncreaseDecreaseInOtherLiabilities
174	Cash generated from operations	Concept (Monetary)	For Period		ifrs-full:CashFlowsFromUsedInOperations
175	Interest paid	Concept (Monetary)	For Period	Credit	ifrs-full:InterestPaidClassifiedAsOperatingActivities
176	Income tax and social contribution paid	Concept (Monetary)	For Period	Credit	ifrs-full:IncomeTaxesPaidRefundClassifiedAsOperatingActivities
177	Net cash generated from operating activities	Concept (Monetary)	For Period		ifrs-full:CashFlowsFromUsedInOperatingActivities
178	Cash flows from investing activities	Abstract			ifrs-full:CashFlowsFromUsedInInvestingActivitiesAbstract
179	Acquisition of contract asset and intangible	Concept (Monetary)	For Period	Credit	ifrs-full:PurchaseOfIntangibleAssetsClassifiedAsInvestingActivities
180	Restricted cash	Concept (Monetary)	For Period	Debit	ifrs-full:CashFlowsFromUsedInDecreaseIncreaseInRestrictedCashAndCashEquivalents
181	Investment increase	Concept (Monetary)	For Period	Debit	ifrs-full:OtherInflowsOutflowsOfCashClassifiedAsInvestingActivities
182	Purchase of property, plant and equipment	Concept (Monetary)	For Period	Credit	ifrs-full:PurchaseOfPropertyPlantAndEquipmentClassifiedAsInvestingActivities
183	Dividends received	Concept (Monetary)	For Period	Debit	ifrs-full:DividendsReceivedClassifiedAsInvestingActivities
184	Net cash used in investing activities	Concept (Monetary)	For Period	Debit	ifrs-full:CashFlowsFromUsedInInvestingActivities
185	Cash flows from financing activities	Abstract			ifrs-full:CashFlowsFromUsedInFinancingActivitiesAbstract
186	Borrowings and financing	Abstract			SBS:BorrowingsAndFinancingAbstract
187	Proceeds from loans	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromBorrowingsClassifiedAsFinancingActivities
188	Payment of loans	Concept (Monetary)	For Period	Credit	ifrs-full:RepaymentsOfBorrowingsClassifiedAsFinancingActivities
189	Payment of interest on capital	Concept (Monetary)	For Period	Credit	ifrs-full:DividendsPaidClassifiedAsFinancingActivities
190	Public-Private Partnership - PPP	Concept (Monetary)	For Period	Credit	ifrs-full:PaymentsOfFinanceLeaseLiabilitiesClassifiedAsFinancingActivities
191	Program Contract Commitments	Concept (Monetary)	For Period	Credit	SBS:ProgramContractCommitments
192	Net cash used in financing activities	Concept (Monetary)	For Period	Debit	ifrs-full:CashFlowsFromUsedInFinancingActivities
193	Increase in cash and cash equivalents	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseInCashAndCashEquivalents
194	Represented by :	Abstract			SBS:CashAndCashEquivalentsRepresentedByAbstract
195	Cash and cash equivalents at the beginning of the year	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalents
196	Cash and cash equivalents at the end of the year	Concept (Monetary)	As Of	Debit	ifrs-full:CashAndCashEquivalents
197	Increase in cash and cash equivalents	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseInCashAndCashEquivalents
198	00000007 - Disclosure - 1. Operations	Network	*	*	http://sabesp.com.br/role/Operations
199	Implied Table	Table	*	*	implied:Table
200	Operations	Abstract			SBS:OperationsAbstract
201	Operations	Concept (Text Block (HTML))	For Period		SBS:DisclosureOfOperationsExplanatory
202	00000008 - Disclosure - 2. Basis of preparation and presentation of the financial statements	Network	*	*	http://sabesp.com.br/role/BasisOfPreparationAndPresentationOfFinancialStatements
203	Implied Table	Table	*	*	implied:Table
204	Basis Of Preparation And Presentation Of Financial Statements	Abstract			SBS:BasisOfPreparationAndPresentationOfFinancialStatementsAbstract
205	Basis of preparation and presentation of the financial statements	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfBasisOfPreparationOfFinancialStatementsExplanatory
206	00000009 - Disclosure - 3. Summary of Significant Accounting Policies	Network	*	*	http://sabesp.com.br/role/SummaryOfSignificantAccountingPolicies
207	Implied Table	Table	*	*	implied:Table
208	Summary Of Significant Accounting Policies	Abstract			SBS:SummaryOfSignificantAccountingPoliciesAbstract
209	Summary of Significant Accounting Policies	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfSummaryOfSignificantAccountingPoliciesExplanatory
210	00000010 - Disclosure - 4. Changes in accounting practices and disclosures	Network	*	*	http://sabesp.com.br/role/ChangesInAccountingPracticesAndDisclosures
211	Implied Table	Table	*	*	implied:Table
212	Changes In Accounting Practices And Disclosures	Abstract			SBS:ChangesInAccountingPracticesAndDisclosuresAbstract
213	Changes in accounting practices and disclosures	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfInitialApplicationOfStandardsOrInterpretations
214	00000011 - Disclosure - 5. Risk Management	Network	*	*	http://sabesp.com.br/role/RiskManagement
215	Implied Table	Table	*	*	implied:Table
216	Risk Management	Abstract			SBS:RiskManagementAbstract
217	Risk Management	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfMarketRiskExplanatory
218	00000012 - Disclosure - 6. Key accounting estimates and judgments	Network	*	*	http://sabesp.com.br/role/KeyAccountingEstimatesAndJudgments
219	Implied Table	Table	*	*	implied:Table
220	Key Accounting Estimates And Judgments	Abstract			SBS:KeyAccountingEstimatesAndJudgmentsAbstract
221	Key accounting estimates and judgments	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfAccountingJudgementsAndEstimatesExplanatory
222	00000013 - Disclosure - 7. Cash and cash equivalents	Network	*	*	http://sabesp.com.br/role/CashAndCashEquivalents
223	Implied Table	Table	*	*	implied:Table
224	Cash and cash equivalents [abstract]	Abstract			ifrs-full:CashAndCashEquivalentsAbstract
225	Cash and cash equivalents	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfCashAndCashEquivalentsExplanatory
226	00000014 - Disclosure - 8. Restricted cash	Network	*	*	http://sabesp.com.br/role/RestrictedCash
227	Implied Table	Table	*	*	implied:Table
228	Restricted Cash	Abstract			SBS:RestrictedCashAbstract
229	Restricted cash	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfRestrictedCashAndCashEquivalentsExplanatory
230	00000015 - Disclosure - 9. Trade receivables	Network	*	*	http://sabesp.com.br/role/TradeReceivables
231	Implied Table	Table	*	*	implied:Table
232	Trade Receivables	Abstract			SBS:TradeReceivablesAbstract
233	Trade receivables	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfTradeAndOtherReceivablesExplanatory
234	00000016 - Disclosure - 10. Related-Party Balances and Transactions	Network	*	*	http://sabesp.com.br/role/Related-partyBalancesAndTransactions
235	Implied Table	Table	*	*	implied:Table
236	Related-party Balances And Transactions	Abstract			SBS:RelatedpartyBalancesAndTransactionsAbstract
237	Related-Party Balances and Transactions	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfRelatedPartyExplanatory
238	00000017 - Disclosure - 11. Water National Agency - ANA	Network	*	*	http://sabesp.com.br/role/WaterNationalAgency-Ana
239	Implied Table	Table	*	*	implied:Table
240	Water National Agency - Ana	Abstract			SBS:WaterNationalAgencyAnaAbstract
241	Water National Agency - ANA	Concept (Text Block (HTML))	For Period		SBS:DisclosureOfWaterNationalAgencyExplanatory
242	00000018 - Disclosure - 12. Investments	Network	*	*	http://sabesp.com.br/role/Investments
243	Implied Table	Table	*	*	implied:Table
244	Investments	Abstract			SBS:InvestmentsAbstract
245	Investments	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfInvestmentsAccountedForUsingEquityMethodExplanatory
246	00000019 - Disclosure - 13. Investment properties	Network	*	*	http://sabesp.com.br/role/InvestmentProperties
247	Implied Table	Table	*	*	implied:Table
248	Investment Properties	Abstract			SBS:InvestmentPropertiesAbstract
249	Investment properties	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfInvestmentPropertyExplanatory
250	00000020 - Disclosure - 14. Contract asset	Network	*	*	http://sabesp.com.br/role/ContractAsset
251	Implied Table	Table	*	*	implied:Table
252	Contract Asset	Abstract			SBS:ContractAssetAbstract
253	Contract asset	Concept (Text Block (HTML))	For Period		ifrs-full:ExplanationOfSignificantChangesInContractAssetsAndContractLiabilitiesExplanatory
254	00000021 - Disclosure - 15. Intangible assets	Network	*	*	http://sabesp.com.br/role/IntangibleAssets
255	Implied Table	Table	*	*	implied:Table
256	Intangible Assets	Abstract			SBS:IntangibleAssetsAbstract
257	Intangible assets	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfServiceConcessionArrangementsExplanatory
258	00000022 - Disclosure - 16. Property, plant and equipment	Network	*	*	http://sabesp.com.br/role/PropertyPlantAndEquipment
259	Implied Table	Table	*	*	implied:Table
260	Property, plant and equipment [abstract]	Abstract			ifrs-full:PropertyPlantAndEquipmentAbstract
261	Property, plant and equipment	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfPropertyPlantAndEquipmentExplanatory
262	00000023 - Disclosure - 17. Borrowings and financing	Network	*	*	http://sabesp.com.br/role/BorrowingsAndFinancing
263	Implied Table	Table	*	*	implied:Table
264	Borrowings And Financing	Abstract			SBS:BorrowingsAndFinancingAbstract
265	Borrowings and financing	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfBorrowingsExplanatory
266	00000024 - Disclosure - 18. Taxes recoverable/payable	Network	*	*	http://sabesp.com.br/role/TaxesRecoverablepayable
267	Implied Table	Table	*	*	implied:Table
268	Taxes Recoverablepayable	Abstract			SBS:TaxesRecoverablepayableAbstract
269	Taxes recoverable/payable	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfTaxReceivablesAndPayablesExplanatory
270	00000025 - Disclosure - 19. Deferred taxes and contributions	Network	*	*	http://sabesp.com.br/role/DeferredTaxesAndContributions
271	Implied Table	Table	*	*	implied:Table
272	Deferred Taxes And Contributions	Abstract			SBS:DeferredTaxesAndContributionsAbstract
273	Deferred taxes and contributions	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfDeferredTaxesExplanatory
274	00000026 - Disclosure - 20. Provisions	Network	*	*	http://sabesp.com.br/role/Provisions
275	Implied Table	Table	*	*	implied:Table
276	Provisions [abstract]	Abstract			ifrs-full:ProvisionsAbstract
277	Provisions	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfProvisionsExplanatory
278	00000027 - Disclosure - 21. Employees benefits	Network	*	*	http://sabesp.com.br/role/EmployeesBenefits
279	Implied Table	Table	*	*	implied:Table
280	Employees Benefits	Abstract			SBS:EmployeesBenefitsAbstract
281	Employees benefits	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfEmployeeBenefitsExplanatory
282	00000028 - Disclosure - 22. Services payable	Network	*	*	http://sabesp.com.br/role/ServicesPayable
283	Implied Table	Table	*	*	implied:Table
284	Services Payable	Abstract			SBS:ServicesPayableAbstract
285	Services payable	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfOtherLiabilitiesExplanatory
286	00000029 - Disclosure - 23. Knowledge retention program	Network	*	*	http://sabesp.com.br/role/KnowledgeRetentionProgram
287	Implied Table	Table	*	*	implied:Table
288	Knowledge Retention Program	Abstract			SBS:KnowledgeRetentionProgramAbstract
289	Knowledge retention program	Concept (Text Block (HTML))	For Period		SBS:DisclosureOfKnowledgeRetentionProgramExplanatory
290	00000030 - Disclosure - 24. Equity	Network	*	*	http://sabesp.com.br/role/Equity
291	Implied Table	Table	*	*	implied:Table
292	Equity	Abstract			ifrs-full:EquityAbstract
293	Equity	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfIssuedCapitalExplanatory
294	00000031 - Disclosure - 25. Earnings per share	Network	*	*	http://sabesp.com.br/role/EarningsPerShare
295	Implied Table	Table	*	*	implied:Table
296	Earnings per share [abstract]	Abstract			ifrs-full:EarningsPerShareAbstract
297	Earnings per share	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfEarningsPerShareExplanatory
298	00000032 - Disclosure - 26. Operating segment information	Network	*	*	http://sabesp.com.br/role/OperatingSegmentInformation
299	Implied Table	Table	*	*	implied:Table
300	Operating Segment Information	Abstract			SBS:OperatingSegmentInformationAbstract
301	Operating segment information	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfOperatingSegmentsExplanatory
302	00000033 - Disclosure - 27. Insurance	Network	*	*	http://sabesp.com.br/role/Insurance
303	Implied Table	Table	*	*	implied:Table
304	Insurance	Abstract			SBS:InsuranceAbstract
305	Insurance	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfInsuranceContractsExplanatory
306	00000034 - Disclosure - 28. Operating revenue	Network	*	*	http://sabesp.com.br/role/OperatingRevenue
307	Implied Table	Table	*	*	implied:Table
308	Operating Revenue	Abstract			SBS:OperatingRevenueAbstract
309	Operating revenue	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfRevenueExplanatory
310	00000035 - Disclosure - 29. Operating costs and expenses	Network	*	*	http://sabesp.com.br/role/OperatingCostsAndExpenses
311	Implied Table	Table	*	*	implied:Table
312	Operating Costs And Expenses	Abstract			SBS:OperatingCostsAndExpensesAbstract
313	Operating costs and expenses	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfExpensesByNatureExplanatory
314	00000036 - Disclosure - 30. Financial Income (Expenses)	Network	*	*	http://sabesp.com.br/role/FinancialIncomeExpenses
315	Implied Table	Table	*	*	implied:Table
316	Financial Income	Abstract			SBS:FinancialIncomeExpensesAbstract
317	Financial Income (Expenses)	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFinanceIncomeExpenseExplanatory
318	00000037 - Disclosure - 31. Other operating income (expenses), net	Network	*	*	http://sabesp.com.br/role/OtherOperatingIncomeExpensesNet
319	Implied Table	Table	*	*	implied:Table
320	Other Operating Income Expenses Net	Abstract			SBS:OtherOperatingIncomeExpensesNetAbstract
321	Other operating income (expenses), net	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfOtherOperatingIncomeExpenseExplanatory
322	00000038 - Disclosure - 32. Commitments	Network	*	*	http://sabesp.com.br/role/Commitments
323	Implied Table	Table	*	*	implied:Table
324	Commitments	Abstract			SBS:CommitmentsAbstract
325	Commitments	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfCommitmentsExplanatory
326	00000039 - Disclosure - 33. Supplemental cash flow information	Network	*	*	http://sabesp.com.br/role/SupplementalCashFlowInformation
327	Implied Table	Table	*	*	implied:Table
328	Supplemental Cash Flow Information	Abstract			SBS:SupplementalCashFlowInformationAbstract
329	Supplemental cash flow information	Concept (Text Block (HTML))	For Period		SBS:DisclosureOfSupplementalCashFlowInformationExplanatory
330	00000040 - Disclosure - 34. Events after the reporting period	Network	*	*	http://sabesp.com.br/role/EventsAfterReportingPeriod
331	Implied Table	Table	*	*	implied:Table
332	Events After Reporting Period	Abstract			SBS:EventsAfterReportingPeriodAbstract
333	Events after the reporting period	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfEventsAfterReportingPeriodExplanatory
334	00000041 - Disclosure - 3. Summary of Significant Accounting Policies (Policies)	Network	*	*	http://sabesp.com.br/role/SummaryOfSignificantAccountingPoliciesPolicies
335	Implied Table	Table	*	*	implied:Table
336	Summary Of Significant Accounting Policies	Abstract			SBS:SummaryOfSignificantAccountingPoliciesPoliciesAbstract
337	Cash and cash equivalents	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyToDetermineComponentsOfCashAndCashEquivalents
338	Financial assets and liabilities	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForFinancialInstrumentsExplanatory
339	Operating income	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForRecognitionOfRevenue
340	Trade receivables and allowance for doubtful accounts	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForTradeAndOtherReceivablesExplanatory
341	Inventories	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForMeasuringInventories
342	Investment properties	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForInvestmentPropertyExplanatory
343	Property, plant and equipment	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForPropertyPlantAndEquipmentExplanatory
344	Intangible assets	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForServiceConcessionArrangementsExplanatory
345	Impairment of non-financial assets	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForImpairmentOfNonfinancialAssetsExplanatory
346	Trade accounts payable and contractors	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForTradeAndOtherPayablesExplanatory
347	Borrowings and financing	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForBorrowingsExplanatory
348	Borrowing costs	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForBorrowingCostsExplanatory
349	Payroll, related charges and contributions	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForEmployeeBenefitsExplanatory
350	Profit sharing	Concept (Text Block (HTML))	For Period		SBS:DescriptionOfAccountingPolicyForProfitSharingExplanatory
351	Provisions, legal obligations, escrow deposits, contingent assets	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForProvisionsExplanatory
352	Environmental costs	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForEnvironmentRelatedExpenseExplanatory
353	Income taxes - current and deferred	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForIncomeTaxExplanatory
354	Taxes on revenues	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForTaxesOtherThanIncomeTaxExplanatory
355	Pension obligations	Concept (Text Block (HTML))	For Period		SBS:DescriptionOfAccountingPolicyForPensionObligationsExplanatory
356	Financial revenues and expenses	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForFinanceIncomeAndCostsExplanatory
357	Leases	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForLeasesExplanatory
358	Other current and noncurrent assets and liabilities	Concept (Text Block (HTML))	For Period		SBS:DescriptionOfAccountingPolicyForOtherCurrentAndNoncurrentAssetsAndLiabilitiesExplanatory
359	Dividends and interest on capital	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForDividendsExplanatory
360	Present value adjustment	Concept (Text Block (HTML))	For Period		SBS:DescriptionOfAccountingPolicyForPresentValueAdjustmentExplanatory
361	Segment information	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForSegmentReportingExplanatory
362	Translation into foreign currency	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfAccountingPolicyForForeignCurrencyTranslationExplanatory
363	00000042 - Disclosure - 4. Changes in accounting practices and disclosures (Tables)	Network	*	*	http://sabesp.com.br/role/ChangesInAccountingPracticesAndDisclosuresTables
364	Implied Table	Table	*	*	implied:Table
365	Changes In Accounting Practices And Disclosures	Abstract			SBS:ChangesInAccountingPracticesAndDisclosuresTablesAbstract
366	New standards, amendments and interpretations, adopted	Concept (Text Block (HTML))	For Period		SBS:SummaryOfNewAccountingStandardsAmendmentsAndInterpretationsAdoptedTableTextBlock
367	Effects of new accounting standard	Concept (Text Block (HTML))	For Period		SBS:SummaryOfEffectsOfNewAccountingStandardTableTextBlock
368	New standards, amendments and interpretations, not yet effective	Concept (Text Block (HTML))	For Period		ifrs-full:DescriptionOfExpectedImpactOfInitialApplicationOfNewStandardsOrInterpretations
369	00000043 - Disclosure - 5. Risk Management (Tables)	Network	*	*	http://sabesp.com.br/role/RiskManagementTables
370	Implied Table	Table	*	*	implied:Table
371	Risk Management	Abstract			SBS:RiskManagementTablesAbstract
372	Exposure to exchange risk	Concept (Text Block (HTML))	For Period		SBS:SummaryOfExposureToExchangeRiskTableTextBlock
373	Borrowing and financing variable interest rate	Concept (Text Block (HTML))	For Period		SBS:SummaryOfBorrowingAndFinancingVariableInterestRateTableTextBlock
374	Credit rating	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfCreditRiskExplanatory
375	Credit information of banks	Concept (Text Block (HTML))	For Period		SBS:SummaryOfCreditInformationOfBanksTableTextBlock
376	Liquidity risk	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfLiquidityRiskExplanatory
377	Capital management	Concept (Text Block (HTML))	For Period		SBS:SummaryOfCapitalManagementTableTextBlock
378	Fair value of financial instruments	Concept (Text Block (HTML))	For Period		ifrs-full:DisclosureOfFairValueOfFinancialInstrumentsExplanatory
379	Financial liabilities	Concept (Text Block (HTML))	For Period		SBS:SummaryOfFinancialLiabilitiesTableTextBlock
380	00000044 - Disclosure - 7. Cash and cash equivalents (Tables)	Network	*	*	http://sabesp.com.br/role/CashAndCashEquivalentsTables
381	Implied Table	Table	*	*	implied:Table
382	Cash And Cash Equivalents	Abstract			SBS:CashAndCashEquivalentsTablesAbstract
383	Cash and cash equivalents	Concept (Text Block (HTML))	For Period		SBS:SummaryOfCashAndCashEquivalentsTableTextBlock
384	00000045 - Disclosure - 8. Restricted cash (Tables)	Network	*	*	http://sabesp.com.br/role/RestrictedCashTables
385	Implied Table	Table	*	*	implied:Table
386	Restricted Cash	Abstract			SBS:RestrictedCashTablesAbstract
387	Restricted cash	Concept (Text Block (HTML))	For Period		SBS:SummaryOfRestrictedCashTableTextBlock
388	00000046 - Disclosure - 9. Trade receivables (Tables)	Network	*	*	http://sabesp.com.br/role/TradeReceivablesTables
389	Implied Table	Table	*	*	implied:Table
390	Trade Receivables	Abstract			SBS:TradeReceivablesTablesAbstract
391	Financial position	Concept (Text Block (HTML))	For Period		SBS:SummaryOfFinancialPositionTableTextBlock
392	Wholesale customers	Concept (Text Block (HTML))	For Period		SBS:SummaryOfWholesaleCustomersTableTextBlock
393	Aging of trade receivables	Concept (Text Block (HTML))	For Period		SBS:SummaryOfAgingOfTradeReceivablesTableTextBlock
394	Allowance for doubtful accounts	Concept (Text Block (HTML))	For Period		SBS:SummaryOfTradeReceivableAllowanceForDoubtfulAccountsTableTextBlock
395	Reconciliation of estimated/historic losses of income	Concept (Text Block (HTML))	For Period		SBS:SummaryOfReconciliationOfEstimatedLossesOfIncomeTableTextBlock
396	00000047 - Disclosure - 10. Related-Party Balances and Transactions (Tables)	Network	*	*	http://sabesp.com.br/role/Related-partyBalancesAndTransactionsTables
397	Implied Table	Table	*	*	implied:Table
398	Related-party Balances And Transactions	Abstract			SBS:RelatedpartyBalancesAndTransactionsTablesAbstract
399	Accounts receivable, interest on capital payable, revenue and expenses with the Sao Paulo State Government	Concept (Text Block (HTML))	For Period		SBS:SummaryOfAccountsReceivableInterestOnCapitalPayableRevenueAndExpensesWithGovernmentTableTextBlock
400	Loan agreement through credit facility	Concept (Text Block (HTML))	For Period		SBS:SummaryOfLoanAgreementThroughCreditFacilityTableTextBlock
401	00000048 - Disclosure - 12. Investments (Tables)	Network	*	*	http://sabesp.com.br/role/InvestmentsTables
402	Implied Table	Table	*	*	implied:Table
403	Investments	Abstract			SBS:InvestmentsTablesAbstract
404	Summary of the investees' financial statements and equity interest	Concept (Text Block (HTML))	For Period		SBS:SummaryOfInvesteesFinancialStatementsAndEquityInterestTableTextBlock
405	00000049 - Disclosure - 13. Investment properties (Tables)	Network	*	*	http://sabesp.com.br/role/InvestmentPropertiesTables
406	Implied Table	Table	*	*	implied:Table
407	Investment Properties	Abstract			SBS:InvestmentPropertiesTablesAbstract
408	Investment properties	Concept (Text Block (HTML))	For Period		SBS:SummaryOfInvestmentPropertiesTableTextBlock
409	00000050 - Disclosure - 14. Contract asset (Tables)	Network	*	*	http://sabesp.com.br/role/ContractAssetTables
410	Implied Table	Table	*	*	implied:Table
411	Contract Asset	Abstract			SBS:ContractAssetTablesAbstract
412	Contract asset	Concept (Text Block (HTML))	For Period		SBS:SummaryOfContractAssetsTableTextBlock
413	00000051 - Disclosure - 15. Intangible assets (Tables)	Network	*	*	http://sabesp.com.br/role/IntangibleAssetsTables
414	Implied Table	Table	*	*	implied:Table
415	Intangible Assets	Abstract			SBS:IntangibleAssetsTablesAbstract
416	Statement of financial position details	Concept (Text Block (HTML))	For Period		SBS:SummaryOfFinancialPositionDetailsTableTextBlock
