How often should I test my private well in Connecticut?

The Connecticut Department of Public Health recommends a basic indicators test (bacteria, nitrate, nitrite, sodium, chloride, iron, manganese, hardness, pH and others) every year, and again after any repair to the well, pump or pipes or if the wellhead floods. It recommends testing for arsenic, uranium and radon at least once and ideally every 5 years, for lead and volatile organic compounds at least once, and for fluoride every 5 years when a child under 12 lives in the home.

Is well testing required when you buy a house in Connecticut?

Not by state law. CT DPH says water tests during home purchases are usually required by the bank holding the mortgage, not by law, and those tests do not necessarily cover all contaminants. Since October 1, 2022, arsenic and uranium testing has been required for newly drilled wells, but existing wells are not routinely tested. CT DPH highly recommends testing when you buy a home with a well.

Where do I get my well water tested in Connecticut?

At any laboratory certified by CT DPH to test drinking water for the contaminants you want measured. CT DPH's Environmental Laboratory Certification Program publishes the current list, with columns showing which labs accept private well samples and which test arsenic, uranium, radiological analytes and PFAS. Radon in water should be collected by a nationally certified radon measurement professional and analyzed by a DPH-approved lab.

How much does a well water test cost in Connecticut?

Prices vary by laboratory and panel. A 2021 Connecticut state workgroup estimated a standard potability test at about $150, an arsenic analysis at about $25 and a uranium analysis at about $100 per sample. Ask the laboratory for its current price list before sampling.

What should I do if my well test comes back high?

CT DPH says to retest to confirm the result, stop drinking the water until the issue is resolved, contact your local health department or the CT DPH Private Well Program, and consider treatment designed for that specific contaminant. Some results, such as iron or hardness, are aesthetic limits rather than health limits, so check which kind of limit was exceeded.

Private Well Testing in Connecticut: The Complete Guide

In Connecticut, nobody tests a private well except its owner. The state Department of Public Health (CT DPH) recommends a basic indicators test every year, arsenic, uranium and radon at least once (ideally every five years), and lead and volatile organic compounds at least once, all through a state-certified laboratory (CT DPH, updated May 2026).

● Key Takeaways

About 342,356 private wells serve more than 837,000 people, roughly 23% of Connecticut. Federal drinking water rules do not cover them. CT DPH's schedule: basic indicators yearly; arsenic, uranium and radon at least once, ideally every 5 years; lead and VOCs at least once. Use a CT DPH-certified lab, compare results with CT DPH Action Levels and EPA limits, and retest before acting on a high number.

Who Is Responsible for Testing a Connecticut Well?

You are. CT DPH estimates there are about 342,356 private residential wells in the state serving more than 837,000 people, about 23% of the population, and says private wells supplying homes "are not currently regulated" by the EPA (CT DPH Private Wells). The EPA says the same thing from the federal side: private domestic wells are not regulated under the Safe Drinking Water Act (EPA).

State law requires testing of new wells, but CT DPH notes that the required tests "do not cover all contaminants" (CT DPH). Since October 1, 2022, arsenic and uranium have been part of that new-well testing (CT DPH arsenic; CT DPH uranium). A well drilled before then may never have been checked for either.

Home sales are the other gap. CT DPH says water tests during a purchase are usually required by the mortgage lender, "not required by law," and do not necessarily cover all contaminants. A cash buyer may never test at all. A 2021 state workgroup, citing complaints from owners who found uranium and radon after closing, recommended adding arsenic and uranium to new-well tests and requiring potability testing at every sale of a home on a well (CT Water Planning Council workgroup, June 2021). New wells now include arsenic and uranium, as noted above. CT DPH's current guidance still describes purchase testing as a lender requirement rather than a legal one.

What Should I Test For, and How Often?

