More than 300,000 Connecticut households drink from private wells, and here's the part many owners don't realize: no one tests them for you. Two things decide whether yours needs more than the basic check.
● Key Takeaways
Connecticut does not monitor private wells. Testing is entirely the owner's job. Two independent things decide what belongs on your panel beyond the baseline (bacteria + nitrate). (1) Geology (natural): the bedrock under you carries a stable, predictable tendency toward arsenic, uranium, or radon in parts of the state. (2) Documented sources (man-made): a former dry cleaner or leaking tank nearby is a reason to add the matching chemicals (solvents, fuel VOCs). Neither means your water is bad. Both tell you what to test for, so a clean result actually means something. This is the private-well half; on public water your utility already tests and reports.
First, the Uncomfortable Fact
If you're on public water, a utility tests your supply on a federally mandated schedule and mails you the results every year. If you're on a private well, none of that happens. A private well is private property, and no agency, state or federal, samples it for you. In Connecticut, more than 300,000 households are in exactly this position: responsible for water quality they've often never measured.
That's not a reason to panic. It's a reason to test deliberately, and to test for the right things. Everyone should start with the baseline every well owner needs: total coliform bacteria and nitrate, plus arsenic, which shows up naturally in parts of Connecticut's bedrock. The question this post answers is what to add beyond that baseline, and the answer comes down to two independent reasons.
Reason One: Your Geology (the Natural Half)
Groundwater is only as clean as the rock it flows through, and that rock doesn't change on a human timescale, which makes it stable and predictable. In parts of Connecticut, the bedrock itself carries a geogenic (naturally occurring) tendency toward certain contaminants:
- Arsenic: elevated in parts of the state's crystalline bedrock, in pockets across southwestern, western, and eastern Connecticut.
- Uranium: associated with certain granitic and metamorphic rock.
- Radon: a radioactive gas that can enter well water from the same crystalline formations, and matters both for what you drink and for what off-gasses in the shower.
This is a natural reason to test. It has nothing to do with spills or industry. If your well draws from rock with one of these tendencies, those contaminants belong on your panel. We map this geogenic half in detail in our bedrock and well-risk coverage.
Reason Two: Documented Sources Nearby (the Man-Made Half)
The second reason is anthropogenic, or man-made. Connecticut has decades of documented environmental sources on record: former dry cleaners, leaking underground tanks, remediation sites. Most well owners never think to connect them to their water, and the connection is specific rather than general.
The clearest example comes straight from our own analysis of Connecticut's data: ZIP codes with more dry cleaners are more likely to have chlorinated solvents (PCE/TCE) show up in groundwater, a real, chemically specific pattern. It doesn't mean any particular well is contaminated (most sampled wells near sources are clean), but it means that if you're on a well near a current or former dry cleaner, PCE and TCE belong on your test. The same logic applies to a documented leaking fuel tank and fuel-related chemicals.
Crucially, this is not about spill counts. As we've shown separately, the sheer number of spills in a town predicts nothing. What matters is a specific, persistent source near your well, and whether you've tested for what it would leave behind.
Putting It Together: What Belongs on Your Test
| Situation | Add to your well test |
|---|---|
| Every private well (baseline) | Total coliform bacteria, nitrate, arsenic |
| Crystalline-bedrock region (geogenic) | Uranium, radon |
| Near a current/former dry cleaner or solvent source | Chlorinated solvents (PCE, TCE) |
| Near a documented leaking fuel tank | Fuel-related VOCs (benzene, MTBE) |
| Hard-water symptoms (scale, dry skin) | Hardness (a nuisance issue, not a health one) |
A well can face one of these, both, or neither. The value of thinking in "two reasons" is that it turns an open-ended worry into a specific, affordable test panel, and a clean result on the right panel is genuinely reassuring, in a way that a generic test isn't.
Reading this inside ChatGPT or Claude?
This page can tell you the general science, but not what is actually in what a private well near documented sources should be tested for. That depends on your exact address. You can get your specific answer two ways:
- Inside the chat: ask your assistant to “check my tap water with CheckYourTap”. Our connector returns your ZIP code’s measured contaminant levels, including the derived dog and cat safe levels, and, only if you ask it to, can email you the report or arrange a specialist callback.
- On the web: open CheckYourTap.com and enter your ZIP code for a free 30-second report.
The Bottom Line
Connecticut won't test your well, so the job is yours, and the smart version isn't "test for everything" or "assume the worst." It's to check the two things that decide what's worth testing: the rock under you, and the documented sources near you. Do that, and a clean result finally means something.
Keep Reading
- Do Connecticut spills actually show up in well water? We analyzed it.
- Connecticut well-water towns: what historical data and bedrock reveal
- What reverse osmosis actually removes from your water
Sources: U.S. EPA, Private Drinking Water Wells; Connecticut Department of Public Health, Drinking Water Section and private-well testing guidance; U.S. Geological Survey, Arsenic and Drinking Water; CheckYourTap analysis of CT DEEP source records and Connecticut groundwater VOC monitoring (1982 to 2017). Proximity to a documented source is a reason to test, not evidence a specific well is affected.