What was found in Colchester's water
The level at the city's main supplier, the highest level anywhere in the city, the EPA limit for each, and where every figure comes from.
| Contaminant | Level vs EPA limit | Suppliers | Source |
|---|---|---|---|
| Nitrate | 2070 µg/L 21% of the EPA limit 10000 µg/L Main supplier: COLCHESTER SEWER & WATER COMMISSION · 4,020 people · 2019 | 8/8 | SYR4 |
| Nitrate-Nitrite | 1990 µg/L 20% of the EPA limit 10000 µg/L Main supplier: COLCHESTER SEWER & WATER COMMISSION · 4,020 people · 2019 | 8/8 | SYR4 |
| Fluoride | 60 µg/L 1.5% of the EPA limit 4000 µg/L Main supplier: COLCHESTER SEWER & WATER COMMISSION · 4,020 people · 2018
Highest in the city: 1290.5 µg/L — COLCHESTER COMMONS · 224 people · 2019 | 8/8 | SYR4 |
| TTHM | 29.355 µg/L 37% of the EPA limit 80 µg/L Main supplier: COLCHESTER SEWER & WATER COMMISSION · 4,020 people · 2019
Highest in the city: 769.065 µg/L — COLCHESTER ESTATES · 276 people · 2019 | 4/8 | SYR4 |
| Copper | 171.8 µg/L 13% of the EPA limit 1300 µg/L Main supplier: COLCHESTER SEWER & WATER COMMISSION · 4,020 people · 2019
Highest in the city: 425.8 µg/L — COLCHESTER COMMONS · 224 people · 2019 | 8/8 | SYR4 |
| Bromodichloromethane | 7.185 µg/L No EPA limit set Main supplier: COLCHESTER SEWER & WATER COMMISSION · 4,020 people · 2019
Highest in the city: 354.8 µg/L — COLCHESTER ESTATES · 276 people · 2019 | 4/8 | SYR4 |
| Dibromochloromethane | 4.095 µg/L No EPA limit set Main supplier: COLCHESTER SEWER & WATER COMMISSION · 4,020 people · 2019
Highest in the city: 325.31 µg/L — COLCHESTER ESTATES · 276 people · 2019 | 4/8 | SYR4 |
| Lead | 14.2 µg/L 95% of the EPA limit 15 µg/L Main supplier: COLCHESTER SEWER & WATER COMMISSION · 4,020 people · 2019
Highest in the city: 89.27 µg/L — WESTCHESTER HILLS CONDOMINIUM ASSN. · 225 people · 2019 | 8/8 | SYR4 |
| Barium | 25.5 µg/L 1.3% of the EPA limit 2000 µg/L Main supplier: COLCHESTER SEWER & WATER COMMISSION · 4,020 people · 2018 | 8/8 | SYR4 |
| Total Haloacetic Acids (HAA5) | 12.3 µg/L 21% of the EPA limit 60 µg/L Main supplier: COLCHESTER SEWER & WATER COMMISSION · 4,020 people · 2019
Highest in the city: 22.15 µg/L — COLCHESTER ESTATES · 276 people · 2019 | 4/8 | SYR4 |
| Monobromoacetic Acid | 1 µg/L No EPA limit set Main supplier: COLCHESTER SEWER & WATER COMMISSION · 4,020 people · 2019
Highest in the city: 20.34 µg/L — COLCHESTER ESTATES · 276 people · 2019 | 2/8 | SYR4 |
| Chloroform | 18.85 µg/L No EPA limit set Main supplier: COLCHESTER SEWER & WATER COMMISSION · 4,020 people · 2019 | 4/8 | SYR4 |
| Nitrite | 10 µg/L 1% of the EPA limit 1000 µg/L Highest in the city: KNOB HILL CONDOMINIUMS · 84 people · 2019 | 1/8 | SYR4 |
| Combined Uranium | 9.407 µg/L 31% of the EPA limit 30 µg/L Highest in the city: COLCHESTER COMMONS · 224 people · 2019 | 2/8 | SYR4 |
| Dichloroacetic Acid | 6.98 µg/L No EPA limit set Main supplier: COLCHESTER SEWER & WATER COMMISSION · 4,020 people · 2019 | 4/8 | SYR4 |
| Gross Alpha, Excl. Radon And U | 6.971 pCi/L 46% of the EPA limit 15 pCi/L Main supplier: COLCHESTER SEWER & WATER COMMISSION · 4,020 people · 2018 | 4/8 | SYR4 |
| Combined Radium (-226 And -228) | 1.086 pCi/L 22% of the EPA limit 5 pCi/L Main supplier: COLCHESTER SEWER & WATER COMMISSION · 4,020 people · 2018
Highest in the city: 6.8 pCi/L — COLCHESTER COMMONS · 224 people · 2019 | 4/8 | SYR4 |
| Selenium | 6 µg/L 12% of the EPA limit 50 µg/L Main supplier: COLCHESTER SEWER & WATER COMMISSION · 4,020 people · 2018 | 1/8 | SYR4 |
| Trichloroacetic Acid | 3.905 µg/L No EPA limit set Main supplier: COLCHESTER SEWER & WATER COMMISSION · 4,020 people · 2019 | 2/8 | SYR4 |
| Arsenic | 3 µg/L 30% of the EPA limit 10 µg/L Highest in the city: COLCHESTER COMMONS · 224 people · 2019 | 1/8 | SYR4 |
| Di(2-ethylhexyl) Phthalate | 2.62 µg/L 44% of the EPA limit 6 µg/L Highest in the city: KNOB HILL CONDOMINIUMS · 84 people · 2019 | 2/8 | SYR4 |
