The periodic table of tap water threats.
Every contaminant worth understanding — what it is, where it comes from, what the science actually says, the legal limit, EWG's health-protective guideline, and exactly which filter types remove it.
Lead
A neurotoxic metal that leaches from old pipes and solder. No safe level for children.
Industrial contaminants.
Synthetic chemicals from manufacturing, firefighting foam, and plastics that drift into water tables.
PFAS (Forever Chemicals)
A class of ~15,000 synthetic chemicals that don't break down. Now regulated for the first time.
Chromium-6 (Hexavalent Chromium)
The Erin Brockovich chemical. A known carcinogen with no federal-specific limit yet.
Microplastics
Tiny plastic fragments now detected in nearly all tap water. Health effects still under investigation.
Disinfectants.
Chlorine and chloramine — necessary for safety, but with their own tradeoffs in long-term exposure.
Disinfection byproducts.
Compounds formed when disinfectants react with organic matter — many are probable carcinogens.
Agricultural runoff.
Fertilizer-derived nitrate, pesticides, herbicides. Heaviest in farming corridors and well water.
Naturally occurring.
Fluoride, geologic arsenic, radon — present in source water before any human input.
Pharmaceuticals.
Drug residues passing through wastewater treatment. Levels are tiny; long-term effects largely unknown.