The regulatory model developed by ERSAR focuses on the structural regulation of the sector, on the regulation of the operators’ behaviour and in additional regulatory activities. These dimensions must be perfectly articulated, allowing ERSAR to build a coherent model.

The tariffs should ensure an adequate return of investment and services operational costs, as well as of environment and scarcity costs. The procedure of defining tariffs is different depending on the operator's management model. End-user expenses with water and waste services are defined for each municipality according to three different levels of use (60 m³, 120 m³ and 180 m³).

The fact that the water and waste services represent a natural monopoly of local or regional basis affects the competition in the sector and, because of this, the consumers can’t choose the operator that they prefer or the price/quality relationship that they see as more convenient.

Drinking water quality is an essential indicator for assessing the development of each country and the well-being of the population. Portugal has witnessed a very positive evolution in drinking water quality and in the number of mandatory analysis undertaken for water control purposes. The most recent national data points to a significant improvement of the drinking water control in the last decade.

The regulation of the quality of service aims to improve the efficacy and efficiency of the water and waste services. This regulation is done by assessing the performance of the various operators. This assessment follows a set of indicators, related to drinking water supply, urban wastewater management and urban waste management services, which allow ERSAR to regulate by benchmarking.