This study proposes a method for the diagnosis of real water loss and for the actions which reduce this problem in water distribution systems. By adopting the parameters involved in the evaluation of real water loss, actions targeting combat and reduction of loss are prioritized, which allows for the optimization of the available resources. The topic of water loss reduction has recently been widely discussed, which is especially related to advances in information technology and to the availability of data within Brazilian water supply systems. The greater Sao Paulo area is one of the world's most populated areas, with 20 million inhabitants. The Water System Cantatereira of Sao Paulo is very important in this area, supplying water to 60% of the entire population. In this system, one of the most relevant distributors is the Casa Verde Sector, composed of 84.2 kilometers of water distribution networks, 11,002 connections, and 16,891 homes, all with a water flow of 201.9 l/s. With the employment of geophones, listening stems and leak noise correlation, non-visible leaks were detected in this important and complex system, when water flow and pressure were recorded. All data was analyzed and correlated with information in the Geographic Information System (GIS). This study presents the results yielded by analyzes carried out with the software Water Audit 4. This software can be applied to any water supply system and is provided at no cost by the American Water Works Association (AWWA). It was concluded that the Casa Verde Sector must develop a specific strategy for water loss reduction, based on the renovation of the facilities and on the method of storage used for pressure data. © 2013 WIT Press.171 2333WIT Transactions on Ecology and The Environment,International Journal of Sustainable Development and PlanningThornton, J., Sturm, R., Kunkel, G., (2008) Water Loss Control, pp. 345-350. , 2nd ed. EUA. McGraw-HillLiemberger, R., Marin, P., (2006) Water Supply and Sanitation Board Discussion Paper Series, p. 52. , Paper n. 08 The World Bank, Washington, DC(2010) In: XX Water Loss Conference, p. 1080. , American Water Works Association (AWWA), São Paulo, Annals(2009) SNIS /PMSS - Diagnostics of Water and Sewage Services, , Ministry of Cities. National secretary of environmental sanitation, BrazilLambert, A., Thornton, J., (2002) Evaluation of Real Losses, p. 132. , São Paulo Region. SABESPFantozzi, M., Some examples of European water loss targets, and the law of unintended Consequences (2010) Water Loss, p. 192. , São PauloMelato, D.S., (2010) Discussion of a Methodology For the Diagnostics of and Actions to Reduce Water Loss: Application In the Water Supply System of the São Paulo Great Area, , Thesis (Master's in Civil Engineering). University of São Paulo's "Escola Politécnica", São Paulo(2006) Signos-geographic Information System In Sanitation, , http://www.premiomariocovas.sp.gov.br/pesquisa2005/tic%20transacoes%20internas/tt_274.doc, Sabesp, Available at, Accessed on: March 22nd(2005) Management of Water Loss, p. 44. , http://www.cidades.gov.br/index.php?option=com_content&view=article&id=405:indicadores&catid=90&itemid=119, Sabesp. Companhia de saneamento básico do estado de São Paulo (Agency of basic sanitation of the State of São Paulo), Department of integrated planning "MPI", Accessed on: Aug 18th 2011Diniz, A.R., (2012) Evaluation of Physical Loss Control In Water Distribution Systems of the São Paulo Metropolitan Region, , Thesis (Master's In Civil Engineering, University of Campinas, Campinas(2011) Water Audit 4 - AWWA Water Loss Control Committee Water Audit Software Compiler V4.2.9, , http://www.awwa.org/resources-tools/waterknowledge/water-loss-control.aspx, American water Works association (AWWA), Available at