There are four relevant periods in the regulation of the water and waste sector in Portugal:
2000 – 2003:
IRAR was the regulation authority for water and waste services of a growing number of concessionaires. At the end of 2003, there were about 50 regulated operators.
2004 – 2009:
Besides regulating these 50 operators, IRAR assumed the role of national authority for drinking water quality. In this respect, IRAR had more 400 operators to regulate.
Since 2009:
ERSAR replaced IRAR and is now the regulation authority for the entire water and waste sector, with over 500 regulated operators, keeping its mission as national authority for drinking water quality.
In 2014 ERSAR became an independent body with more autonomy and strenghened sanction and regulation powers.