What was found in Groton'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 | 88 µg/L 0.9% of the EPA limit 10000 µg/L Main supplier: GROTON UTILITIES · 30,200 people · 2019
Highest in the city: 9100 µg/L — NEIGHBORS OF ROGERS, LLC · 57 people · 2019 | 4/7 | SYR4 |
| Nitrate-Nitrite | 93 µg/L 0.9% of the EPA limit 10000 µg/L Main supplier: GROTON UTILITIES · 30,200 people · 2019
Highest in the city: 8658.84 µg/L — NEIGHBORS OF ROGERS, LLC · 57 people · 2019 | 4/7 | SYR4 |
| Fluoride | 1038 µg/L 26% of the EPA limit 4000 µg/L Main supplier: GROTON UTILITIES · 30,200 people · 2019
Highest in the city: 1325 µg/L — MYSTIC VILLAGE APARTMENTS · 66 people · 2019 | 3/7 | SYR4 |
| Copper | 103 µg/L 7.9% of the EPA limit 1300 µg/L Main supplier: GROTON UTILITIES · 30,200 people · 2019
Highest in the city: 738.3 µg/L — NEIGHBORS OF ROGERS, LLC · 57 people · 2017 | 7/7 | SYR4 |
| Chlorite | 190 µg/L 19% of the EPA limit 1000 µg/L Main supplier: GROTON UTILITIES · 30,200 people · 2019 | 1/7 | SYR4 |
| TTHM | 88.86 µg/L 111% of the EPA limit, at the 95th percentile of samples — 80 µg/L Main supplier: GROTON UTILITIES · 30,200 people · 2019
Highest in the city: 94.02 µg/L — LEDYARD WPCA, GALES FERRY SYSTEM · 2,369 people · 2019 | 5/7 | SYR4 |
| Barium | 14.75 µg/L 0.7% of the EPA limit 2000 µg/L Main supplier: GROTON UTILITIES · 30,200 people · 2019
Highest in the city: 83.4 µg/L — NEIGHBORS OF ROGERS, LLC · 57 people · 2016 | 4/7 | SYR4 |
| Chloroform | 15.715 µg/L No EPA limit set Main supplier: GROTON UTILITIES · 30,200 people · 2019
Highest in the city: 67 µg/L — AQUARION-MYSTIC · 10,788 people · 2019 | 3/7 | SYR4 |
| Total Haloacetic Acids (HAA5) | 36.31 µg/L 61% of the EPA limit 60 µg/L Main supplier: GROTON UTILITIES · 30,200 people · 2019
Highest in the city: 67 µg/L — AQUARION-MYSTIC · 10,788 people · 2019 | 5/7 | SYR4 |
| Lead | 54.8 µg/L 365% of the EPA limit, at the 95th percentile of samples — 15 µg/L Main supplier: GROTON UTILITIES · 30,200 people · 2019 | 7/7 | SYR4 |
| Trichloroacetic Acid | 36 µg/L No EPA limit set Highest in the city: AQUARION-MYSTIC · 10,788 people · 2019 | 1/7 | SYR4 |
| Dichloroacetic Acid | 27 µg/L No EPA limit set Highest in the city: AQUARION-MYSTIC · 10,788 people · 2019 | 1/7 | SYR4 |
| Bromodichloromethane | 7.615 µg/L No EPA limit set Main supplier: GROTON UTILITIES · 30,200 people · 2019
Highest in the city: 17 µg/L — AQUARION-MYSTIC · 10,788 people · 2019 | 2/7 | SYR4 |
| Combined Uranium | 12.44 µg/L 41% of the EPA limit 30 µg/L Highest in the city: MYSTIC VILLAGE APARTMENTS · 66 people · 2019 | 2/7 | SYR4 |
| Gross Alpha, Excl. Radon And U | 6.618 pCi/L 44% of the EPA limit 15 pCi/L Highest in the city: MYSTIC VILLAGE APARTMENTS · 66 people · 2019 | 2/7 | SYR4 |
| Nitrite | 6.5 µg/L 0.7% of the EPA limit 1000 µg/L Highest in the city: MYSTIC VILLAGE APARTMENTS · 66 people · 2019 | 1/7 | SYR4 |
| Dibromochloromethane | 1.965 µg/L No EPA limit set Main supplier: GROTON UTILITIES · 30,200 people · 2019
Highest in the city: 4 µg/L — AQUARION-MYSTIC · 10,788 people · 2019 | 2/7 | SYR4 |
| Di(2-ethylhexyl) Phthalate | 3.7 µg/L 62% of the EPA limit 6 µg/L Highest in the city: MYSTIC VILLAGE APARTMENTS · 66 people · 2019 | 2/7 | SYR4 |
| Monochloroacetic Acid | 3 µg/L No EPA limit set Highest in the city: AQUARION-MYSTIC · 10,788 people · 2019 | 1/7 | SYR4 |
| Combined Radium (-226 And -228) | 2.7885 pCi/L 56% of the EPA limit 5 pCi/L Highest in the city: NEIGHBORS OF ROGERS, LLC · 57 people · 2019 | 2/7 | SYR4 |
| Cadmium | 1 µg/L 20% of the EPA limit 5 µg/L Highest in the city: AQUARION-MYSTIC · 10,788 people · 2019 | 1/7 | SYR4 |
| Dibromoacetic Acid | 1 µg/L No EPA limit set Highest in the city: AQUARION-MYSTIC · 10,788 people · 2019 | 1/7 | SYR4 |
| Monobromoacetic Acid | 1 µg/L No EPA limit set Highest in the city: AQUARION-MYSTIC · 10,788 people · 2019 | 1/7 | SYR4 |
| Thallium, Total | 1 µg/L 50% of the EPA limit 2 µg/L Highest in the city: MYSTIC VILLAGE APARTMENTS · 66 people · 2019 | 1/7 | SYR4 |
| Bromoform | 0.8900 µg/L No EPA limit set Highest in the city: MYSTIC VILLAGE APARTMENTS · 66 people · 2017 | 1/7 | SYR4 |
| PFBS | 0.0040 µg/L No EPA limit set Highest in the city: AQUARION-MYSTIC · 10,788 people · 2025 | 1/7 | UCMR-5 |
| Lead | 0.0 mg/L 0% of the EPA limit 0.0150 mg/L Main supplier: GROTON UTILITIES · 30,200 people · 2025
Highest in the city: 0.0024 mg/L — NEIGHBORS OF ROGERS, LLC · 57 people · 2023 | 7/7 | LCR |
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 Groton
| Supplier | Population served |
|---|---|
| GROTON UTILITIES | 30,200 |
| AQUARION-MYSTIC | 10,788 |
| GROTON LONG POINT ASSOCIATION | 2,400 |
| LEDYARD WPCA, GALES FERRY SYSTEM | 2,369 |
| NOANK FIRE DISTRICT | 1,947 |
| MYSTIC VILLAGE APARTMENTS | 66 |
| NEIGHBORS OF ROGERS, LLC | 57 |
Frequently asked questions about Groton tap water
Is Groton tap water safe to drink?
EPA testing detected 27 contaminants in the water serving Groton. 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 Groton?
7 public water suppliers report drinking-water monitoring for Groton, Connecticut to the EPA. Each is listed above with its population served.
What contaminants are in Groton's water?
The contaminants EPA monitoring detected in Groton include Nitrate, Nitrate-Nitrite, Fluoride, Copper, Chlorite. 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.