Water legislation in the EU is based on the Council Directive 98/83/EC of November, 3, 1998 on the quality of water intended for human consumption; Official Journal L 330, 05/12/1998, p.0032-0054.

Parameters and parametric values are presented in Annex I: http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:1998:330:0032:0054:EN:PDF