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
History of municipal treatment of drinking water clean water from outside the city. The New River was slow flowing, which helped to increase sedimentation. It also had screens installed every few miles to catch any debris and weeds. These screens required periodic maintenance and workmen were employed to clean them and cut back the weeds. The new river would meet London's needs well enough that there were few complaints before the 19th century, although the water supplied was rarely used for drinking directly, rather it was more likely used for washing or the brewing of beer. By the beginning of the 19th century filtration became a means