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

Bottom line

About6,800people on private wells may have arsenic above the drinking water limit of 10 micrograms per liter (likely 4,600 to 9,800).

In the middle range for Connecticut.

Indoor radon potential: High

Connecticut recommends testing every private well for arsenic, uranium and radon at least once.

Find a certified lab
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.

What to test for

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

TestHow 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 waterAt least once, ideally every 5 years
LeadAt 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
FluorideEvery 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.

Source: Connecticut Department of Public Health, Educational Materials on private well testing (updated May 2026)

Where to test

Certified labs in New Haven County that accept private-well samples.

Aquatek Labs, Inc.

Woodbridge

Certified for

  • Arsenic
  • Bacteria
  • Minerals and metals (inorganics)
  • Fuel and chemical compounds (organics)
  • Radioactive elements (radiological)
  • Uranium

Call to request a private well test kit and price.

(203) 389-1824

Environmental Consulting Lab

Madison

Certified for

  • Arsenic
  • Bacteria
  • Minerals and metals (inorganics)
  • Uranium

Call to request a private well test kit and price.

(203) 245-0568

EMSL Analytical, Inc. - CT

Meriden

Certified for

  • Asbestos
  • Bacteria

Call to request a private well test kit and price.

(203) 284-5948

Environmental Monitoring Lab

Wallingford

Certified for

  • Arsenic
  • Bacteria
  • Minerals and metals (inorganics)
  • Fuel and chemical compounds (organics)

Call to request a private well test kit and price.

(203) 284-0555

Northwest Environmental Water Labs

Waterbury

Certified for

  • Arsenic
  • Bacteria
  • Minerals and metals (inorganics)

Call to request a private well test kit and price.

(203) 437-4110

Regional Water Authority

New Haven

Certified for

  • Arsenic
  • Bacteria
  • Minerals and metals (inorganics)
  • Fuel and chemical compounds (organics)
  • PFAS

Call to request a private well test kit and price.

(203) 401-2700

These are the test groups marked yes for that lab. A yes means the lab is certified for some or all of the tests in that group.

Lab list current as of October 9, 2026, from the Connecticut Department of Public Health.

Sources