If your dog drinks from a private well in Connecticut, arsenic is the one contaminant worth checking first. It has no taste or smell, some Connecticut wells run high, and the level that is fine for you can be too high for a puppy.
● Key Takeaways
For an adult dog, our arsenic screening level is 10 ppb, the same as the human limit, because dogs clear inorganic arsenic quickly. For a puppy, senior, or pregnant dog, we use about 3.3 ppb. In state groundwater records, private wells in Weston, Haddam, Woodstock, Westport, Somers, and Seymour have tested above 10 ppb, some far higher. Those are counts from tested wells, not every home, and many are older readings. City water is generally covered for arsenic; private wells are the real concern because no one tests them for you. If your dog is on a well in one of these towns, test it.
The Simple Version
Arsenic gets into water from rock, not from pollution, which is why it shows up in wells drilled into certain Connecticut bedrock. You cannot see it, taste it, or smell it. Over time it can cause skin problems, stomach upset, and organ strain in dogs, and puppies and seniors handle it worse than a healthy adult dog.
Here is the part most pet owners never hear. The "safe" arsenic number depends on who is drinking. For a grown, healthy dog we use 10 ppb, the same limit the EPA sets for people, because dogs break down and clear inorganic arsenic faster than the human cancer-risk math assumes. For a puppy, a senior dog with kidney trouble, or a pregnant or nursing dog, we drop that to about 3.3 ppb. Those are screening estimates we derive and label as such, not official vet standards. You can see the full reasoning on our arsenic and dogs explainer.
The Connecticut Towns Where Wells Have Run High
We reviewed Connecticut groundwater records and grouped towns by how their tested private wells compare to the dog screening levels. Read this as a map of where testing has found arsenic, not a verdict on any one house.
| Town | Highest reading found | Wells above puppy level (3.3 ppb) | Wells above adult-dog level (10 ppb) |
|---|---|---|---|
| Weston | 115 ppb | 7 of 11 tested | 4 of 11 |
| Somers | 46 ppb | 2 of 10 | 1 of 10 |
| Seymour | 38 ppb | 3 of 4 | 2 of 4 |
| Haddam | 34 ppb | 8 of 9 | 3 of 9 |
| Woodstock | 29 ppb | 7 of 7 | 3 of 7 |
| Redding | 29 ppb | 3 of 6 | 1 of 6 |
| Westport | 20 ppb | 5 of 5 | 3 of 5 |
| Meriden | 20 ppb | 2 of 5 | 1 of 5 |
| Glastonbury | 15 ppb | 2 of 5 | 1 of 5 |
| Portland | 11 ppb | 1 of 8 | 1 of 8 |
The counts are of wells that happened to get tested in each town, not of every home. One high reading does not mean the whole town is high, and a town not on this list is not automatically clean.
A second group of towns had wells above the 3.3 ppb puppy level but at or below the human limit, meaning the water is generally fine for you and a grown dog, but worth a look if you have a puppy or an older dog: Pomfret, Cheshire, Colchester, Avon, Simsbury, and Woodbury.
Two honest caveats. These are readings from wells that happened to be tested, so a town on the list is not a claim about your specific well, and a town not on the list is not a clean bill of health. And many of these readings are older, because private wells are not on a testing schedule. That is exactly why a current test of your own well is the only thing that tells you your dog's water.
Reading this inside ChatGPT or Claude?
This page can tell you the general science, but not what is actually in arsenic in well water for dogs near a Connecticut town. 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.
Why This Matters More for Dogs Than for You
Two reasons. First, dogs drink more water for their size than we do, so a level that gives a person a small lifetime risk reaches a dog faster. Second, most people on wells never test, and dogs drink whatever comes out of the tap, every day, for their whole lives. A well that has never been tested is the real gap, and your dog is the one drinking from it without a say.
What To Do
If your dog is on city water, arsenic is generally handled for you. If your dog drinks from a private well, especially in one of the towns above, test the water for arsenic. If it comes back above 10 ppb, or above 3.3 ppb and you have a puppy, senior, or pregnant dog, a reverse osmosis system is the most complete fix. Test first, then treat only what is actually high.
Keep Reading
- Arsenic in well water for dogs: the real screening level
- Is well water safe for dogs?
- Connecticut doesn't test your private well: two reasons you should
Sources: Connecticut groundwater arsenic records via U.S. Geological Survey and state monitoring (analyzed by CheckYourTap); U.S. EPA, National Primary Drinking Water Regulations; U.S. EPA, Private Drinking Water Wells. Dog screening levels are CheckYourTap estimates derived from the EPA human limit plus veterinary uncertainty factors, not official veterinary standards; confirm with your veterinarian. Town figures are counts from tested wells, not measurements of any individual home, and many readings are historical.