417	Changes in intangible assets	Concept (Text Block (HTML))	For Period		SBS:SumamryOfChangesInIntangibleAssetsTableTextBlock
418	Liabilities assumed	Concept (Text Block (HTML))	For Period		SBS:SummaryOfLiabilitiesAssumedTableTextBlock
419	00000052 - Disclosure - 16. Property, plant and equipment (Tables)	Network	*	*	http://sabesp.com.br/role/PropertyPlantAndEquipmentTables
420	Implied Table	Table	*	*	implied:Table
421	Property Plant And Equipment	Abstract			SBS:PropertyPlantAndEquipmentTablesAbstract
422	Statement of financial position details	Concept (Text Block (HTML))	For Period		SBS:SummaryOfPropertyPlantAndEquipmentTableTextBlock
423	Changes in property, plant, and equipment	Concept (Text Block (HTML))	For Period		SBS:SummaryOfChangesInPropertyPlantAndEquipmentTableTextBlock
424	00000053 - Disclosure - 17. Borrowings and financing (Tables)	Network	*	*	http://sabesp.com.br/role/BorrowingsAndFinancingTables
425	Implied Table	Table	*	*	implied:Table
426	Borrowings And Financing	Abstract			SBS:BorrowingsAndFinancingTablesAbstract
427	Borrowings and financing outstanding	Concept (Text Block (HTML))	For Period		SBS:SummaryOfBorrowingsAndFinancingOutstandingTableTextBlock
428	Borrowings terms	Concept (Text Block (HTML))	For Period		SBS:SummaryOfBorrowingsTermsTableTextBlock
429	Borrowings payment schedule	Concept (Text Block (HTML))	For Period		SBS:SummaryOfBorrowingsPaymentScheduleTableTextBlock
430	Changes in borrowings	Concept (Text Block (HTML))	For Period		SBS:SummaryOfChangesInBorrowingsTableTextBlock
431	Borrwing costs amortization	Concept (Text Block (HTML))	For Period		SBS:SummaryOfBorrwingCostsAmortisationTableTextBlock
432	Funding	Concept (Text Block (HTML))	For Period		SBS:SummaryOfFundingTableTextBlock
433	Borrowings and financing - Credit Limits	Concept (Text Block (HTML))	For Period		SBS:SummaryOfBorrowingsAndFinancingCreditLimitedTableTextBlock
434	00000054 - Disclosure - 18. Taxes recoverable/payable (Tables)	Network	*	*	http://sabesp.com.br/role/TaxesRecoverablepayableTables
435	Implied Table	Table	*	*	implied:Table
436	Taxes Recoverablepayable	Abstract			SBS:TaxesRecoverablepayableTablesAbstract
437	Current tax assets	Concept (Text Block (HTML))	For Period		SBS:SummaryOfCurrentTaxAssetsTableTextBlock
438	Current tax liabilities	Concept (Text Block (HTML))	For Period		SBS:SummaryOfCurrentTaxLiabilitiesTableTextBlock
439	00000055 - Disclosure - 19. Deferred taxes and contributions (Tables)	Network	*	*	http://sabesp.com.br/role/DeferredTaxesAndContributionsTables
440	Implied Table	Table	*	*	implied:Table
441	Deferred Taxes And Contributions	Abstract			SBS:DeferredTaxesAndContributionsTablesAbstract
442	Deferred taxes	Concept (Text Block (HTML))	For Period		SBS:SummaryOfDeferredTaxesTableTextBlock
443	Realization	Concept (Text Block (HTML))	For Period		SBS:SummaryOfRealizationOfDeferredTaxesTableTextBlock
444	Changes	Concept (Text Block (HTML))	For Period		SBS:SummaryOfChangesInDeferredTaxesTableTextBlock
445	Reconciliation of the effective tax rate	Concept (Text Block (HTML))	For Period		SBS:SummaryOfReconciliationOfEffectiveTaxRateTableTextBlock
446	00000056 - Disclosure - 20. Provisions (Tables)	Network	*	*	http://sabesp.com.br/role/ProvisionsTables
447	Implied Table	Table	*	*	implied:Table
448	Provisions	Abstract			SBS:ProvisionsTablesAbstract
449	Lawsuits and proceedings that resulted in provisions	Concept (Text Block (HTML))	For Period		SBS:SummaryOfLawsuitsAndProceedingsThatResultedInProvisionsTableTextBlock
450	Changes in provisions	Concept (Text Block (HTML))	For Period		SBS:SummaryOfChangesInProvisionsTableTextBlock
451	Lawsuits deemed as contingent liabilities	Concept (Text Block (HTML))	For Period		SBS:SummaryOfLawsuitsDeemedAsContingentLiabilitiesTableTextBlock
452	00000057 - Disclosure - 21. Employees benefits (Tables)	Network	*	*	http://sabesp.com.br/role/EmployeesBenefitsTables
453	Implied Table	Table	*	*	implied:Table
454	Employees Benefits	Abstract			SBS:EmployeesBenefitsTablesAbstract
455	Pension plan benefits	Concept (Text Block (HTML))	For Period		SBS:SummaryOfPensionPlanBenefitsTableTextBlock
456	(Gains)/losses, due to changes in assumptions	Concept (Text Block (HTML))	For Period		SBS:SummaryOfGainsLossesDueToChangesInAssumptionsTableTextBlock
457	Reconciliation of defined benefit obligations	Concept (Text Block (HTML))	For Period		SBS:SummaryOfReconciliationOfDefinedBenefitObligationsTableTextBlock
458	Fair value of plan	Concept (Text Block (HTML))	For Period		SBS:SummaryOfFairValueOfBenefitPlanTableTextBlock
459	Amounts recognized in income statement	Concept (Text Block (HTML))	For Period		SBS:SummaryOfAmountsRecognizedInIncomeStatementTableTextBlock
460	Benefit plan expenses recognized by employer	Concept (Text Block (HTML))	For Period		SBS:SummaryOfBenefitPlanExpensesRecognizedByEmployerTableTextBlock
461	Actuarial assumptions	Concept (Text Block (HTML))	For Period		SBS:SummaryOfActuarialAssumptionsTableTextBlock
462	Sensitivity analysis of benefit plans	Concept (Text Block (HTML))	For Period		SBS:SummaryOfSensitivityAnalysisOfBenefitPlansTableTextBlock
463	Plan assets	Concept (Text Block (HTML))	For Period		SBS:SummaryOfPlanAssetsTableTextBlock
464	Defined benefit obligation	Concept (Text Block (HTML))	For Period		SBS:SummaryOfDefinedBenefitObligationTableTextBlock
465	Amounts recognized in income statement	Concept (Text Block (HTML))	For Period		SBS:SummaryOfAmountsRecognizedInIncomeStatementFundedPlanTableTextBlock
466	Expense related to defined benefit plan	Concept (Text Block (HTML))	For Period		SBS:SummaryOfExpenseRelatedToDefinedBenefitPlanUnfundedTableTextBlock
467	Main actuarial assumptions used	Concept (Text Block (HTML))	For Period		SBS:SummaryOfMainActuarialAssumptionsUsedTableTextBlock
468	Actuarial assumptions unfunded plan	Concept (Text Block (HTML))	For Period		SBS:SummaryOfActuarialAssumptionsUnfundedPlanTableTextBlock
469	00000058 - Disclosure - 23. Knowledge retention program (Tables)	Network	*	*	http://sabesp.com.br/role/KnowledgeRetentionProgramTables
470	Implied Table	Table	*	*	implied:Table
471	Knowledge Retention Program	Abstract			SBS:KnowledgeRetentionProgramAbstract
472	Knowledge retention program	Concept (Text Block (HTML))	For Period		SBS:SummaryOfKnowledgeRetentionProgramTableTextBlock
473	00000059 - Disclosure - 24. Equity (Tables)	Network	*	*	http://sabesp.com.br/role/EquityTables
474	Implied Table	Table	*	*	implied:Table
475	Equity	Abstract			SBS:EquityTablesAbstract
476	Subscribed and paid-in capital	Concept (Text Block (HTML))	For Period		SBS:SummaryOfSubscribedAndPaidinCapitalTableTextBlock
477	Distribution of earnings	Concept (Text Block (HTML))	For Period		SBS:SummaryOfDistributionOfEarningsTableTextBlock
478	Allocation of profit	Concept (Text Block (HTML))	For Period		SBS:SummaryOfAllocationOfProfitTableTextBlock
479	Other comprehensive loss	Concept (Text Block (HTML))	For Period		SBS:SummaryOfOtherComprehensiveLossTableTextBlock
480	00000060 - Disclosure - 25. Earnings per share (Tables)	Network	*	*	http://sabesp.com.br/role/EarningsPerShareTables
481	Implied Table	Table	*	*	implied:Table
482	Earnings Per Share	Abstract			SBS:EarningsPerShareTablesAbstract
483	Earnings per share, basic and diluted	Concept (Text Block (HTML))	For Period		SBS:SummaryOfEarningsPerShareBasicAndDilutedTableTextBlock
484	00000061 - Disclosure - 26. Operating segment information (Tables)	Network	*	*	http://sabesp.com.br/role/OperatingSegmentInformationTables
485	Implied Table	Table	*	*	implied:Table
486	Operating Segment Information	Abstract			SBS:OperatingSegmentInformationTablesAbstract
487	Operating segment information	Concept (Text Block (HTML))	For Period		SBS:SummaryOfOperatingSegmentInformationTableTextBlock
488	Impacts on gross operating income and costs	Concept (Text Block (HTML))	For Period		SBS:SummaryOfImpactsOnGrossOperatingRevenueAndCostsTableTextBlock
489	00000062 - Disclosure - 27. Insurance (Tables)	Network	*	*	http://sabesp.com.br/role/InsuranceTables
490	Implied Table	Table	*	*	implied:Table
491	Insurance	Abstract			SBS:InsuranceTablesAbstract
492	Insurance coverage	Concept (Text Block (HTML))	For Period		SBS:SummaryOfInsuranceCoverageTableTextBlock
493	00000063 - Disclosure - 28. Operating revenue (Tables)	Network	*	*	http://sabesp.com.br/role/OperatingRevenueTables
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497	Reconciliation between gross operating income and net operating income	Concept (Text Block (HTML))	For Period		SBS:SummaryOfReconciliationOfGrossOperatingRevenueAndNetOperatingRevenue
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502	00000065 - Disclosure - 30. Financial Income (Expenses) (Tables)	Network	*	*	http://sabesp.com.br/role/FinancialIncomeExpensesTables
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504	Financial Income Expenses	Abstract			SBS:FinancialIncomeExpensesTablesAbstract
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506	00000066 - Disclosure - 31. Other operating income (expenses), net (Tables)	Network	*	*	http://sabesp.com.br/role/OtherOperatingIncomeExpensesNetTables
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510	00000067 - Disclosure - 32. Commitments (Tables)	Network	*	*	http://sabesp.com.br/role/CommitmentsTables
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513	Commitments	Concept (Text Block (HTML))	For Period		SBS:SummaryOfCommitmentsTableTextBlock
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518	00000069 - Disclosure - 1. Operations (Details Narrative)	Network	*	*	http://sabesp.com.br/role/OperationsDetailsNarrative
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529	Intangible assets concentrated in the municipality of S�o Paulo	Concept (Percent)	For Period		SBS:IntangibleAssetsConcentratedInMunicipalityOfSaoPaulo
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534	00000070 - Disclosure - 4. Changes in accounting practices and disclosures (Details)	Network	*	*	http://sabesp.com.br/role/ChangesInAccountingPracticesAndDisclosuresDetails
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546	00000071 - Disclosure - 4. Changes in accounting practices and disclosures (Details 1)	Network	*	*	http://sabesp.com.br/role/ChangesInAccountingPracticesAndDisclosuresDetails1
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562	Other receivables	Concept (Monetary)	As Of	Debit	ifrs-full:OtherCurrentReceivables
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567	Escrow deposits	Concept (Monetary)	As Of	Debit	ifrs-full:LongtermDeposits
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570	Investments	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentAccountedForUsingEquityMethod
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585	00000074 - Disclosure - 5. Risk Management (Details 1)	Network	*	*	http://sabesp.com.br/role/RiskManagementDetails1
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592	TJLP	Member			SBS:TJLPMember
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597	00000075 - Disclosure - 5. Risk Management (Details 2)	Network	*	*	http://sabesp.com.br/role/RiskManagementDetails2
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606	00000076 - Disclosure - 5. Risk Management (Details 3)	Network	*	*	http://sabesp.com.br/role/RiskManagementDetails3
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611	Banco Santander Brasil S/A	Member			SBS:BancoSantanderBrasilMember
612	Brazilian Federal Savings Bank	Member			SBS:CaixaEconomicaFederalMember
613	Banco Bradesco S/A	Member			SBS:BancoBradescoMember
614	Itau Unibanco Holding S/A	Member			SBS:ItauUnibancoHoldingMember
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618	Moody's	Member			SBS:MoodysMember
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620	SummaryOfRiskManagementLineItems [Line Items]	LineItems			SBS:SummaryOfRiskManagementLineItems
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622	00000077 - Disclosure - 5. Risk Management (Details 4)	Network	*	*	http://sabesp.com.br/role/RiskManagementDetails4
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627	2020	Member			SBS:TwentyTwentyMember
628	2021	Member			SBS:TwentyTwentyOneMember
629	2022	Member			SBS:TwentyTwentyTwoMember
