International drinking water standards like WHO Drinking Water Standards, EPA Drinking Water Standards, Indian Drinking Water Standards BIS-10500 are set by Government Organisations. Shown below is a table of the Indian Water Quality Standards.
The World Health Organisation's - WHO website has a wealth of information and those interested should visit their website. WHO's Guidelines for Drinking-water Quality was set up in Geneva in 1993. These standards are the international reference point for for drinking water standards. For India these standards are set by the Bureau of Indian Standards - BIS, the erstwhile Indian Standards Institute – ISI. The relevant BIS standard is BIS: 10500 available from the BIS site www.bis.org.in
For those of you interested in seeing the American Water Standards set by the internationally famous Environmental Protection Agency - the EPA Water Quality Standards, please visit the EPA site
Here below please find a copy of the main parameters set by the Indian Drinking Water Standards authority known as the BUREAU OF INDIAN STANDARDS.
The table above is sometimes modified by the Government of India. So for the latest Indian Standards for drinking water it is recommended to visit their website