I Have a Private Well: Your Annual Testing Schedule

The thing nobody told you when you bought a well

Public water systems are tested constantly. Private wells — about 13 million of them in the U.S. — are tested only when the owner chooses to. There is no annual inspection, no required CCR, and no agency calling to remind you. The EPA's official recommendation is that every private well be tested annually, and roughly two-thirds of well owners don't.

If you're reading this, you're already ahead. Here's what to actually test, and when.

Every year

Total coliform bacteria — the indicator that something has entered your well from above. Positive doesn't mean dangerous, but it means investigate.

E. coli — specific to fecal contamination. A positive E. coli result means stop drinking the water and act immediately.

Nitrate and nitrite — most relevant for households with pregnant people, infants, or anyone on a low-sodium diet. The EPA limit is 10 mg/L as nitrogen.

pH and total dissolved solids — useful as a baseline. Sudden changes here often precede problems.

Every three years

Heavy metals — arsenic, lead, copper, and iron/manganese. Arsenic in particular is invisible and tasteless, and regional geology matters more than well age.

VOCs — volatile organic compounds, especially if you're within a few miles of a gas station, dry cleaner, or industrial site.

Radon in water — for wells in radon-prone regions, separate from indoor air radon testing.

Trigger events: test now, regardless of schedule

Any of these warrant immediate testing: a new neighbor began farming or building nearby, a flooding event or heavy spring runoff, a pressure loss or repair on the well, a change in taste, smell, or color of the water, a household member developing unexplained GI or skin symptoms, or any local advisory from your county health department.

Why "my water tastes fine" isn't the answer

Every contaminant on the annual list above is undetectable to your senses at the levels that matter for your health. Arsenic, nitrates, and E. coli all show up in water that tastes perfect. The test is the point.