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635	Services payable	Concept (Monetary)	As Of	Credit	ifrs-full:OtherShorttermProvisions
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638	00000078 - Disclosure - 5. Risk Management (Details 5)	Network	*	*	http://sabesp.com.br/role/RiskManagementDetails5
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647	00000079 - Disclosure - 5. Risk Management (Details 6)	Network	*	*	http://sabesp.com.br/role/RiskManagementDetails6
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656	Trade receivables	Concept (Monetary)	As Of	Debit	ifrs-full:TradeReceivables
657	Water National Agency - ANA	Concept (Monetary)	As Of	Debit	SBS:WaterNationalAgencyNoncurrent
658	Other receivables	Concept (Monetary)	As Of	Debit	ifrs-full:OtherReceivables
659	Borrowings and financing	Concept (Monetary)	As Of	Credit	ifrs-full:Borrowings
660	Accounts payables to suppliers and contractors	Concept (Monetary)	As Of	Credit	SBS:AccountsPayablesToSuppliersAndContractors
661	Services payable	Concept (Monetary)	As Of	Credit	ifrs-full:OtherShorttermProvisions
662	Program contract commitments	Concept (Monetary)	As Of	Credit	SBS:ProgramContractCommitment
663	Public-Private Partnership - PPP	Concept (Monetary)	As Of	Credit	SBS:PublicPrivatePartnership
664	00000080 - Disclosure - 5. Risk Management (Details Narrative)	Network	*	*	http://sabesp.com.br/role/RiskManagementDetailsNarrative
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669	Effects on profit for the year before taxes	Concept (Monetary)	For Period	Debit	SBS:EffectsOnProfitForTheYearBeforeTaxes
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673	00000081 - Disclosure - 7. Cash and cash equivalents (Details)	Network	*	*	http://sabesp.com.br/role/CashAndCashEquivalentsDetails
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677	Cash equivalents	Concept (Monetary)	As Of	Debit	ifrs-full:CashEquivalents
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679	00000082 - Disclosure - 7. Cash and cash equivalents (Details Narrative)	Network	*	*	http://sabesp.com.br/role/CashAndCashEquivalentsDetailsNarrative
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692	00000086 - Disclosure - 9. Trade receivables (Details 2)	Network	*	*	http://sabesp.com.br/role/TradeReceivablesDetails2
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707	00000087 - Disclosure - 9. Trade receivables (Details 3)	Network	*	*	http://sabesp.com.br/role/TradeReceivablesDetails3
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716	00000088 - Disclosure - 9. Trade receivables (Details 4)	Network	*	*	http://sabesp.com.br/role/TradeReceivablesDetails4
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720	(Losses)/reversal with state entities - related parties	Concept (Monetary)	For Period	Debit	SBS:ExpenseRecognisedDuringPeriodForBadAndDoubtfulDebtsForRelatedPartyTransactionStateEntitiesRelatedParties
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725	00000089 - Disclosure - 9. Trade receivables (Details Narrative)	Network	*	*	http://sabesp.com.br/role/TradeReceivablesDetailsNarrative
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729	00000092 - Disclosure - 10. Related-Party Balances and Transactions (Details 2)	Network	*	*	http://sabesp.com.br/role/Related-partyBalancesAndTransactionsDetails2
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737	Loan agreement total	Concept (Monetary)	As Of	Debit	SBS:RelatedPartyLoanAgreement
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740	00000094 - Disclosure - 11. Water National Agency - ANA (Details Narrative)	Network	*	*	http://sabesp.com.br/role/WaterNationalAgency-AnaDetailsNarrative
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744	00000095 - Disclosure - 12. Investments (Details)	Network	*	*	http://sabesp.com.br/role/InvestmentsDetails
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752	Attend Ambiental	Member			SBS:AttendAmbientalMember
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760	Dividends distributed	Concept (Monetary)	As Of	Credit	ifrs-full:DividendPayables
761	Profit for the year	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
762	Profit for the year - change in the equity	Concept (Monetary)	For Period	Credit	SBS:ProfitForYearChangeInEquity
763	Investments	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentAccountedForUsingEquityMethod
764	Capital increase	Concept (Monetary)	For Period	Credit	SBS:CapitalIncrease2
765	Dividends distributed - change in the equity	Concept (Monetary)	As Of	Credit	SBS:DividendsDistributedChangeInEquity
766	Equity in the earnings of subsidiaries	Concept (Monetary)	As Of	Credit	SBS:EquityInResultsOfInvestmentsInAffiliates
767	Equity in the earnings of subsidiaries - change in the equity	Concept (Monetary)	As Of	Credit	SBS:EquityInEarningsOfSubsidiariesChangeInEquity
768	Interest percentage	Concept (Percent)	For Period		ifrs-full:ProportionOfOwnershipInterestInJointVenture
769	00000096 - Disclosure - 12. Investments (Details Narrative)	Network	*	*	http://sabesp.com.br/role/InvestmentsDetailsNarrative
770	DisclosureOfInvestmentsTable [Table]	Table	*	*	SBS:DisclosureOfInvestmentsTable
771	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
772	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
773	Annual and Extraordinary Shareholders' Meeting	Member			SBS:AnnualAndExtraordinaryShareholdersMeetingMember
774	Annual and Extraordinary Shareholders' Meeting	Member			SBS:AnnualAndExtraordinaryShareholdersMeeting1Member
775	Saneaqua Mairinque	Member			SBS:SaneaquaMairinqueMember
776	Investment Issuer [Axis]	Axis			invest:InvestmentIssuerAxis
777	Investment Issuer [Domain]	Member			invest:InvestmentIssuerDomain
778	Sesamm	Member			SBS:SesammMember
779	Aguas de Andradina	Member			SBS:AguasDeAndradinaMember
780	Aguas de Castilho	Member			SBS:AguasDeCastilhoMember
781	Saneaqua Mairinque	Member			SBS:SaneaquaMairinqueMember
782	Attend Ambiental	Member			SBS:AttendAmbientalMember
783	Aquapolo Ambiental	Member			SBS:AquapoloAmbientalMember
784	Paulista Geradora de Energia	Member			SBS:PaulistaGeradoraDeEnergiaMember
785	DisclosureOfInvestmentsLineItems [Line Items]	LineItems			SBS:DisclosureOfInvestmentsLineItems
786	Capital stock	Concept (Monetary)	As Of	Credit	ifrs-full:IssuedCapital
787	Capital stock, shares	Concept (Shares)	As Of		dei:EntityCommonStockSharesOutstanding
788	Equity interest	Concept (Percent)	For Period		ifrs-full:ProportionOfOwnershipInterestInJointVenture
789	Other receivables	Concept (Monetary)	As Of	Debit	ifrs-full:OtherReceivables
790	Advance for future capital increase	Concept (Monetary)	As Of	Credit	SBS:AdvanceForFutureCapitalIncrease
791	Capital increase	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughTransfersAndOtherChangesEquity
792	Shares issued	Concept (Shares)	As Of		ifrs-full:NumberOfSharesIssued
793	Minimum mandatory dividends	Concept (Monetary)	For Period	Debit	ifrs-full:DividendsPaid
794	Additional dividends	Concept (Monetary)	For Period	Debit	SBS:AdditionalDividends
795	00000097 - Disclosure - 13. Investment properties (Details)	Network	*	*	http://sabesp.com.br/role/InvestmentPropertiesDetails
796	Implied Table	Table	*	*	implied:Table
797	Investment Properties	Abstract			SBS:InvestmentPropertiesDetailsAbstract
798	Investment properties, beginning	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentProperty
799	Transfers	Concept (Monetary)	For Period	Debit	SBS:TransfersInvestmentProperty
800	Write-offs and disposals	Concept (Monetary)	For Period	Credit	ifrs-full:DisposalsInvestmentProperty
801	Reversal of estimated losses	Concept (Monetary)	For Period		ifrs-full:ReversalOfImpairmentLossRecognisedInProfitOrLossInvestmentProperty
802	Depreciation	Concept (Monetary)	For Period		ifrs-full:DepreciationInvestmentProperty
803	Investment properties, ending	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentProperty
804	00000098 - Disclosure - 13. Investment properties (Details Narrative)	Network	*	*	http://sabesp.com.br/role/InvestmentPropertiesDetailsNarrative
805	Implied Table	Table	*	*	implied:Table
806	Investment Properties	Abstract			SBS:InvestmentPropertiesDetailsNarrativeAbstract
807	Investment properties	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentProperty
808	Investment properties, market value	Concept (Monetary)	As Of	Debit	SBS:InvestmentPropertyMarketValue
809	00000099 - Disclosure - 14. Contract asset (Details)	Network	*	*	http://sabesp.com.br/role/ContractAssetDetails
810	Disclosure of assets recognised from costs to obtain or fulfil contracts with customers [table]	Table	*	*	ifrs-full:DisclosureOfAssetsRecognisedFromCostsToObtainOrFulfilContractsWithCustomersTable
811	Classes of assets [axis]	Axis			ifrs-full:ClassesOfAssetsAxis
812	Assets [member]	Member			ifrs-full:ClassesOfAssetsMember
813	Agreements - equity value	Member			SBS:AgreementsEquityValueMember
814	Agreements - economic value	Member			SBS:AgreementsEconomicValueMember
815	Program contracts	Member			SBS:ProgramContractsMember
816	Services contracts - S�o Paulo	Member			SBS:ServicesContractsSaoPauloMember
817	Software license	Member			SBS:SoftwareLicenseMember
818	Inventories	Member			SBS:InventoryMember
819	Advance to suppliers	Member			SBS:AdvanceToSuppliersMember
820	Disclosure of assets recognised from costs to obtain or fulfil contracts with customers [line items]	LineItems			ifrs-full:DisclosureOfAssetsRecognisedFromCostsToObtainOrFulfilContractsWithCustomersLineItems
821	Contract assets, beginning	Concept (Monetary)	As Of	Debit	ifrs-full:ContractAssets
822	Additions	Concept (Monetary)	For Period	Debit	SBS:AdditionsToContractAssets
823	Contract renewal	Concept (Monetary)	For Period	Credit	SBS:ContractRenewal
824	Transfers of works	Concept (Monetary)	For Period	Credit	SBS:TransfersOfWorks
825	Contract assets, ending	Concept (Monetary)	As Of	Debit	ifrs-full:ContractAssets
826	00000100 - Disclosure - 15. Intangible assets (Details)	Network	*	*	http://sabesp.com.br/role/IntangibleAssetsDetails
827	SummaryOfIntangibleAssetsTable [Table]	Table	*	*	SBS:SummaryOfIntangibleAssetsTable
828	Classes of intangible assets and goodwill [Axis]	Axis			ifrs-full:ClassesOfIntangibleAssetsOtherThanGoodwillAxis
829	Intangible assets other than goodwill [member]	Member			ifrs-full:IntangibleAssetsOtherThanGoodwillMember
830	Agreements - equity value	Member			SBS:AgreementsEquityValueMember
831	Agreements - economic value	Member			SBS:AgreementsEconomicValueMember
832	Program contracts	Member			SBS:ProgramContractsMember
833	Program contracts - commitments	Member			SBS:ProgramContractsCommitmentsMember
834	Services contracts - Sao Paulo	Member			SBS:ServiceContractsCommitmentsMember
835	Software license	Member			SBS:SoftwareLicenseMember
836	SummaryOfIntangibleAssetsLineItems [Line Items]	LineItems			SBS:SummaryOfIntangibleAssetsLineItems
837	Cost	Concept (Monetary)	As Of	Debit	ifrs-full:IntangibleAssetsOtherThanGoodwillCarryingAmountAtCostOfRevaluedAssets
838	Accumulated amortization	Concept (Monetary)	As Of	Credit	SBS:IntangibleAssetsAccumulatedAmortization
839	Net	Concept (Monetary)	As Of	Debit	ifrs-full:IntangibleAssetsOtherThanGoodwill
840	00000101 - Disclosure - 15. Intangible assets (Details 1)	Network	*	*	http://sabesp.com.br/role/IntangibleAssetsDetails1
841	SummaryOfIntangibleAssetsTable [Table]	Table	*	*	SBS:SummaryOfIntangibleAssetsTable
842	Classes of intangible assets and goodwill [Axis]	Axis			ifrs-full:ClassesOfIntangibleAssetsOtherThanGoodwillAxis
843	Intangible assets other than goodwill [member]	Member			ifrs-full:IntangibleAssetsOtherThanGoodwillMember
844	Agreements - equity value	Member			SBS:AgreementsEquityValueMember
845	Agreements - economic value	Member			SBS:AgreementsEconomicValueMember
846	Program contracts	Member			SBS:ProgramContractsMember
847	Program contracts - commitments	Member			SBS:ProgramContractsCommitmentsMember
848	Services contracts - Sao Paulo	Member			SBS:ServiceContractsCommitmentsMember
849	Software license	Member			SBS:SoftwareLicenseMember
850	SummaryOfIntangibleAssetsLineItems [Line Items]	LineItems			SBS:SummaryOfIntangibleAssetsLineItems
851	Intangible assets, beginning	Concept (Monetary)	As Of	Debit	ifrs-full:IntangibleAssetsOtherThanGoodwill