CT DPH's Table 1 is the schedule for every private well, "even if you do not notice any problems" (CT DPH, updated May 2026):

Test	How often (CT DPH)	Why
Basic indicators	Every year, and after well, pump or pipe repairs or a flooded wellhead	General water quality; required for new wells
Lead (first-draw and flushed samples)	At least once; also when planning a pregnancy or with a child under 6; every 3 to 5 years if water is corrosive	Leaches from household plumbing
Arsenic, uranium, radon	At least once; ideally repeat every 5 years	Occur naturally in groundwater in parts of CT; levels may fluctuate
Volatile organic compounds (VOCs)	At least once; more often if a problem is suspected	Fuel, oil, solvent or industrial spills
Fluoride	Every 5 years when a child under 12 lives in the home	Occurs naturally; affects children's teeth

CT DPH adds that a good time to test is after heavy rain, typically in spring or fall, and that testing is "highly recommended" when buying a home.

What Is in a Basic Indicators Test?

The basic indicators panel is the yearly test. CT DPH lists these parameters and the standard each is compared against:

Total coliform bacteria: none present
Nitrate: 10 mg/L; nitrite: 1 mg/L
Sodium: 100 mg/L; chloride: 250 mg/L; sulfate: 250 mg/L
Iron: 0.3 mg/L; manganese: 0.05 mg/L (aesthetic) and 0.3 mg/L (health)
pH: 6.5 to 8.5; turbidity, apparent color, odor
Hardness: reported as soft (0 to 60), moderately hard (61 to 120), hard (121 to 180) or very hard (over 181)

Some of these limits protect health, such as bacteria, nitrate and the higher manganese level. Others, such as iron, color and odor, are about taste, staining and appearance. That distinction matters when you read a result.

When Should I Test Outside the Schedule?

CT DPH's troubleshooting table ties specific situations to specific tests. A few that come up often in Connecticut:

A change in taste, color, odor or clarity: contact your local health department or the CT DPH Private Well Program.
Radon in indoor air above 4 pCi/L, or uranium in water above 30 µg/L: test for uranium, radium and radon.
Well within a quarter mile of a current or former orchard or farm: nitrate, arsenic and pesticides (CT DPH suggests asking about EPA Method 505).
Well within a quarter mile of a commercial or industrial area, or a fuel or chemical odor: VOCs.
Recurring stomach illness, flooding, or ponding around the well: coliform bacteria, nitrate and nitrite.
Salty taste near roads or salt storage: chloride, sodium and total dissolved solids.
Foundation treated for termites before 1990: the pesticides dieldrin and chlordane.

If you already have a treatment system, CT DPH recommends testing for the contaminant it treats, before and after the system, to confirm it still works.

Why Arsenic, Uranium and Radon Get Special Attention in Connecticut

All three come from rock, not from anything a homeowner did. A U.S. Geological Survey study done with CT DPH analyzed 2,433 well samples for arsenic and 2,191 for uranium from 2013 to 2018. In its spatially weighted analysis, 3.9% of samples had arsenic above the EPA limit of 10 µg/L and 4.7% had uranium above the EPA limit of 30 µg/L. Uranium at 1 µg/L or more was present across about 44.9% of the state (USGS Open-File Report 2020-1111).

USGS found that exceedances cluster in certain bedrock units: 44 of the 115 geologic units it studied had at least one sample over a limit. That is why neighbors on different rock can get very different results. Our arsenic and uranium by region guide lists the units with the highest rates and the towns where they are mapped.

Radon comes from the decay of uranium. CT DPH recommends testing well water for radon in every home on a well, because water can carry radon even when indoor air tests low (CT DPH, revised February 2025). Our radon in Connecticut well water guide covers the state's 5,000 pCi/L action level and treatment.

How Do I Find a Certified Lab?

Use a laboratory certified by CT DPH to test drinking water for the specific contaminants you want measured (CT DPH). The Environmental Laboratory Certification Program publishes the current list of in-state labs certified for drinking water. Its columns show which labs accept private well samples and which are certified for bacteria, inorganics (including arsenic), organic chemicals, PFAS, radiological analytes and uranium. Not every certified lab takes private well samples, so check that column first.

