The quality of drinking water is defined by the regulations of the World Health Organisation (WHO), on which the Drinking Water Directive of the EU (EC-Directive 83/98) and the National Drinking Water Regulations are based. In addition there are national standards and approvals of procedures and materials in the area of drinking water, e.g. the DVGW (German Technical and Scientific Association for Gas and Water). Among other things the regulation defines the substances to be tested in drinking water and the corresponding permitted limit values (e.g. in µg/l) as well as the frequency of measurements to be carried out. One problem is that the analyses do not cover all conceivable or known contaminations.
For their known impacts on health of 200 substances the WHO requires their testing. According to the German Drinking Water Ordinance in total only 33 substances possibly contained in water are indicated with their corresponding limit values, which would have to be tested at a complete drinking water analysis. One indicator principle has, however, been implemented, by which the probability of contamination with related substances is made evaluable in groups; for example Escherichia coli represents all faecal germs and the sum of mercury, lead and cadmium stands for all heavy metals.
On the 28th of July, 2010, the UN-General Assembly, at the request of Bolivia, declared the access to clean drinking water and to basic sanitary services to be human rights. 122 countries accepted the request without any opposing votes. 41 countries abstained from voting, among them the USA, Canada and 18 EU-states.