852	Transfers to contract assets	Concept (Monetary)	For Period	Debit	SBS:IncreaseDecreaseThroughTransfersToContractAssets
853	Additions	Concept (Monetary)	For Period	Debit	ifrs-full:AdditionsOtherThanThroughBusinessCombinationsIntangibleAssetsOtherThanGoodwill
854	Contract renewal	Concept (Monetary)	For Period	Debit	SBS:ContractRenewalOfConcessionsArrengements
855	Reversal of estimated losses	Concept (Monetary)	For Period		ifrs-full:ImpairmentLossRecognisedInProfitOrLossIntangibleAssetsOtherThanGoodwill
856	Transfers of works	Concept (Monetary)	For Period	Debit	SBS:IncreaseDecreaseThroughTransfersOfWork
857	Transfers	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseThroughTransfersIntangibleAssetsOtherThanGoodwill
858	Write-offs and disposals	Concept (Monetary)	For Period	Credit	ifrs-full:DisposalsIntangibleAssetsOtherThanGoodwill
859	Amortization	Concept (Monetary)	For Period		ifrs-full:AmortisationIntangibleAssetsOtherThanGoodwill
860	Intangible assets, ending	Concept (Monetary)	As Of	Debit	ifrs-full:IntangibleAssetsOtherThanGoodwill
861	00000102 - Disclosure - 15. Intangible assets (Details 2)	Network	*	*	http://sabesp.com.br/role/IntangibleAssetsDetails2
862	SummaryOfIntangibleAssetsTable [Table]	Table	*	*	SBS:SummaryOfIntangibleAssetsTable
863	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
864	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
865	Alto Tiete	Member			SBS:AltoTieteMember
866	Sao Lourenco	Member			SBS:SaoLourencoMember
867	SummaryOfIntangibleAssetsLineItems [Line Items]	LineItems			SBS:SummaryOfIntangibleAssetsLineItems
868	Current liabilities	Concept (Monetary)	As Of	Credit	SBS:PublicPrivatePartnershipCurrent
869	Noncurrent liabilities	Concept (Monetary)	As Of	Credit	SBS:PublicPrivatePartnershipNoncurrent
870	Liabilities	Concept (Monetary)	As Of	Credit	SBS:PublicPrivatePartnershipLiabilities
871	00000103 - Disclosure - 15. Intangible assets (Details Narrative)	Network	*	*	http://sabesp.com.br/role/IntangibleAssetsDetailsNarrative
872	Implied Table	Table	*	*	implied:Table
873	Intangible Assets	Abstract			SBS:IntangibleAssetsDetailsNarrativeAbstract
874	Indemnities receivable, noncurrent	Concept (Monetary)	As Of	Debit	SBS:IndemnitiesReceivableNoncurrent
875	Number of municipalities	Concept (Text/String)	For Period		SBS:NumberOfMunicipalities
876	Program Contracts Commitments, Current	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentContractLiabilities
877	Program Contracts Commitments, Noncurrent	Concept (Monetary)	As Of	Credit	ifrs-full:NoncurrentContractLiabilities
878	Capitalized interest and inflation adjustment	Concept (Monetary)	For Period		ifrs-full:BorrowingCostsCapitalised
879	Construction margin	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossRecognisedOnExchangingConstructionServicesForIntangibleAsset2011
880	Expropriations	Concept (Monetary)	For Period	Debit	SBS:ExpropriationCosts
881	Intangible assets - PPP	Concept (Monetary)	As Of	Credit	SBS:PublicPrivatePartnershipIntangibleAssets
882	Intangible assets, physical evolution of contruction - PPP	Concept (Percent)	For Period		SBS:IntangibleAssetsPhysicalEvolutionOfContructionPpp
883	Intangible assets, discount rate for adjustment - PPP	Concept (Percent)	For Period		SBS:IntangibleAssetsPhysicalEvolutionOfContructionDiscountRate
884	Intangible assets work in progress	Concept (Monetary)	As Of	Debit	SBS:WorkInProgressIntangibleAssets
885	Intangible assets work in progress - S�o Paulo	Concept (Monetary)	As Of	Debit	SBS:IntangibleAssetsWorkInProgressSaoPaulo
886	Intangible assets work in progress - PPP S�O LOUREN�O	Concept (Monetary)	As Of	Debit	SBS:IntangibleAssetsWorkInProgressPppSaoLourenco
887	Intangible assets work in progress - Franca	Concept (Monetary)	As Of	Debit	SBS:IntangibleAssetsWorkInProgressSaoPauloFranca
888	Intangible assets work in progress, Itanha�m	Concept (Monetary)	As Of	Debit	SBS:IntangibleAssetsWorkInProgressItanhaem
889	Amortization average rate	Concept (Percent)	For Period		SBS:AmortizationAverageRate
890	Intangible assets related to PPP ALTO TIET�	Concept (Monetary)	As Of	Debit	SBS:IntangibleAssetRelatedToPPPAltoTiete
891	Estimated monetary restatement	Concept (Monetary)	For Period	Debit	SBS:EstimatedMonetaryRestatement
892	Monthly assigned funds from tariffs	Concept (Monetary)	For Period	Debit	SBS:MonthlyAssignedFundsFromTariffs
893	Adjustment to present value of agreement	Concept (Percent)	For Period		SBS:AdjustmentToPresentValueOfAgreement
894	Agreement percentage of revenue - S�o Paulo	Concept (Percent)	For Period		SBS:AgreementPercentageOfRevenue
895	Construction margin	Concept (Percent)	For Period		SBS:RevenueFromConstructionServiceGrossMargin
896	Funds from tariffs arising from services provided - PPP S�o Louren�o	Concept (Monetary)	For Period	Debit	SBS:FundsFromTariffsArisingFromServicesProvided
897	00000104 - Disclosure - 16. Property, plant and equipment (Details)	Network	*	*	http://sabesp.com.br/role/PropertyPlantAndEquipmentDetails
898	SummaryOfPropertyPlantAndEquipmentTable [Table]	Table	*	*	SBS:SummaryOfPropertyPlantAndEquipmentTable
899	Property, plant and equipment by operating lease status [Axis]	Axis			ifrs-full:ClassesOfPropertyPlantAndEquipmentAxis
900	Property, plant and equipment [member]	Member			ifrs-full:PropertyPlantAndEquipmentMember
901	Land	Member			ifrs-full:LandMember
902	Buildings	Member			ifrs-full:BuildingsMember
903	Equipment	Member			ifrs-full:OfficeEquipmentMember
904	Transportation	Member			SBS:TransportEquipmentMember
905	Furniture and fixtures	Member			ifrs-full:FixturesAndFittingsMember
906	Other	Member			ifrs-full:OtherPropertyPlantAndEquipmentMember
907	Borrowings by name [axis]	Axis			ifrs-full:BorrowingsByNameAxis
908	Borrowings by name [member]	Member			ifrs-full:BorrowingsByNameMember
909	SummaryOfPropertyPlantAndEquipmentLineItems [Line Items]	LineItems			SBS:SummaryOfPropertyPlantAndEquipmentLineItems
910	Cost	Concept (Monetary)	As Of	Debit	ifrs-full:PropertyPlantAndEquipmentCarryingAmountAtCostOfRevaluedAssets
911	Accumulated amortization	Concept (Monetary)	As Of	Credit	SBS:PropertyPlantAndEquipmentAccumulatedAmortization
912	Net	Concept (Monetary)	As Of	Debit	ifrs-full:PropertyPlantAndEquipment
913	00000105 - Disclosure - 16. Property, plant and equipment (Details 1)	Network	*	*	http://sabesp.com.br/role/PropertyPlantAndEquipmentDetails1
914	SummaryOfPropertyPlantAndEquipmentTable [Table]	Table	*	*	SBS:SummaryOfPropertyPlantAndEquipmentTable
915	Property, plant and equipment by operating lease status [Axis]	Axis			ifrs-full:ClassesOfPropertyPlantAndEquipmentAxis
916	Property, plant and equipment [member]	Member			ifrs-full:PropertyPlantAndEquipmentMember
917	Land	Member			ifrs-full:LandMember
918	Buildings	Member			ifrs-full:BuildingsMember
919	Equipment	Member			ifrs-full:OfficeEquipmentMember
920	Transportation	Member			SBS:TransportEquipmentMember
921	Furniture and fixtures	Member			ifrs-full:FixturesAndFittingsMember
922	Other	Member			ifrs-full:OtherPropertyPlantAndEquipmentMember
923	SummaryOfPropertyPlantAndEquipmentLineItems [Line Items]	LineItems			SBS:SummaryOfPropertyPlantAndEquipmentLineItems
924	Property, plant, and equipment, beginning	Concept (Monetary)	As Of	Debit	ifrs-full:PropertyPlantAndEquipment
925	Additions	Concept (Monetary)	For Period	Debit	ifrs-full:AdditionsOtherThanThroughBusinessCombinationsPropertyPlantAndEquipment
926	Transfers	Concept (Monetary)	For Period	Debit	ifrs-full:IncreaseDecreaseThroughTransfersPropertyPlantAndEquipment
927	Write-offs and disposals	Concept (Monetary)	For Period		ifrs-full:WritedownsReversalsOfPropertyPlantAndEquipment
928	Depreciation	Concept (Monetary)	For Period		ifrs-full:DepreciationPropertyPlantAndEquipment
929	Property, plant, and equipment, ending	Concept (Monetary)	As Of	Debit	ifrs-full:PropertyPlantAndEquipment
930	00000106 - Disclosure - 16. Property, plant and equipment (Details Narrative)	Network	*	*	http://sabesp.com.br/role/PropertyPlantAndEquipmentDetailsNarrative
931	Implied Table	Table	*	*	implied:Table
932	Property Plant And Equipment	Abstract			SBS:PropertyPlantAndEquipmentDetailsNarrativeAbstract
933	Depreciation average rate	Concept (Text/String)	For Period		ifrs-full:UsefulLivesOrDepreciationRatesPropertyPlantAndEquipment
934	00000111 - Disclosure - 17. Borrowings and financing (Details 4)	Network	*	*	http://sabesp.com.br/role/BorrowingsAndFinancingDetails4
935	SummaryOfBorrowingsAndFinancingTable [Table]	Table	*	*	SBS:SummaryOfBorrowingsAndFinancingTable
936	Borrowings by name [axis]	Axis			ifrs-full:BorrowingsByNameAxis
937	Borrowings by name [member]	Member			ifrs-full:BorrowingsByNameMember
938	17th issue - series 1	Member			SBS:SeventeenthIssueSeries1Member
939	17th issue - series 2	Member			SBS:SeventeenthIssueSeries2Member
940	20th issue	Member			SBS:TwentiethIssueMember
941	10th issue	Member			SBS:TenthIssueMember
942	12th issue	Member			SBS:TwelfthIssueMember
943	14th issue	Member			SBS:FourteenthIssueMember
944	18th issue	Member			SBS:EighteenthIssueMember
945	SummaryOfBorrowingsAndFinancingLineItems [Line Items]	LineItems			SBS:SummaryOfBorrowingsAndFinancingLineItems
946	Amount	Concept (Monetary)	For Period	Debit	ifrs-full:AmortisationExpense
947	Maturity	Concept (Text/String)	For Period		ifrs-full:BorrowingsMaturity
948	Interest rates	Concept (Text/String)	For Period		ifrs-full:BorrowingsInterestRateBasis
949	00000112 - Disclosure - 17. Borrowings and financing (Details 5)	Network	*	*	http://sabesp.com.br/role/BorrowingsAndFinancingDetails5
950	SummaryOfBorrowingsAndFinancingTable [Table]	Table	*	*	SBS:SummaryOfBorrowingsAndFinancingTable
951	Borrowings by name [axis]	Axis			ifrs-full:BorrowingsByNameAxis
952	Borrowings by name [member]	Member			ifrs-full:BorrowingsByNameMember
953	22nd issue series 1	Member			SBS:TwentySecondIssueDebenturesSeries1Member
954	22nd issue series 2	Member			SBS:TwentySecondIssueDebenturesSeries2Member
955	22nd issue series 3	Member			SBS:TwentySecondIssueDebenturesSeries3Member
956	SummaryOfBorrowingsAndFinancingLineItems [Line Items]	LineItems			SBS:SummaryOfBorrowingsAndFinancingLineItems
957	Amount	Concept (Monetary)	For Period	Debit	ifrs-full:ProceedsFromCurrentBorrowings
958	Maturity	Concept (Text/String)	For Period		ifrs-full:BorrowingsMaturity
959	Remuneration	Concept (Text/String)	For Period		ifrs-full:BorrowingsInterestRateBasis
960	00000113 - Disclosure - 17. Borrowings and financing (Details 6)	Network	*	*	http://sabesp.com.br/role/BorrowingsAndFinancingDetails6
961	SummaryOfBorrowingsAndFinancingTable [Table]	Table	*	*	SBS:SummaryOfBorrowingsAndFinancingTable
962	Categories of related parties [axis]	Axis			ifrs-full:CategoriesOfRelatedPartiesAxis
963	Entity's total for related parties [member]	Member			ifrs-full:EntitysTotalForRelatedPartiesMember
964	Brazilian Federal Savings Bank	Member			SBS:BrazilianFederalSavingsBankMember
965	Brazilian Development Bank - BNDES BAIXADA SANTISTA	Member			SBS:BrazilianDevelopmentBankMember
966	Japan International Cooperation Agency - JICA	Member			SBS:JapanInternationalCooperationAgencyMember
967	Other	Member			SBS:OtherBankMember
968	SummaryOfBorrowingsAndFinancingLineItems [Line Items]	LineItems			SBS:SummaryOfBorrowingsAndFinancingLineItems
969	Borrowings and financing - Credit Limited	Concept (Monetary)	As Of	Credit	SBS:BorrowingsAndFinancingCreditLimited
970	00000115 - Disclosure - 18. Taxes recoverable/payable (Details)	Network	*	*	http://sabesp.com.br/role/TaxesRecoverablepayableDetails
971	SummaryOfTaxesRecoverablePayableTable [Table]	Table	*	*	SBS:SummaryOfTaxesRecoverablePayableTable
972	Temporary Difference Unused Tax Losses And Unused Tax Credits [Axis]	Axis			ifrs-full:TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis
973	Temporary difference, unused tax losses and unused tax credits [member]	Member			ifrs-full:TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsMember
974	Income tax and social contribution	Member			SBS:IncomeTaxAndSocialContributionMember
975	Withholding income tax on financial investments For - IRRF	Member			SBS:WithholdingIncomeTaxMember
976	Other federal taxes	Member			SBS:OtherFederalTaxesMember
977	SummaryOfTaxesRecoverablePayableLineItems [Line Items]	LineItems			SBS:SummaryOfTaxesRecoverablePayableLineItems
