Conference Call 1Q13 Results May/2013 Economic-Financial Office and Investor Relations Office

Notice This presentation may contain forward-looking statements referring to SABESP’s business outlook. operating and financial results estimates. and growth prospects. These are only projections. and as such. they are exclusively based on SABESP’s management expectation in relation to the future of business and its continuous access to capital to finance the Company’s business plan. These forward-looking statements largely depend on changes in market conditions. governmental rules. industry performance and the Brazilian economy. amongst other factors. in addition to risks exhibited in disclosure documents filed by SABESP. Therefore. they are subject to changes without prior notice. 2

Total water and sewage billed volume, including wholesale (million m³) 2.0% 905.5 923.9 1.9% 2.1% 3

Financial Highligts (R$ million) 4

Costs and Expenses (R$ million) Costs and expenses in 1Q12-: R$ 1,334.8 Costs and expenses in 1Q13*: R$ 1,432.6 7.3% 13.7% *Not including construction costs (13.7%) 28.4% 4.7% (3.7%) 9.4% 45.5% (3.6%) 14.6% % Net Revenue in 1Q12 15.8% 1.6% 1.7% 10.3% 5.8% 6.5% 7.2% 1.5% 1.4% % Net Revenue in 1Q13 17.5% 2.5% 8.6% 5.5% 8.1% 7.4% 5

Net Income – Main variations 6

Tariff March 22, 2013 April 19, 2013 August 2013 ARSESP Published Resolution 406 and Resolution 407 April 19, 2013 ARSESP Publishes Resolution 413 August 2013 ARSESP Publishes the Final Maximum Average Tariff 406: Establishes mainly; (i) a preliminary initial maximum average tariff (Preliminary P0), that implies in a linear tariff increase of 2.3509%; (ii) authorization for the Company to pass on to the customers service bill the Regulation and Oversight Fee of 0.5%; (iii) an annual tariff adjustment formula, to be implemented during the second tariff cycle. 407: Authorizes Sabesp to pass on to customers service bill, municipal charges legally established and related to Program Contracts and Service Contracts, that must be considered in the Tariff Revision.   413: Suspends application on Resolution 407, postponing the Company’s right to pass on the municipal charges to customers service bill until a final maximum average tariff (Final P0) is defined. 7

www.sabesp.com.br IR Contacts Mario Azevedo de Arruda Sampaio Angela Beatriz Airoldi maasampaio@sabesp.com.br abairoldi@sabesp.com.br (55 11) 3388-8664 (55 11) 3388-8793