Lead is a neurotoxin and can leach from pipes, plumbing, fixtures, and solder, before entering drinking water. According to all major U.S. health agencies, there is no safe level of lead for children, and any concentration can cause developmental issues.

Chromium 6 (The Erin Brockovich Chemical) is a known human carcinogen, but is not regulated by EPA. It can be found in both groundwater and surface water near various industrial processes, including; steel plating, chromate production, munition manufacturing, and metal plating.

Chloramine is a disinfectant used to kill bacteria and biological contamination in tap water. While chloramine is not toxic, it makes water taste bad and is not removed by most water filters.

Arsenic is a heavy metal that naturally occurs in bedrock, so some areas of the country are susceptible to arsenic contamination. Areas of the country with elevated levels of arsenic have some of the highest rates of bladder cancer in the country.

Per and Polyfluoroalkyl Substances (PFAS) are a category of man made chemicals that are almost ubiquitous is U.S. tap water. PFASand synthetic chemical exposure has been linked to an increased risk of cancer, increased cholesterol, hormonal changes, and development issues.

Chlorine is a popular disinfectant used to kill bacteria and biological contamination in tap water. While not harmful on its own, chlorine can make drinking water taste and smell unpleasant.