978	Current tax assets	Concept (Monetary)	As Of	Debit	ifrs-full:CurrentTaxAssets
979	00000116 - Disclosure - 18. Taxes recoverable/payable (Details 1)	Network	*	*	http://sabesp.com.br/role/TaxesRecoverablepayableDetails1
980	SummaryOfTaxesRecoverablePayableTable [Table]	Table	*	*	SBS:SummaryOfTaxesRecoverablePayableTable
981	Temporary Difference Unused Tax Losses And Unused Tax Credits [Axis]	Axis			ifrs-full:TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsAxis
982	Temporary difference, unused tax losses and unused tax credits [member]	Member			ifrs-full:TemporaryDifferenceUnusedTaxLossesAndUnusedTaxCreditsMember
983	Cofins and Pasep	Member			SBS:COFINSAndPasepMember
984	INSS (Social Security contribution)	Member			SBS:SocialSecurityContributionMember
985	IRRF (Withholding income tax on financial investments)	Member			SBS:IRRFWithholdingIncomeTaxOnFinancialInvestmentsMember
986	Other	Member			SBS:OtherTaxPayableMember
987	SummaryOfTaxesRecoverablePayableLineItems [Line Items]	LineItems			SBS:SummaryOfTaxesRecoverablePayableLineItems
988	Current tax liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:PayablesOnSocialSecurityAndTaxesOtherThanIncomeTax
989	00000120 - Disclosure - 19. Deferred taxes and contributions (Details 3)	Network	*	*	http://sabesp.com.br/role/DeferredTaxesAndContributionsDetails3
990	Implied Table	Table	*	*	implied:Table
991	Deferred Taxes And Contributions	Abstract			SBS:DeferredTaxesAndContributionsDetails3Abstract
992	Deferred tax assets (liabilities) net, beginning	Concept (Monetary)	As Of	Credit	ifrs-full:DeferredTaxLiabilityAsset
993	Net change in the year - corresponding entry to the income statement	Concept (Monetary)	For Period		ifrs-full:DeferredTaxExpenseIncomeRecognisedInProfitOrLoss
994	Net change in the year - corresponding entry to valuation adjustments to equity (Note 21 (b))	Concept (Monetary)	For Period	Credit	SBS:DeferredTaxesCorrespondingEntryToValuationAdjustmentsToEquity
995	Total net change	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseInDeferredTaxLiabilityAsset
996	Deferred tax assets (liabilities) net, ending	Concept (Monetary)	As Of	Credit	ifrs-full:DeferredTaxLiabilityAsset
997	00000121 - Disclosure - 19. Deferred taxes and contributions (Details 4)	Network	*	*	http://sabesp.com.br/role/DeferredTaxesAndContributionsDetails4
998	Implied Table	Table	*	*	implied:Table
999	Deferred Taxes And Contributions	Abstract			SBS:DeferredTaxesAndContributionsDetails4Abstract
1000	Profit before income taxes	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossBeforeTax
1001	Statutory rate	Concept (Percent)	For Period		ifrs-full:ApplicableTaxRate
1002	Estimated expense at statutory rate	Concept (Monetary)	For Period	Debit	ifrs-full:TaxExpenseIncomeAtApplicableTaxRate
1003	Tax benefit of interest on equity	Concept (Monetary)	For Period	Credit	ifrs-full:TaxBenefitArisingFromPreviouslyUnrecognisedTaxLossTaxCreditOrTemporaryDifferenceOfPriorPeriodUsedToReduceCurrentTaxExpense
1004	Permanent differences: Provision - Law 4,819/58	Concept (Monetary)	For Period	Debit	SBS:PermanentDifferencesProvisionLaw
1005	Permanent differences: Donations	Concept (Monetary)	For Period	Debit	SBS:PermanentDifferencesDonations
1006	Other differences	Concept (Monetary)	For Period	Debit	SBS:OtherTaxDifferences
1007	Income tax and social contribution	Concept (Monetary)	For Period	Debit	SBS:IncomeTaxAndSocialContribution
1008	Current income tax and social contribution	Concept (Monetary)	For Period	Debit	ifrs-full:IncomeTaxExpenseContinuingOperations
1009	Deferred income tax and social contribution	Concept (Monetary)	For Period	Debit	ifrs-full:DeferredTaxExpenseIncome
1010	Effective rate	Concept (Percent)	For Period		ifrs-full:AverageEffectiveTaxRate
1011	00000122 - Disclosure - 20. Provisions (Details)	Network	*	*	http://sabesp.com.br/role/ProvisionsDetails
1012	SummaryOfProvisionsTable [Table]	Table	*	*	SBS:SummaryOfProvisionsTable
1013	Classes of other provisions [Axis]	Axis			ifrs-full:ClassesOfProvisionsAxis
1014	Other provisions [member]	Member			ifrs-full:OtherProvisionsMember
1015	Customer claims	Member			SBS:CustomerClaimsMember
1016	Supplier claims	Member			SBS:SupplierClaimsMember
1017	Other civil claims	Member			SBS:OtherCivilClaimsMember
1018	Tax claims	Member			SBS:TaxClaimsMember
1019	Labor claims	Member			SBS:LaborClaimsMember
1020	Environmental claims	Member			SBS:EnvironmentalClaimsMember
1021	Current	Member			SBS:CurrentProvisionsMember
1022	Noncurrent	Member			SBS:NoncurrentProvisionsMember
1023	SummaryOfProvisionsLineItems [Line Items]	LineItems			SBS:SummaryOfProvisionsLineItems
1024	Provisions	Concept (Monetary)	As Of	Credit	SBS:ProvisionsGross
1025	Escrow deposits	Concept (Monetary)	As Of	Credit	ifrs-full:OtherProvisions
1026	Total	Concept (Monetary)	As Of	Credit	SBS:ProvisionsNet
1027	Current	Concept (Monetary)	As Of	Credit	ifrs-full:CurrentProvisions
1028	Noncurrent	Concept (Monetary)	As Of	Credit	ifrs-full:NoncurrentProvisions
1029	00000123 - Disclosure - 20. Provisions (Details 1)	Network	*	*	http://sabesp.com.br/role/ProvisionsDetails1
1030	SummaryOfProvisionsTable [Table]	Table	*	*	SBS:SummaryOfProvisionsTable
1031	Classes of other provisions [Axis]	Axis			ifrs-full:ClassesOfProvisionsAxis
1032	Other provisions [member]	Member			ifrs-full:OtherProvisionsMember
1033	Customer claims	Member			SBS:CustomerClaimsMember
1034	Supplier claims	Member			SBS:SupplierClaimsMember
1035	Other civil claims	Member			SBS:OtherCivilClaimsMember
1036	Tax claims	Member			SBS:TaxClaimsMember
1037	Labor claims	Member			SBS:LaborClaimsMember
1038	Environmental claims	Member			SBS:EnvironmentalClaimsMember
1039	Subtotal	Member			SBS:SubtotalClaimsMember
1040	Escrow deposits	Member			SBS:EscrowDepositsMember
1041	SummaryOfProvisionsLineItems [Line Items]	LineItems			SBS:SummaryOfProvisionsLineItems
1042	Provisions, beginning	Concept (Monetary)	As Of	Credit	ifrs-full:Provisions
1043	Additional provisions	Concept (Monetary)	For Period	Credit	ifrs-full:AdditionalProvisionsOtherProvisions
1044	Interest and inflation adjustment	Concept (Monetary)	For Period	Credit	ifrs-full:IncreaseDecreaseThroughTimeValueOfMoneyAdjustmentOtherProvisions
1045	Use of the accrual	Concept (Monetary)	For Period	Debit	ifrs-full:ProvisionUsedOtherProvisions
1046	Amounts not used (reversal)	Concept (Monetary)	For Period	Debit	ifrs-full:UnusedProvisionReversedOtherProvisions
1047	Provisions, ending	Concept (Monetary)	As Of	Credit	ifrs-full:Provisions
1048	00000124 - Disclosure - 20. Provisions (Details 2)	Network	*	*	http://sabesp.com.br/role/ProvisionsDetails2
1049	SummaryOfProvisionsTable [Table]	Table	*	*	SBS:SummaryOfProvisionsTable
1050	Classes of other provisions [Axis]	Axis			ifrs-full:ClassesOfProvisionsAxis
1051	Other provisions [member]	Member			ifrs-full:OtherProvisionsMember
1052	Customer claims	Member			SBS:CustomerClaimsMember
1053	Supplier claims	Member			SBS:SupplierClaimsMember
1054	Other civil claims	Member			SBS:OtherCivilClaimsMember
1055	Tax claims	Member			SBS:TaxClaimsMember
1056	Labor claims	Member			SBS:LaborClaimsMember
1057	Environmental claims	Member			SBS:EnvironmentalClaimsMember
1058	SummaryOfProvisionsLineItems [Line Items]	LineItems			SBS:SummaryOfProvisionsLineItems
1059	Significant contingent liabilities	Concept (Monetary)	As Of	Credit	ifrs-full:ContingentLiabilitiesIncurredInRelationToInterestsInAssociates
1060	00000125 - Disclosure - 20. Provisions (Details Narrative)	Network	*	*	http://sabesp.com.br/role/ProvisionsDetailsNarrative
1061	Implied Table	Table	*	*	implied:Table
1062	Provisions	Abstract			SBS:ProvisionsDetailsNarrativeAbstract
1063	Lawsuits filed by commercial customers	Concept (Text/String)	For Period		SBS:LawsuitsFiledByCommercialCustomers
1064	Lawsuits which customers claim a reduction in the sewage tariff	Concept (Text/String)	For Period		SBS:LawsuitsWhichCustomersClaimReductionInSewageTariff
1065	Lawsuits which customers plead reduction in tariff	Concept (Text/String)	For Period		SBS:LawsuitsWhichCustomersPleadReductionInTariff
1066	Tax claims related to income tax and social contribution	Concept (Monetary)	As Of	Credit	SBS:TaxClaimsRelatedToIncomeTaxAndSocialContribution
1067	Tax deficiency notice related to sewage services	Concept (Monetary)	For Period	Debit	SBS:TaxDeficiencyNoticeRelatedToSewageServices
1068	Offset requests for the extinction of IRPJ/CSLL payable	Concept (Monetary)	For Period	Debit	SBS:OffsetRequestsForExtinctionOfIPRJCSLLPayable
1069	Request for an authorization to offset taxes	Concept (Monetary)	For Period	Debit	SBS:RequestForAuthorizationToOffsetTaxes
1070	Lawsuits related to taxes and fines - accrued	Concept (Monetary)	As Of	Credit	SBS:LawsuitsRelatedToTaxesAndFinesAccrued
1071	Lawsuits related to taxes and fines - contingent liabilities	Concept (Monetary)	As Of	Credit	SBS:LawsuitsRelatedToTaxesAndFinesContingentLiabilities
1072	Intangible assets related to the municipalities	Concept (Monetary)	As Of	Debit	SBS:IntangibleAssetsRelatedToMunicipalities
1073	Indemnities receivable	Concept (Monetary)	As Of	Debit	SBS:IndemnitiesReceivable
1074	Increase in lawsuits deemed as contingent liabilities	Concept (Monetary)	As Of	Debit	SBS:IncreaseInLawsuitsDeemedAsContingentLiabilities
1075	Legal and administrative agreements	Concept (Monetary)	As Of	Credit	SBS:LegalAndAdministrativeAgreements
1076	Legal and administrative agreements related to construction	Concept (Monetary)	As Of	Credit	SBS:LegalAndAdministrativeAgreementsRelatedToConstruction
1077	Legal and administrative agreements related to environmental indemnifications	Concept (Monetary)	As Of	Credit	SBS:LegalAndAdministrativeAgreementsRelatedToEnvironmentalIndemnifications
1078	Environmental indemnifications	Concept (Monetary)	As Of	Credit	SBS:EnvironmentalIndemnifications
1079	Guarantee insurance for escrow deposit	Concept (Monetary)	As Of	Debit	SBS:GuaranteeInsuranceForEscrowDeposit
1080	Renewed guarantee insurance	Concept (Monetary)	As Of	Debit	SBS:GuaranteeInsuranceForEscrowDepositRenewed
1081	00000126 - Disclosure - 21. Employees benefits (Details)	Network	*	*	http://sabesp.com.br/role/EmployeesBenefitsDetails
1082	SummaryOfEmployeeBenefitsTable [Table]	Table	*	*	SBS:SummaryOfEmployeeBenefitsTable
1083	Defined benefit plans [axis]	Axis			ifrs-full:DefinedBenefitPlansAxis
1084	Defined benefit plans [member]	Member			ifrs-full:DefinedBenefitPlansMember
1085	Funded plan	Member			SBS:FundedPlanMember
1086	Unfunded plan	Member			SBS:UnfundedPlanMember
1087	SummaryOfEmployeeBenefitsLineItems [Line Items]	LineItems			SBS:SummaryOfEmployeeBenefitsLineItems
1088	Present value of defined benefit obligations	Concept (Monetary)	As Of	Credit	ifrs-full:DefinedBenefitObligationAtPresentValue
1089	Fair value of the plan's assets	Concept (Monetary)	As Of	Debit	ifrs-full:PlanAssetsAtFairValue
1090	Net liabilities recognized for defined benefit obligations	Concept (Monetary)	As Of	Debit	ifrs-full:SurplusDeficitInPlan
1091	Liability as per statement of financial position - pension obligations	Concept (Monetary)	As Of	Credit	SBS:LiabilityAsPerStatementOfFinancialPositionPensionObligations
1092	00000127 - Disclosure - 21. Employees benefits (Details 1)	Network	*	*	http://sabesp.com.br/role/EmployeesBenefitsDetails1
1093	SummaryOfEmployeeBenefitsTable [Table]	Table	*	*	SBS:SummaryOfEmployeeBenefitsTable
1094	Defined benefit plans [axis]	Axis			ifrs-full:DefinedBenefitPlansAxis
1095	Defined benefit plans [member]	Member			ifrs-full:DefinedBenefitPlansMember
1096	Funded plan - G1	Member			SBS:FundedPlanMember
1097	Unfunded plan	Member			SBS:UnfundedPlansMember
1098	SummaryOfEmployeeBenefitsLineItems [Line Items]	LineItems			SBS:SummaryOfEmployeeBenefitsLineItems
1099	Actuarial gains/(losses) on obligations	Concept (Monetary)	For Period	Debit	ifrs-full:GainsLossesArisingFromSettlementsNetDefinedBenefitLiabilityAsset
1100	Gains/(losses) on financial assets	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnFinancialAssetsAtFairValueThroughProfitOrLoss
1101	Total gains/(losses)	Concept (Monetary)	For Period	Debit	ifrs-full:GainLossOnRemeasurementOfNetDefinedBenefitLiabilityAsset
