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
Drinking water (in decreasing order) toilets, washing machines, showers, baths, faucets, and leaks. Any public water system, which is defined as a system that serves more than 25 customers or 15 service connections, is regulated by the U.S. Environmental Protection Agency under the Safe Water Drinking Act based on minimum contaminant levels the agency sets. In some parts of the country water supplies are dangerously low due to drought and depletion of the aquifers, particularly in the West and the South East region of the U.S. The drinking water in Canada's cities is regularly tested and considered safe, but on many native