The National Primary Drinking Water Regulations (NPDWR) are legally enforceable primary standards and treatment techniques that apply to public water systems. Primary standards and treatment techniques protect public health by limiting the levels of contaminants in drinking water.
GEMS/Water is part of the United Nations environment programme.
For water quality recommendations, see the 2007 "Global Drinking Water Quality Index Development and Sensitivity Analysis Report": https://www.un.org/waterforlifedecade/pdf/global_drinking_water_quality_index.pdf.