1102	Deferred income tax and social contribution - G1 Plan	Concept (Monetary)	For Period	Credit	SBS:DeferredIncomeTaxAndSocialContributionPlan
1103	Valuation adjustments to equity	Concept (Monetary)	For Period	Credit	ifrs-full:OtherComprehensiveIncomeBeforeTaxGainsLossesOnRemeasurementsOfDefinedBenefitPlans
1104	00000128 - Disclosure - 21. Employees benefits (Details 2)	Network	*	*	http://sabesp.com.br/role/EmployeesBenefitsDetails2
1105	Implied Table	Table	*	*	implied:Table
1106	Employees Benefits	Abstract			SBS:EmployeesBenefitsDetails2Abstract
1107	Defined benefit obligation, beginning of the year	Concept (Monetary)	As Of	Credit	ifrs-full:DefinedBenefitObligationAtPresentValue
1108	Current service cost	Concept (Monetary)	For Period	Credit	ifrs-full:CurrentServiceCostNetDefinedBenefitLiabilityAsset
1109	Interest cost	Concept (Monetary)	For Period	Credit	ifrs-full:InterestExpenseIncomeNetDefinedBenefitLiabilityAsset
1110	Actuarial (gains)/losses recorded as other comprehensive income	Concept (Monetary)	For Period	Debit	SBS:ActuarialGainsLossesRecordedAsOtherComprehensiveIncome
1111	Benefits paid	Concept (Monetary)	For Period	Debit	ifrs-full:PaymentsFromPlanNetDefinedBenefitLiabilityAsset
1112	Defined benefit obligation, end of the year	Concept (Monetary)	As Of	Credit	ifrs-full:DefinedBenefitObligationAtPresentValue
1113	00000129 - Disclosure - 21. Employees benefits (Details 3)	Network	*	*	http://sabesp.com.br/role/EmployeesBenefitsDetails3
1114	Implied Table	Table	*	*	implied:Table
1115	Employees Benefits	Abstract			SBS:EmployeesBenefitsDetails3Abstract
1116	Fair value of the plan's assets, beginning of the year	Concept (Monetary)	As Of	Debit	ifrs-full:PlanAssetsAtFairValue
1117	Expected return on the plan assets	Concept (Monetary)	For Period	Debit	ifrs-full:ReturnOnPlanAssetsNetDefinedBenefitLiabilityAsset
1118	Expected Company's contributions	Concept (Monetary)	For Period	Credit	SBS:EstimateOfContributionsExpectedToBePaidToPlanByCompany
1119	Expected participants' contributions	Concept (Monetary)	For Period	Debit	ifrs-full:ContributionsToPlanByPlanParticipantsNetDefinedBenefitLiabilityAsset
1120	Benefits paid	Concept (Monetary)	For Period	Debit	SBS:PaymentFromPlanNetDefinedBenefitLiabilityAsset
1121	Actuarial gains/(losses) included in other comprehensive income (loss)	Concept (Monetary)	For Period	Credit	ifrs-full:GainsLossesOnFinancialAssetsAtFairValueThroughProfitOrLoss
1122	Fair value of the plan's assets, end of the year	Concept (Monetary)	As Of	Debit	ifrs-full:PlanAssetsAtFairValue
1123	(Deficit)/Surplus	Concept (Monetary)	As Of	Debit	ifrs-full:SurplusDeficitInPlan
1124	00000130 - Disclosure - 21. Employees benefits (Details 4)	Network	*	*	http://sabesp.com.br/role/EmployeesBenefitsDetails4
1125	Implied Table	Table	*	*	implied:Table
1126	Employees Benefits	Abstract			SBS:EmployeesBenefitsDetails4Abstract
1127	Current service expenses	Concept (Monetary)	For Period	Credit	SBS:CurrentServiceCostEmployeeBenefits
1128	Interest cost rate	Concept (Monetary)	For Period	Credit	SBS:InterestCostRateEmployeeBenefits
1129	Expected return on the plan assets	Concept (Monetary)	For Period	Debit	ifrs-full:ReturnOnPlanAssetsNetDefinedBenefitLiabilityAsset
1130	Total expenses	Concept (Monetary)	For Period	Debit	ifrs-full:ContributionsToPlanNetDefinedBenefitLiabilityAsset
1131	00000131 - Disclosure - 21. Employees benefits (Details 5)	Network	*	*	http://sabesp.com.br/role/EmployeesBenefitsDetails5
1132	Implied Table	Table	*	*	implied:Table
1133	Employees Benefits	Abstract			SBS:EmployeesBenefitsDetails5Abstract
1134	Service cost	Concept (Monetary)	For Period	Credit	SBS:EstimateOfContributionExpectedToBePaidToPlan
1135	Interest cost rates	Concept (Monetary)	For Period	Credit	ifrs-full:EstimateOfContributionsExpectedToBePaidToPlan
1136	Participants' contributions	Concept (Monetary)	For Period	Credit	SBS:EstimateOfContributionsExpectedToBePaidToPlanByParticipants
1137	Net profitability on financial assets	Concept (Monetary)	For Period	Credit	SBS:NetProfitabilityOnFinancialAssets
1138	Expense to be recognized by employer	Concept (Monetary)	For Period	Debit	SBS:ExpensesToBeRecognizedByEmployer
1139	00000132 - Disclosure - 21. Employees benefits (Details 6)	Network	*	*	http://sabesp.com.br/role/EmployeesBenefitsDetails6
1140	Implied Table	Table	*	*	implied:Table
1141	Employees Benefits	Abstract			SBS:EmployeesBenefitsDetails6Abstract
1142	Discount rate	Concept (Percent)	As Of		ifrs-full:ActuarialAssumptionOfDiscountRates
1143	Inflation rate	Concept (Percent)	As Of		ifrs-full:ActuarialAssumptionOfExpectedRatesOfInflation
1144	Expected rate of return on assets	Concept (Percent)	As Of		ifrs-full:OtherMaterialActuarialAssumptions
1145	Future salary increase	Concept (Percent)	As Of		ifrs-full:ActuarialAssumptionOfExpectedRatesOfSalaryIncreases
1146	Mortality table	Concept (Text/String)	For Period		SBS:ActuarialAssumptionOfMortalityRates2
1147	00000134 - Disclosure - 21. Employees benefits (Details 8)	Network	*	*	http://sabesp.com.br/role/EmployeesBenefitsDetails8
1148	SummaryOfEmployeeBenefitsTable [Table]	Table	*	*	SBS:SummaryOfEmployeeBenefitsTable
1149	Defined benefit plans [axis]	Axis			ifrs-full:DefinedBenefitPlansAxis
1150	Defined benefit plans [member]	Member			ifrs-full:DefinedBenefitPlansMember
1151	NTNBs	Member			SBS:NTNBMember
1152	NTNCs	Member			SBS:NTNCMember
1153	Government bonds in own portfolio	Member			SBS:GovernmentBondMember
1154	Fixed income fund quotas	Member			SBS:FixedIncomeFundQuotasMember
1155	Private credit investment fund quotas	Member			SBS:PrivateCreditInvestmentFundQuotasMember
1156	Debentures	Member			SBS:DebenturesMember
1157	Stocks investment fund quotas	Member			SBS:StockInvestmentFundQuotasMember
1158	Shares	Member			SBS:SharesMember
1159	Equity investment fund quotas	Member			SBS:EquityInvestmentFundQuotasMember
1160	Real estate investment fund quotas	Member			SBS:RealEstateInvestmentFundQuotasMember
1161	Multimarket investment fund quotas	Member			SBS:MultimarketInvestmentFundQuotasMember
1162	SummaryOfEmployeeBenefitsLineItems [Line Items]	LineItems			SBS:SummaryOfEmployeeBenefitsLineItems
1163	Fixed income	Concept (Monetary)	As Of	Debit	ifrs-full:InvestmentFundsAmountContributedToFairValueOfPlanAssets
1164	Equities	Concept (Monetary)	As Of	Debit	ifrs-full:EquityInstrumentsAmountContributedToFairValueOfPlanAssets
1165	Structured investments	Concept (Monetary)	As Of	Debit	ifrs-full:StructuredDebtAmountContributedToFairValueOfPlanAssets
1166	Other	Concept (Monetary)	As Of	Debit	ifrs-full:OtherAssetsAmountContributedToFairValueOfPlanAssets
1167	Fair value of plan's assets	Concept (Monetary)	As Of	Debit	ifrs-full:PlanAssetsAtFairValue
1168	00000135 - Disclosure - 21. Employees benefits (Details 9)	Network	*	*	http://sabesp.com.br/role/EmployeesBenefitsDetails9
1169	SummaryOfEmployeeBenefitsTable [Table]	Table	*	*	SBS:SummaryOfEmployeeBenefitsTable
1170	Defined benefit plans [axis]	Axis			ifrs-full:DefinedBenefitPlansAxis
1171	Defined benefit plans [member]	Member			ifrs-full:DefinedBenefitPlansMember
1172	Unfunded plan	Member			SBS:UnfundedPlansMember
1173	SummaryOfEmployeeBenefitsLineItems [Line Items]	LineItems			SBS:SummaryOfEmployeeBenefitsLineItems
1174	Defined benefit obligation, beginning of the year	Concept (Monetary)	As Of	Credit	ifrs-full:DefinedBenefitObligationAtPresentValue
1175	Current interest expense and service costs	Concept (Monetary)	For Period	Credit	ifrs-full:EstimateOfContributionsExpectedToBePaidToPlan
1176	Actuarial (gains)/losses recorded as other comprehensive income	Concept (Monetary)	For Period	Debit	ifrs-full:ActuarialGainsLossesArisingFromChangesInFinancialAssumptionsNetDefinedBenefitLiabilityAsset
1177	Benefits paid	Concept (Monetary)	For Period	Debit	ifrs-full:PaymentsFromPlanNetDefinedBenefitLiabilityAsset
1178	Defined benefit obligation, end of the year	Concept (Monetary)	As Of	Credit	ifrs-full:DefinedBenefitObligationAtPresentValue
1179	00000136 - Disclosure - 21. Employees benefits (Details 10)	Network	*	*	http://sabesp.com.br/role/EmployeesBenefitsDetails10
1180	SummaryOfEmployeeBenefitsTable [Table]	Table	*	*	SBS:SummaryOfEmployeeBenefitsTable
1181	Defined benefit plans [axis]	Axis			ifrs-full:DefinedBenefitPlansAxis
1182	Defined benefit plans [member]	Member			ifrs-full:DefinedBenefitPlansMember
1183	Unfunded plan	Member			SBS:UnfundedPlansMember
1184	Unfunded plan	Member			SBS:UnfundedPlanMember
1185	SummaryOfEmployeeBenefitsLineItems [Line Items]	LineItems			SBS:SummaryOfEmployeeBenefitsLineItems
1186	Current interest expense and service costs	Concept (Monetary)	For Period	Credit	ifrs-full:EstimateOfContributionsExpectedToBePaidToPlan
1187	Amount received from GESP (undisputed amount)	Concept (Monetary)	For Period	Debit	SBS:AmountReceivedFromGESP
1188	Expense to be recognize	Concept (Monetary)	For Period	Debit	ifrs-full:ContributionsToPlanNetDefinedBenefitLiabilityAsset
1189	Interest cost rate	Concept (Monetary)	For Period	Credit	ifrs-full:InterestExpenseIncomeNetDefinedBenefitLiabilityAsset
1190	Expense to be recognize	Concept (Monetary)	For Period	Debit	SBS:ExpenseToBeRecognizedByEmployer
1191	00000137 - Disclosure - 21. Employees benefits (Details 11)	Network	*	*	http://sabesp.com.br/role/EmployeesBenefitsDetails11
1192	SummaryOfEmployeeBenefitsTable [Table]	Table	*	*	SBS:SummaryOfEmployeeBenefitsTable
1193	Defined benefit plans [axis]	Axis			ifrs-full:DefinedBenefitPlansAxis
1194	Defined benefit plans [member]	Member			ifrs-full:DefinedBenefitPlansMember
1195	Unfunded plan	Member			SBS:UnfundedPlansMember
1196	SummaryOfEmployeeBenefitsLineItems [Line Items]	LineItems			SBS:SummaryOfEmployeeBenefitsLineItems
1197	Discount rate	Concept (Percent)	As Of		ifrs-full:ActuarialAssumptionOfDiscountRates
1198	Inflation rate	Concept (Percent)	As Of		ifrs-full:ActuarialAssumptionOfExpectedRatesOfInflation
1199	Future salary increase	Concept (Percent)	As Of		ifrs-full:ActuarialAssumptionOfExpectedRatesOfSalaryIncreases
1200	Mortality table	Concept (Text/String)	For Period		SBS:ActuarialAssumptionOfMortalityRates2
1201	00000140 - Disclosure - 22. Services payable (Details Narrative)	Network	*	*	http://sabesp.com.br/role/ServicesPayableDetailsNarrative
1202	Implied Table	Table	*	*	implied:Table
1203	Services Payable	Abstract			SBS:ServicesPayableDetailsNarrativeAbstract
1204	Services payable	Concept (Monetary)	As Of	Credit	SBS:ServicesPayable
1205	00000141 - Disclosure - 23. Knowledge retention program (Details)	Network	*	*	http://sabesp.com.br/role/KnowledgeRetentionProgramDetails
1206	SummaryOfKnowledgeRetentionProgramTable [Table]	Table	*	*	SBS:SummaryOfKnowledgeRetentionProgramTable
1207	Range [Axis]	Axis			srt:RangeAxis
1208	Range [Domain]	Member			srt:RangeMember
1209	More than 15 years	Member			SBS:MoreThanFifteenYearsMember
1210	11 - 15 years	Member			SBS:ElevenToFifteenYearsMember
1211	6 - 10 years	Member			SBS:SixToTenYearsMember
1212	0 - 5 years	Member			SBS:ZeroToFiveYearsMember
1213	SummaryOfKnowledgeRetentionProgramLineItems [Line Items]	LineItems			SBS:SummaryOfKnowledgeRetentionProgramLineItems
1214	Percent of the Guarantee Fund for Length of Service (FGTS)	Concept (Percent)	For Period		SBS:PercentOfGuaranteeFundForLengthOfService
1215	00000142 - Disclosure - 24. Equity (Details)	Network	*	*	http://sabesp.com.br/role/EquityDetails
1216	SummaryOfEquityTable [Table]	Table	*	*	SBS:SummaryOfEquityTable
1217	Classes of entity's own equity instruments [axis]	Axis			ifrs-full:ClassesOfEntitysOwnEquityInstrumentsAxis
1218	Entity's own equity instruments [member]	Member			ifrs-full:EntitysOwnEquityInstrumentsMember
1219	State Department of Finance	Member			SBS:StateDepartmentOfFinanceMember
1220	Companhia Brasileira de Liquidacao e Custodia	Member			SBS:CompanhiaBrasileiraDeLiquidacaoECustodiaMember
1221	The Bank of New York ADR Department	Member			SBS:BankOfNewYorkADRDepartmentMember
1222	Other	Member			SBS:OtherEntityEquitytMember
1223	SummaryOfEquityLineItems [Line Items]	LineItems			SBS:SummaryOfEquityLineItems
1224	Number of shares	Concept (Shares)	As Of		ifrs-full:NumberOfSharesIssued
1225	Percentage of shares	Concept (Shares)	For Period		SBS:PercentageOfSharesHeld
1226	00000143 - Disclosure - 24. Equity (Details 1)	Network	*	*	http://sabesp.com.br/role/EquityDetails1
