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Parameters to monitor quality

Parameters for drinking water quality typically fall within three categories: microbiological, chemical, physical.

Microbiological parameters include coliform bacteria, E. coli, and specific pathogenic species of bacteria (such as cholera -causing Vibrio cholerae), viruses, and protozoan parasites. Originally, fecal contamination was determined with the presence of coliform bacteria, a convenient marker for a class of harmful fecal pathogens. The presence of fecal coliforms (like E. Coli) serves as an indication of contamination by sewage. Additional contaminants include protozoan oocysts such as Cryptosporidium sp., Giardia lamblia, Legionella, and viruses (enteric). Microbial pathogenic parameters are typically of greatest concern because of their immediate health risk.

Physical and chemical parameters include heavy metals, trace organic compounds, total suspended solids, and turbidity. Chemical parameters tend to pose more of a chronic health risk through buildup of heavy metals although some components like nitrates/nitrites and arsenic can have a more immediate impact. Physical parameters affect the aesthetics and taste of the drinking water and may complicate the removal of microbial pathogens.

Pesticides are also potential drinking water contaminants of the category chemical contaminants. Pesticides may be present in drinking water in low concentrations, but the toxicity of the chemical and the extent of human exposure are factors that are used to determine the specific health risk.

Perfluorinated alkylated substances (PFAS) are a group of synthetic compounds used in a large variety of consumer products, such as food packaging, waterproof fabrics, carpeting and cookware. PFAS are known to persist in the environment and are commonly described as persistent organic pollutants. PFAS chemicals have been detected in blood, both humans and animals, worldwide, as well as in food products, water, air and soil. Animal testing studies with PFAS have shown effects on growth and development, and possibly effects on reproduction, thyroid, the immune system and liver. As of 2022 the health impacts of many PFAS compounds are not understood. Scientists are conducting research to determine the extent and severity of impacts from PFAS on human health. PFAS have been widely detected in drinking water worldwide and regulations have been developed, or are under development, in many countries.