A few practical points from CT DPH:

Follow the lab's sampling instructions exactly. Lead and copper may need water that sat in the pipes at least six hours (a first draw); other tests need the tap flushed first. Some need special bottles, most must stay cool, and all have a time limit for reaching the lab.
For uranium, CT DPH suggests asking for a uranium test by ICP-MS, which it describes as quicker and less expensive than alternatives (CT DPH uranium fact sheet).
For radon in water, CT DPH recommends a qualified radon measurement professional to collect the sample and a DPH-approved lab to analyze it (CT DPH Radon in Water).
For arsenic above the limit, CT DPH suggests asking about arsenic III testing before choosing treatment, because arsenic III is harder to remove (CT DPH arsenic).

What Does Well Testing Cost in Connecticut?

It depends on the lab and the panel, so ask for a current price list before you sample. As a public reference point, the 2021 state workgroup estimated a standard potability test at about $150, an arsenic analysis at about $25 per sample, and uranium at about $100 per sample (CT Water Planning Council workgroup, June 2021). Those are 2021 estimates, not quotes.

Treatment, if a test calls for it, costs more. For radon in water, CT DPH's 2025 fact sheet puts a granular activated carbon system at $1,500 to $3,500 installed and an aeration system at an average of $5,000 to $7,000 (CT DPH, revised February 2025).

How Do I Read My Well Test Results?

Compare each result with two sets of numbers (CT DPH):

CT DPH Action Levels, health-based levels the state sets for private wells (Action Level List). Arsenic's Action Level is 10 µg/L, the same as the EPA limit.
EPA Maximum Contaminant Levels (MCLs), the federal health limits for public water, such as 30 µg/L for uranium. EPA's secondary limits (SMCLs) cover taste, color and odor, not health.

Check the units on the report. Micrograms per liter (µg/L) equal parts per billion (ppb); milligrams per liter (mg/L) equal parts per million (ppm), and 1 mg/L is 1,000 µg/L. Radon is reported in picocuries per liter (pCi/L).

If any result is above an Action Level or MCL, CT DPH says to:

Retest to confirm the exceedance.
Stop drinking the water until the issue is resolved.
Contact your local health department (find yours) or the CT DPH Private Well Program at (860) 509-8401.
Consider treatment designed for that contaminant.

For arsenic and uranium, which matter mainly when swallowed, CT DPH notes that a point-of-use system at the tap used for drinking and cooking is often enough (CT DPH arsenic; CT DPH uranium). Radon is different: most of its risk comes from breathing gas released into the air, so treatment goes on the whole house.

Keep every report with its date. A rising number over time can flag a developing problem or a treatment system that has stopped working.

Town Guides

We are publishing town-level well guides that pair this schedule with the public bedrock and groundwater record for each town:

Ready to test your well?

A water specialist can arrange certified lab testing for your well, starting with the tests CT DPH recommends.

CheckYourTap is an independent water-quality service, not your town or utility. We connect you with a vetted local partner. Your online report is free. Testing and treatment are paid services, and there's no cost to talk.

Keep Reading

Sources: CT DPH, Educational materials: testing recommendations for private wells (updated May 2026); CT DPH Private Wells; CT DPH, Arsenic in private well water; CT DPH, Uranium in Private Well Water (April 2024); CT DPH, Radon in Your Well Water (revised February 2025); CT DPH, Radon in Water; CT DPH Action Level List; CT DPH Environmental Laboratory Certification Program; Recommendations for water quality testing of private and semipublic wells, CT Water Planning Council workgroup (June 2021); Gross and Brown, USGS Open-File Report 2020-1111; EPA, Private Drinking Water Wells.

About this guide: CheckYourTap is an independent water-quality service funded by Valiant Energy Solutions, a Connecticut water quality and energy services company established in 1930. Valiant offers paid well testing and treatment, which is what the request button on this page connects you with. You can also contact any CT DPH-certified laboratory directly. The facts on this page come from the public sources cited above.

Private Well Testing in Connecticut: What to Test, How Often, and How to Read the Results