Quick answer
About 673,000 people in Connecticut (18.8% of residents) got their water from private wells in 2010, according to USGS estimates. Connecticut Department of Public Health runs the state’s private well guidance. We didn’t find a free statewide well testing program in Connecticut. Certified labs charge for each test, and some county health departments offer lower-cost bacteria and nitrate tests.
- People on private wells
- 672,792
- Share of residents
- 18.8%
- Rank among states
- 21st
- Well users modeled above 10 µg/L arsenic
- 8.3%
Where to get your well tested in Connecticut
- Connecticut Department of Public Health: Private Well Water Program, the state’s guidance for private well owners.
- Well water testing in Connecticut: what to test for and how to collect a sample.
- Certified laboratories in Connecticut. Use a lab certified for drinking water, so results are reliable.
Free or low-cost testing
We didn’t find a free statewide program in Connecticut. Certified labs charge per test; county health departments sometimes offer lower-cost bacteria and nitrate tests.
Mail-in lab kits are another option when no local lab is convenient. See well water test kits for what home kits can and can’t tell you.
What to test for
- Every year: total coliform bacteria and nitrate.
- Before buying equipment: pH, hardness, iron, manganese and, if there’s a smell, hydrogen sulfide.
- Based on location: arsenic, uranium and radon, PFAS, and lead in older plumbing.
USGS modeling estimates that about 8.3% of Connecticut’s private well users have water above the 10 µg/L arsenic limit. Arsenic has no taste or smell, so include it in your first test.
Private wells by county
Estimated people relying on private wells in each Connecticut county in 2010, the share of residents that represents, and the modeled share of well users with arsenic above 10 µg/L. These are USGS model estimates (2010 population), not measurements of any well. Arsenic is hidden for counties with fewer than 500 well users.
| County | People on wells | Share | Arsenic >10 µg/L |
|---|---|---|---|
| Fairfield County | 159,196 | 17.4% | 8.0% |
| New Haven County | 108,142 | 12.5% | 9.4% |
| Hartford County | 82,765 | 9.3% | 10.1% |
| New London County | 78,068 | 28.5% | 7.0% |
| Litchfield County | 76,536 | 40.3% | 4.6% |
| Tolland County | 63,096 | 41.3% | 9.5% |
| Windham County | 53,418 | 45.1% | 9.0% |
| Middlesex County | 51,571 | 31.1% | 9.1% |
Counties with the highest modeled arsenic share: Hartford County (10.1%), Tolland County (9.5%), New Haven County (9.4%), Middlesex County (9.1%), Windham County (9.0%).
After you get results
Enter your numbers in the test results tool to see what needs treating and in what order. The guide to reading a well water test explains units and limits.
Common questions
Does Connecticut offer free well water testing?
We didn’t find a free statewide well testing program in Connecticut. Certified labs charge for each test, and some county health departments offer lower-cost bacteria and nitrate tests.
Who oversees private wells in Connecticut?
Connecticut Department of Public Health (Private Well Water Program) publishes guidance for private well owners. Private wells aren’t covered by the federal Safe Drinking Water Act, so testing and treatment are up to the owner.
How many people use private wells in Connecticut?
USGS estimates about 673,000 people, or 18.8% of the population in 2010. That ranks 21st of the states covered by the estimate.
What should I test my well for in Connecticut?
Test every year for total coliform bacteria and nitrate, plus pH, hardness, iron and manganese before buying equipment. Arsenic is a known concern in parts of Connecticut, so add it to the first test.
Sources
- Connecticut Department of Public Health: Private Well Water Program
- Connecticut Department of Public Health: well water testing
- Connecticut certified laboratories
- USGS data release: domestic well locations and populations served, 2000 and 2010 (Johnson, Belitz and Lombard, 2019)
- CDC Environmental Public Health Tracking: private well water data (from USGS)