| Chromium | 1.95 µg/L 2% of the EPA limit 100 µg/L Highest in the city: KNOB HILL CONDOMINIUMS · 84 people · 2018 | 3/8 | SYR4 |
| Dibromoacetic Acid | 1.83 µg/L No EPA limit set Main supplier: COLCHESTER SEWER & WATER COMMISSION · 4,020 people · 2019 | 3/8 | SYR4 |
| Bromoform | 0.7000 µg/L No EPA limit set Main supplier: COLCHESTER SEWER & WATER COMMISSION · 4,020 people · 2019
Highest in the city: 1.3 µg/L — CTWC - AMSTON LAKE DIVISION · 910 people · 2019 | 3/8 | SYR4 |
| Monochloroacetic Acid | 1 µg/L No EPA limit set Main supplier: COLCHESTER SEWER & WATER COMMISSION · 4,020 people · 2019 | 1/8 | SYR4 |
| Tetrachloroethylene | 0.7640 µg/L 15% of the EPA limit 5 µg/L Main supplier: COLCHESTER SEWER & WATER COMMISSION · 4,020 people · 2019 | 1/8 | SYR4 |
| Toluene | 0.6300 µg/L 0.1% of the EPA limit 1000 µg/L Highest in the city: COLCHESTER COMMONS · 224 people · 2019 | 1/8 | SYR4 |
| Benzo(A)Pyrene | 0.1600 µg/L 80% of the EPA limit 0.2000 µg/L Highest in the city: COLCHESTER COMMONS · 224 people · 2019 | 1/8 | SYR4 |
| Simazine | 0.0500 µg/L 1.3% of the EPA limit 4 µg/L Main supplier: COLCHESTER SEWER & WATER COMMISSION · 4,020 people · 2019 | 1/8 | SYR4 |
| PFOS | 0.0090 µg/L No EPA limit set Main supplier: COLCHESTER SEWER & WATER COMMISSION · 4,020 people · 2023 | 1/8 | UCMR-5 |
| Lead | 0.0 mg/L 0% of the EPA limit 0.0150 mg/L Main supplier: COLCHESTER SEWER & WATER COMMISSION · 4,020 people · 2025
Highest in the city: 0.0047 mg/L — CTWC - PONEMAH VILLAGE · 60 people · 2024 | 8/8 | LCR |
| PFHXS | 0.0036 µg/L No EPA limit set Main supplier: COLCHESTER SEWER & WATER COMMISSION · 4,020 people · 2023 | 1/8 | UCMR-5 |
Each bar shows the measured level as a share of the EPA limit: green is
well under, amber is close to it, red is over. For lead and copper the
limit applies to exactly the 90th-percentile figure shown, so red there
means a real exceedance. For everything else the limit applies to a
running annual average while the figure is the 95th percentile of the
system's samples — over 100% is worth reading, but is not by itself a
violation.
Formal violations are listed separately.
These are the utilities' own EPA-reported results, not a city-wide
average. A detection means the lab measured the
substance — it isn't the same as exceeding a legal limit. Hover a source
tag to see the EPA program and years behind each figure.
Water suppliers serving Colchester
| Supplier | Population served |
|---|---|
| COLCHESTER SEWER & WATER COMMISSION | 4,020 |
| CTWC - AMSTON LAKE DIVISION | 910 |
| COLCHESTER ESTATES | 276 |
| CTWC - WESTCHESTER VILLAGE | 252 |
| WESTCHESTER HILLS CONDOMINIUM ASSN. | 225 |
| COLCHESTER COMMONS | 224 |
| KNOB HILL CONDOMINIUMS | 84 |
| CTWC - PONEMAH VILLAGE | 60 |
Frequently asked questions about Colchester tap water
Is Colchester tap water safe to drink?
EPA testing detected 32 contaminants in the water serving Colchester. A detection isn't the same as a violation — most detected levels are within federal limits. Check the level and source for each contaminant above, and your utility's annual Consumer Confidence Report for the official compliance status.
How many water suppliers serve Colchester?
8 public water suppliers report drinking-water monitoring for Colchester, Connecticut to the EPA. Each is listed above with its population served.
What contaminants are in Colchester's water?
The contaminants EPA monitoring detected in Colchester include Nitrate, Nitrate-Nitrite, Fluoride, TTHM, Copper. The full list, with the level at the main supplier and the data source, is in the table above.
Where does this data come from?
Every figure is official EPA drinking-water monitoring — the Lead & Copper Rule, the UCMR-5 nationwide testing program, and the EPA Six-Year Review — not our own testing. Each number is labelled with its source and period.