Well water in Fairfield County, CT: what to know and what to test for

Bottom line

About11,400people on private wells may have arsenic above the drinking water limit of 10 micrograms per liter (likely 7,700 to 16,800).

Among the higher estimated numbers of affected well users in Connecticut.

Indoor radon potential: High

How to read these numbers

USGS estimate based on 2010 population, published 2017.

Connecticut advises well owners to compare their results to this limit.

Larger counties have more well users, so higher counts don't mean any one well is more likely to be affected.

EPA zone for indoor air. It doesn't measure your well water.

The Connecticut Department of Public Health recommends these tests for every private well.

Test	How often
Basic indicators (bacteria, nitrate, pH, iron and other common measures)	Every year, and after any repair to your well, pump or pipes, or if your well head floods
Arsenic, uranium and radon in water	At least once, ideally every 5 years
Lead	At least once; also if you're planning a pregnancy or have a child under 6; every 3 to 5 years if your water is corrosive
Volatile organic compounds (VOCs: gasoline, oil, solvents)	At least once; more often if a problem is suspected
Fluoride	Every 5 years when a child under 12 lives in the home

Questions about testing or treatment? Call the CT DPH Private Well Program at (860) 509-8401.