Drinking water Technology, Eawag, developed a method by which hazard maps could be produced for geogenic toxic substances in groundwater. This provides an efficient way of determining which wells should be tested. Parameters for drinking water quality typically fall within three categories: Physical and chemical parameters include heavy metals, trace organic compounds, total suspended solids (TSS), and turbidity. Microbiological parameters include Coliform bacteria, "E. coli", and specific pathogenic species of bacteria (such as cholera-causing "Vibrio cholerae"), viruses, and protozoan parasites. Chemical parameters tend to pose more of a chronic health risk through buildup of heavy metals although some components like nitrates/nitrites and
Safe Drinking Water Act radium and uranium. EPA proposed regulations for radon in 1991 and 1999. Secondary drinking water standards are non-regulatory guidelines for aesthetic characteristics, including taste, color, and odor. EPA issues "health advisories" for some contaminants; some of which have not been regulated with MCLs. Health advisories provide technical information to public health officials about health effects, methods for chemical analysis, and treatment methods. The advisories are not enforceable. However, they were codified in the Safe Water Drinking Act amendments of 1996. As of 2017, health advisories have been issued for the following contaminants. The SDWA requires EPA to identify and list