United States standards[edit]

In the USA, the federal legislation controlling drinking water quality is the Safe Drinking Water Act (SDWA) which is implemented by the EPA, mainly through state or territorial primacy agencies. States and territories must implement rules that are at least as stringent as EPA's to retain primary enforcement authority (primacy) over drinking water. Many states also apply their own state-specific standards, which may be more rigorous or include additional parameters. Standards set by the EPA in the USA are not international standards since they apply only to a single country, however, many countries look to the USA for appropriate scientific and public health guidance and may reference or adopt USA standards.

World health Organisation Guidelines[edit]

The World Health Organisation (WHO) Guideline for Drinking-water Quality (GDWQ) include the following recommended limits on naturally occurring constituents that may have direct adverse health impact: