Assessment of performance indicators for different sizes of water supply systems in Minas Gerais, Brazil.

Indicators are important tools to improve the efficiency of water supply systems. Considering that the performance could vary according to the systems' sizes, this research proposed financial, operational, and water quality indicators for water supply systems of municipalities with different populations in Minas Gerais, Brazil. The organisation and selection of the sample were based on available information in the National Sanitation Data System of 2014. We selected 363 municipalities of Minas Gerais and 56 predictors. Through multiple linear regression (MLR), we found that the commitment of revenues with expenditures and the ratio among revenues and expenses are the most relevant variables to describe the financial performance. Furthermore, water loss per connection and water-billing index were the most important to describe the operational performance. Finally, models related to water quality performance could not be established due to the low value of the coefficient of determination. We observed that supply systems have distinct variables to describe their financial and operational performance, according to their sizes. Small municipalities have a strong relationship with financial performance and expenses. Large counterparts have their performance related to the collection, which can be explained by the economy of scale. Considering the operational performance, we observed that larger municipalities have a strong relationship between their operational performance and water loss. These models are potential tools in the decision-making processes, which can be used to promote improvements in water supply systems.