Ctwc - Thompson System, CT
Lead detected, under the action levels
Latest 90th-percentile lead: 1.1 ppb (monitoring period 2025-2025). The federal action level is 15 ppb today and drops to 10 ppb in Nov 2027; EPA's health goal is 0. Lead was measured in sampled homes but the 90th percentile is under both action levels. EPA's health goal for lead is zero, so test your own tap if your home was built before 1986 or anyone in it is pregnant or a young child.
About Ctwc - Thompson System
Ctwc - Thompson System serves about 1,070 people through 484 service connections, which makes it a small system under EPA's size classes. It is privately owned and draws groundwater, in Windham County, Connecticut. EPA system ID: CT1410011; phone on file: 860-944-9655. Call that number and ask whether your address has a lead, galvanized or unknown service line.
Lead results over time
Against the period ending 2024 (0.6 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Ctwc - Thompson System is 3.2 ppb across 10 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 1.1 ppb |
| 2024 | 0.6 ppb |
| 2023 | 1 ppb |
| 2022 | 1.8 ppb |
| 2021 | 1 ppb |
| 2020 | 0 (not detected) |
| 2019 | 1 ppb |
| 2018 | 2 ppb |
| 2017 | 3.2 ppb |
| 2016 | 2 ppb |
How Ctwc - Thompson System compares
Of the 493 Connecticut systems with a lead result, the median latest reading is 0.8 ppb; 2 are over 15 ppb right now and 49 have gone over at some point. Ctwc - Thompson System's 1.1 ppb sits at the 59th percentile in Connecticut and the 57th nationally (higher means more lead).
Other water systems in Windham County
45 other systems share Windham County; 17 of them have a higher latest lead result than Ctwc - Thompson System. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Windham Water Works | 21,214 | 0 (not detected) |
| Putnam Water Pollution Control Authority | 7,300 | 0 (not detected) |
| Ctwc - Crystal System | 6,378 | 2.1 ppb |
| Ctwc - Gallup System | 2,538 | 2.3 ppb |
| Ctwc - Plainfield System | 1,713 | 0 (not detected) |
| Woodstock Academy South Campus | 620 | 7.9 ppb |
| Pomfret School | 400 | 0 (not detected) |
| Ctwc - Ashford Park Division | 334 | 0 (not detected) |
| Wyndham Park Apartments | 312 | 1.4 ppb |
| Sterling Water System | 308 | 0.8 ppb |
Next steps for Clinton, CT
Test your own tap with a certified lab first-draw sample; Clinton, CT may offer free or low-cost kits through the utility. If your own line is lead, replacing the private side runs about $1,200-$12,300 (EPA average about $4,700). Ask Ctwc - Thompson System whether it covers that cost before hiring anyone - many utilities now do.
These figures describe homes the utility sampled, not your tap. Only your service line record or a test of your own water answers the question for your house. The lead result guide covers how utilities pick the homes they sample. Systems that went over once often dip back under; here is what that means.