Water Contaminant Guide

A toxic heavy metal that leaches into drinking water primarily from aging lead service lines, lead solder (common in homes built before 1986), and brass fixture…

Per- and polyfluoroalkyl substances (PFAS) are a group of over 12,000 man-made chemicals used in non-stick cookware coatings, firefighting foam (AFFF), food pac…

Chlorine is intentionally added to municipal water supplies as a disinfectant to kill bacteria, viruses, and other pathogens. While essential for public health,…

Chloramine is formed when water utilities add ammonia to chlorinated water as an alternative disinfectant. It's more stable than free chlorine and lasts longer …

Arsenic is a naturally occurring metalloid found in rock and soil formations. It dissolves into groundwater through natural geological processes, and is also re…

Nitrates are nitrogen-oxygen compounds that enter groundwater primarily from agricultural fertilizers and animal waste. They are a leading cause of water contam…

Hexavalent chromium (Chromium-6) is a toxic industrial chemical made famous by the Erin Brockovich case in Hinkley, CA. It enters water from industrial discharg…

Fluoride is intentionally added to public water supplies at low levels (0.7 mg/L) to prevent tooth decay. At this level it is considered safe. However, excessiv…

Trihalomethanes form when chlorine used to disinfect water reacts with naturally occurring organic matter (decomposed plant material, algae). The four most comm…

Coliform bacteria, including E. coli, are indicators of fecal contamination in water. Their presence means sewage, animal waste, or other contamination may have…

Microplastics are tiny plastic particles less than 5mm in size. They come from the breakdown of larger plastic waste, synthetic fibers from laundry, cosmetic mi…

Copper enters drinking water primarily from corrosion of household copper plumbing pipes and fittings. It is most problematic in new plumbing (before a protecti…

Radionuclides are unstable atoms that emit radiation as they decay. In drinking water the ones EPA regulates most often are uranium, combined radium-226 and rad…

This group includes synthetic organic chemicals used in farming, turf management, and pest control that can reach groundwater and surface water through runoff, …

VOCs are carbon-based chemicals that evaporate easily at room temperature. In drinking water, common examples include benzene, trichloroethylene (TCE), tetrachl…

These are microscopic parasites that form tough cysts (Giardia) or oocysts (Cryptosporidium) that survive in cold water. They cause gastrointestinal illness and…