1227	Implied Table	Table	*	*	implied:Table
1228	Equity	Abstract			SBS:EquityDetails1Abstract
1229	Profit for the year	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
1230	(-) Legal reserve - 5%	Concept (Monetary)	As Of	Credit	ifrs-full:StatutoryReserve
1231	Distribution of earnings	Concept (Monetary)	For Period	Credit	SBS:ProfitForTheYearNetOfLegalReserve
1232	Minimum mandatory dividend - 25% (R$0.9851, R$0.87539 and R$1.0240 as of December 31, 2018, 2017 and 2016 per share and per ADS)	Concept (Monetary)	For Period	Debit	SBS:MinimumMandatoryDividend
1233	00000144 - Disclosure - 24. Equity (Details 2)	Network	*	*	http://sabesp.com.br/role/EquityDetails2
1234	Implied Table	Table	*	*	implied:Table
1235	Equity	Abstract			SBS:EquityDetails2Abstract
1236	Profit for the year	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
1237	Legal reserve	Concept (Monetary)	As Of	Credit	ifrs-full:StatutoryReserve
1238	Minimum mandatory dividends	Concept (Monetary)	For Period	Debit	SBS:MinimumMandatoryDividend
1239	Additional proposed dividends	Concept (Monetary)	For Period	Debit	SBS:AdditionalProposedDividends
1240	Investment reserve recorded	Concept (Monetary)	For Period	Credit	SBS:InvestmentReserveRecorded
1241	00000145 - Disclosure - 24. Equity (Details 3)	Network	*	*	http://sabesp.com.br/role/EquityDetails3
1242	SummaryOfEquityTable [Table]	Table	*	*	SBS:SummaryOfEquityTable
1243	Defined benefit plans [axis]	Axis			ifrs-full:DefinedBenefitPlansAxis
1244	Defined benefit plans [member]	Member			ifrs-full:DefinedBenefitPlansMember
1245	Funded plan - G1	Member			SBS:FundedPlanMember
1246	Unfunded plan	Member			SBS:UnfundedPlansMember
1247	SummaryOfEquityLineItems [Line Items]	LineItems			SBS:SummaryOfEquityLineItems
1248	Other comprehensive loss, beginning	Concept (Monetary)	As Of	Credit	ifrs-full:AccumulatedOtherComprehensiveIncome
1249	Actuarial gains (losses)	Concept (Monetary)	For Period	Debit	ifrs-full:ActuarialGainsLossesArisingFromChangesInFinancialAssumptionsNetDefinedBenefitLiabilityAsset
1250	Other comprehensive loss, ending	Concept (Monetary)	As Of	Credit	ifrs-full:AccumulatedOtherComprehensiveIncome
1251	00000146 - Disclosure - 24. Equity (Details Narrative)	Network	*	*	http://sabesp.com.br/role/EquityDetailsNarrative
1252	Implied Table	Table	*	*	implied:Table
1253	Equity	Abstract			SBS:EquityDetailsNarrativeAbstract
1254	Authorized capital	Concept (Monetary)	For Period	Credit	SBS:AuthorizedCapital
1255	Minimum mandatory dividend per share and per ADS	Concept (Share)	For Period		SBS:MinimumMandatoryDividendPerShareAndPerADS
1256	Additional proposed dividends	Concept (Monetary)	For Period	Debit	SBS:AdditionalProposedDividends
1257	Withholding income tax recognized in current liabilities	Concept (Monetary)	As Of	Credit	SBS:DividendsWithholdingIncomeTaxRecognizedInCurrentLiabilities
1258	Interest on capital balance payable	Concept (Monetary)	As Of	Credit	ifrs-full:DividendPayables
1259	Interest on capital balance payable declared	Concept (Monetary)	As Of	Credit	SBS:DeclaredDividendPayables
1260	Interest on capital balance payable witheld income tax	Concept (Monetary)	As Of	Credit	SBS:DividendsWitheldIncomeTax
1261	Investment reserve	Concept (Monetary)	For Period	Credit	SBS:InvestmentReserve
1262	Subscribed and paid-in-capital	Concept (Shares)	For Period		SBS:SubscribedAndPaidincapital
1263	Surplus minimum mandatory	Concept (Monetary)	For Period	Debit	SBS:SurplusMinimumMandatory
1264	Dividends	Concept (Monetary)	For Period	Credit	ifrs-full:DividendsPaidClassifiedAsOperatingActivities
1265	Dividend per common share	Concept (Share)	For Period		ifrs-full:DividendsPaidOrdinarySharesPerShare
1266	00000147 - Disclosure - 25. Earnings per share (Details)	Network	*	*	http://sabesp.com.br/role/EarningsPerShareDetails
1267	Implied Table	Table	*	*	implied:Table
1268	Earnings Per Share	Abstract			SBS:EarningsPerShareDetailsAbstract
1269	Equity attributable to Company's owners	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLoss
1270	Number of shares	Concept (Shares)	As Of		ifrs-full:NumberOfSharesIssued
1271	Basic and diluted earnings per share (reais per share)	Concept (Share)	For Period		ifrs-full:BasicAndDilutedEarningsLossPerShare
1272	00000148 - Disclosure - 26. Operating segment information (Details)	Network	*	*	http://sabesp.com.br/role/OperatingSegmentInformationDetails
1273	SummaryOfOperatingSegmentInformationTable [Table]	Table	*	*	SBS:SummaryOfOperatingSegmentInformationTable
1274	Segment consolidation items [axis]	Axis			ifrs-full:SegmentConsolidationItemsAxis
1275	Entity's total for segment consolidation items [member]	Member			ifrs-full:EntitysTotalForSegmentConsolidationItemsMember
1276	Sanitation	Member			SBS:SanitationMember
1277	Reconciliation to the financial statements	Member			SBS:ReconciliationMember
1278	SummaryOfOperatingSegmentInformationLineItems [Line Items]	LineItems			SBS:SummaryOfOperatingSegmentInformationLineItems
1279	Gross operating revenue	Concept (Monetary)	For Period	Credit	ifrs-full:RevenueAndOperatingIncome
1280	Gross sales deductions	Concept (Monetary)	For Period	Debit	SBS:GrossSalesDeductions
1281	Net operating revenue	Concept (Monetary)	For Period	Credit	ifrs-full:Revenue
1282	Costs, selling and administrative expenses	Concept (Monetary)	For Period	Debit	SBS:CostsSellingAndAdministrativeExpenses
1283	Income from operations before other operating expenses, net and equity accounting	Concept (Monetary)	For Period	Credit	SBS:IncomeFromOperationsBeforeOtherOperatingExpensesNetAndEquityAccounting
1284	Other operating income / (expenses), net	Concept (Monetary)	For Period	Credit	ifrs-full:OtherOperatingIncomeExpense
1285	Equity accounting	Concept (Monetary)	For Period	Credit	SBS:EquityInResultsOfInvestmentsInAffiliaties
1286	Financial result, net	Concept (Monetary)	For Period	Credit	SBS:FinanceIncomeExpenseNet
1287	Income from operations before taxes	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossBeforeTax
1288	Depreciation and amortization	Concept (Monetary)	For Period	Debit	ifrs-full:DepreciationAndAmortisationExpense
1289	00000149 - Disclosure - 26. Operating segment information (Details 1)	Network	*	*	http://sabesp.com.br/role/OperatingSegmentInformationDetails1
1290	Implied Table	Table	*	*	implied:Table
1291	Operating Segment Information	Abstract			SBS:OperatingSegmentInformationDetails1Abstract
1292	Gross revenue from construction recognized under IFRIC 12	Concept (Monetary)	For Period	Credit	ifrs-full:RevenueRecognisedOnExchangingConstructionServicesForIntangibleAsset
1293	Construction costs recognized under IFRIC 12	Concept (Monetary)	For Period	Debit	SBS:ConstructionCostIncurred
1294	Construction margin	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossRecognisedOnExchangingConstructionServicesForIntangibleAsset2011
1295	00000150 - Disclosure - 27. Insurance (Details)	Network	*	*	http://sabesp.com.br/role/InsuranceDetails
1296	SummaryOfInsuranceTable [Table]	Table	*	*	SBS:SummaryOfInsuranceTable
1297	Types of insurance contracts [axis]	Axis			ifrs-full:TypesOfInsuranceContractsAxis
1298	Types of insurance contracts [member]	Member			ifrs-full:InsuranceContractsMember
1299	Specified risks - fire	Member			SBS:SpecifiedRiskMember
1300	Engineering risk	Member			SBS:EngineeringRiskMember
1301	Guarantee insurance for escrow deposit	Member			SBS:GuaranteeInsuranceEscrowDepositMember
1302	Traditional guarantee insurance	Member			SBS:TraditionalGuaranteeInsuranceMember
1303	Civil liability- DO (Directors and Officers)	Member			SBS:CivilLiabilityDirectorsAndOfficersMember
1304	Civil liability- works	Member			SBS:CivilLiabilityWorksMember
1305	Domestic and international transportation	Member			SBS:DomesticAndInternationalTransportationMember
1306	Civil liability - operations	Member			SBS:CivilLiabilityOperationsMember
1307	Other	Member			SBS:OtherInsuranceCoverageMember
1308	SummaryOfInsuranceLineItems [Line Items]	LineItems			SBS:SummaryOfInsuranceLineItems
1309	Coverage	Concept (Monetary)	As Of	Debit	SBS:InsutanceCoverage
1310	00000152 - Disclosure - 28. Operating revenue (Details 1)	Network	*	*	http://sabesp.com.br/role/OperatingRevenueDetails1
1311	Implied Table	Table	*	*	implied:Table
1312	Operating Revenue	Abstract			SBS:OperatingRevenueDetails1Abstract
1313	Sanitation services	Concept (Monetary)	For Period	Credit	SBS:SanitationServicesRevenue
1314	Construction revenue	Concept (Monetary)	For Period	Credit	SBS:RevenueFromConstruction
1315	Sales Tax	Concept (Monetary)	For Period	Debit	SBS:SalesTaxOnRevenue
1316	Regulation, Control and Oversight Fee (TRCF) (ii)	Concept (Monetary)	For Period	Debit	SBS:RegulationControlAndOversightFee
1317	Net operating revenue	Concept (Monetary)	For Period	Credit	ifrs-full:Revenue
1318	00000155 - Disclosure - 31. Other operating income (expenses), net (Details)	Network	*	*	http://sabesp.com.br/role/OtherOperatingIncomeExpensesNetDetails
1319	Implied Table	Table	*	*	implied:Table
1320	Other Operating Income Expenses Net	Abstract			SBS:OtherOperatingIncomeExpensesNetDetailsAbstract
1321	Other operating income, net	Concept (Monetary)	For Period	Credit	ifrs-full:MiscellaneousOtherOperatingIncome
1322	Other operating expenses	Concept (Monetary)	For Period	Debit	ifrs-full:MiscellaneousOtherOperatingExpense
1323	Other operating income (expenses), net	Concept (Monetary)	For Period	Credit	ifrs-full:OtherOperatingIncomeExpense
1324	00000156 - Disclosure - 32. Commitments (Details)	Network	*	*	http://sabesp.com.br/role/CommitmentsDetails
1325	SummaryOfCommitmentsTable [Table]	Table	*	*	SBS:SummaryOfCommitmentsTable
1326	Range [axis]	Axis			ifrs-full:RangeAxis
1327	Ranges [member]	Member			ifrs-full:RangesMember
1328	1 year	Member			SBS:OneYearMember
1329	1-3 years	Member			SBS:OneToThreeYearsMember
1330	3-5 years	Member			SBS:ThreeToFiveYearsMember
1331	More than 5 years	Member			SBS:MoreThanFiveYearsMember
1332	SummaryOfCommitmentsLineItems [Line Items]	LineItems			SBS:SummaryOfCommitmentsLineItems
1333	Contractual obligations, Expenses	Concept (Monetary)	As Of	Credit	SBS:ContractLiabilitiesExpenses
1334	Contractual obligations, Investments	Concept (Monetary)	As Of	Credit	SBS:ContractLiabilitiesInvestments
1335	Contractual obligations, Total	Concept (Monetary)	As Of	Credit	ifrs-full:ContractLiabilities
1336	00000157 - Disclosure - 33. Supplemental cash flow information (Details)	Network	*	*	http://sabesp.com.br/role/SupplementalCashFlowInformationDetails
1337	Implied Table	Table	*	*	implied:Table
1338	Supplemental Cash Flow Information	Abstract			SBS:SupplementalCashFlowInformationDetailsAbstract
1339	Total additions of contract assets (Note 14)	Concept (Monetary)	For Period	Debit	SBS:AdditionsToContractAssets
1340	Total additions to intangible assets (Note 15 (b))	Concept (Monetary)	For Period	Debit	ifrs-full:AdditionsOtherThanThroughBusinessCombinationsIntangibleAssetsOtherThanGoodwill
1341	Items not affecting cash (see breakdown below)	Concept (Monetary)	For Period	Credit	SBS:ItemsNotAffectingCash
1342	Total additions to intangible assets as per statement of cash flows	Concept (Monetary)	For Period	Credit	ifrs-full:PurchaseOfIntangibleAssetsClassifiedAsInvestingActivities
1343	Investment and financing operations affecting intangible assets but not cash:	Abstract			SBS:InvestmentsAndFinancingOperationsAffectingIntangibleAssetsButNotCashAbstract
1344	Interest capitalized in the year	Concept (Monetary)	For Period		ifrs-full:BorrowingCostsCapitalised
1345	Contractors payable	Concept (Monetary)	For Period	Credit	SBS:ContractorsPayable
1346	Program contract commitments	Concept (Monetary)	For Period	Credit	SBS:ContractCommitments
1347	Public Private Partnership - Sao Lourenco PPP	Concept (Monetary)	For Period	Credit	SBS:PublicPrivatePartnershipSaoLourenco
1348	Leases	Concept (Monetary)	For Period	Credit	SBS:Leases
1349	Construction margin	Concept (Monetary)	For Period	Credit	ifrs-full:ProfitLossRecognisedOnExchangingConstructionServicesForIntangibleAsset2011
1350	Agreement signed with the municipality of Guarulhos (Note 9 (a))	Concept (Monetary)	For Period	Credit	SBS:AgreementSignedwithMunicipalityofGuarulhos
1351	Total	Concept (Monetary)	For Period	Credit	SBS:ItemsNotAffectingCash