If your home runs on a private well, here is the single most important thing to know: no one is testing your water but you.
More than 23 million U.S. households rely on private wells, and the EPA does not regulate them. The Safe Drinking Water Act — the federal law that forces your city's utility to test, treat, and report on its water — stops at the property line. Whatever comes out of your well is your responsibility.
Why well water goes wrong
Well water quality isn't determined by a treatment plant. It's determined by your local geology and what happens on the land around you. That means two wells a mile apart can produce completely different water.
The most common issues fall into three groups:
1. Microbial contamination
Coliform bacteria and E. coli can enter a well from septic systems, livestock, runoff, or a compromised well cap. You cannot taste or smell them. This is the reason annual testing exists.
2. Nitrates
Fertilizer runoff and septic leachate drive nitrates into groundwater, especially in agricultural areas. The federal health limit for public systems is 10 mg/L (as nitrogen) — above that, nitrate interferes with how blood carries oxygen, and infants are at particular risk. Boiling water does not remove nitrates; it concentrates them.
3. Geology-driven contaminants
Depending on your region: arsenic, radon, uranium, iron, manganese, and hydrogen sulfide (the rotten-egg smell). None of these announce themselves at dangerous levels — iron stains your fixtures long before arsenic ever shows a symptom.
What to test, and how often
The EPA's guidance for private well owners is to test at least once every year for total coliform bacteria, nitrates, total dissolved solids (TDS), and pH — and immediately after flooding, land disturbance nearby, any repair to the well, or any change in taste, odor, or color.
Every few years, or when you move into a home with a well, run a broader panel that covers arsenic, lead, iron, manganese, and hardness. Your county health department can tell you which contaminants are common in your area, and many offer low-cost testing.
What to do with the results
Treatment should match the data — not the other way around. Bacteria calls for disinfection (UV or chlorination). Nitrates call for reverse osmosis or ion exchange. Iron and manganese call for oxidizing media filters. Hardness calls for a softener. A single system rarely solves everything, which is why whole-house well setups are usually staged: sediment first, then the specific problem, then polishing.
If you have a recent test report and aren't sure what it means, send it to us at contact@reinwaterusa.com — we'll read it with you and tell you honestly whether it warrants treatment. If you don't have a report yet, start with a test kit, not a filter. See our water testing tools and well water systems.