Well water contaminants
The full list of things your test panel should check for — and why.
Private well water can contain contaminants from three sources: the geology the water moves through, what people do on the land above, and what's inside your pipes. Below is the full roster we cover, with health context, testing guidance, and what actually works to treat each one.
Naturally occurring metalloid that contaminates groundwater across much of the US, especially the West and parts of New England. Causes cancer, cardiovascular d…
Radioactive gas that dissolves in groundwater from uranium-bearing rock. Enters your home through every tap. Significant cause of lung cancer in the US.
Agricultural fertilizer and septic-derived contamination of shallow groundwater. The dominant rural well concern in irrigated farm country. Acute risk to infant…
The most common nuisance contaminants in private wells: rust stains, black stains, metallic taste. Iron is genuinely cosmetic. Manganese is increasingly recogni…
Per- and polyfluoroalkyl substances. Synthetic chemicals invented in the 1940s, used in firefighting foam, non-stick coatings, water-repellent fabrics. They don…
Heavy metal that dissolves into groundwater from uraniferous rock — granite, certain sandstones, weathered volcanic terrain. Causes kidney damage at chronic e…
Total coliform and E. coli are the standard indicators that surface water, septic effluent, animal waste, or fecal contamination has reached your well. The most…
Lead doesn't naturally occur in groundwater at concerning levels. It enters drinking water from lead solder (legal until 1986), lead service lines (mostly histo…
Calcium and magnesium dissolved from carbonate and sulfate rock. Universal in carbonate-aquifer regions (Floridan, Edwards, Cambrian-Ordovician, High Plains). N…
Hexavalent chromium, Cr(VI). Distinct from trivalent chromium Cr(III), which is essential for human metabolism — Cr(VI) is a potent carcinogen. Naturally occu…
When coastal aquifers are pumped faster than they recharge, the freshwater pressure that holds the ocean back drops, and the seawater wedge moves inland. Tested…
Naturally occurring in groundwater from fluorite, fluorapatite, and weathered volcanic rocks. Hot zones across the western US, parts of Texas, and the High Plai…
Volatile organic compounds — benzene from gasoline, PCE/TCE from dry cleaners, MTBE legacy contamination, vinyl chloride from solvent breakdown. Almost always…
Agricultural chemicals — atrazine, glyphosate, simazine, neonicotinoids, plus banned-but-persistent compounds like DBCP, 1,2,3-TCP, and chlordane. Most are de…
Naturally occurring radioactive metal — Ra-226 from the uranium decay chain, Ra-228 from the thorium decay chain. Concentrates in bone (chemically similar to …
The unmistakable rotten-egg odor in some well water. Caused by sulfate-reducing bacteria converting natural sulfate to H₂S in low-oxygen aquifer conditions, o…
Naturally occurring inorganic anion from gypsum, anhydrite, pyrite oxidation, and seawater. Hot zones include the Dakotas, parts of Texas and Kansas, gypsum-bea…