PPT Slide
Mandatory national drinking water standards are required by the Safe Drinking Water Act of 1974. The standards seek to protect the public from health risks (carcinogenic and non-carcinogenic toxicity) associated with long term use of a drinking water. Standards take the form of maximum contaminant levels (MCLs), now established for 15 metals and more than 50 organic chemicals, e.g. benzene (0.005 ppm) and dioxin (0.00000003 ppm).