What was found in North Stonington'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-Nitrite | 628 µg/L 6.3% of the EPA limit 10000 µg/L Main supplier: SCWA, NORTH STONINGTON DIVISION (NST) · 1,860 people · 2019
Highest in the city: 5337.5 µg/L — SCWA, CEDAR RIDGE DIVISION · 370 people · 2019 | 3/3 | SYR4 |
| Nitrate | 640 µg/L 6.4% of the EPA limit 10000 µg/L Main supplier: SCWA, NORTH STONINGTON DIVISION (NST) · 1,860 people · 2019
Highest in the city: 4442 µg/L — SCWA, CEDAR RIDGE DIVISION · 370 people · 2019 | 3/3 | SYR4 |
| Copper | 633.4 µg/L 49% of the EPA limit 1300 µg/L Main supplier: SCWA, NORTH STONINGTON DIVISION (NST) · 1,860 people · 2018
Highest in the city: 968.8 µg/L — SCWA, CEDAR RIDGE DIVISION · 370 people · 2019 | 3/3 | SYR4 |
| Fluoride | 524 µg/L 13% of the EPA limit 4000 µg/L Highest in the city: NORTHSTONE GARDENS · 79 people · 2019 | 1/3 | SYR4 |
| Barium | 9.9 µg/L 0.5% of the EPA limit 2000 µg/L Main supplier: SCWA, NORTH STONINGTON DIVISION (NST) · 1,860 people · 2018
Highest in the city: 133.7 µg/L — NORTHSTONE GARDENS · 79 people · 2019 | 3/3 | SYR4 |
| Nitrite | 93 µg/L 9.3% of the EPA limit 1000 µg/L Highest in the city: NORTHSTONE GARDENS · 79 people · 2019 | 1/3 | SYR4 |
| Combined Uranium | 12.3 µg/L 41% of the EPA limit 30 µg/L Highest in the city: SCWA, CEDAR RIDGE DIVISION · 370 people · 2019 | 2/3 | SYR4 |
| TTHM | 11.26 µg/L 14% of the EPA limit 80 µg/L Highest in the city: SCWA, CEDAR RIDGE DIVISION · 370 people · 2019 | 1/3 | SYR4 |
| Gross Alpha, Excl. Radon And U | 6.38 pCi/L 43% of the EPA limit 15 pCi/L Main supplier: SCWA, NORTH STONINGTON DIVISION (NST) · 1,860 people · 2019
Highest in the city: 6.97 pCi/L — NORTHSTONE GARDENS · 79 people · 2019 | 3/3 | SYR4 |
| Lead | 6.5 µg/L 43% of the EPA limit 15 µg/L Main supplier: SCWA, NORTH STONINGTON DIVISION (NST) · 1,860 people · 2018 | 2/3 | SYR4 |
| Combined Radium (-226 And -228) | 4.53 pCi/L 91% of the EPA limit 5 pCi/L Highest in the city: SCWA, CEDAR RIDGE DIVISION · 370 people · 2019 | 2/3 | SYR4 |
| Chloroform | 3.915 µg/L No EPA limit set Highest in the city: SCWA, CEDAR RIDGE DIVISION · 370 people · 2019 | 1/3 | SYR4 |
| Total Haloacetic Acids (HAA5) | 3.845 µg/L 6.4% of the EPA limit 60 µg/L Highest in the city: SCWA, CEDAR RIDGE DIVISION · 370 people · 2019 | 1/3 | SYR4 |
| Bromodichloromethane | 3.09 µg/L No EPA limit set Highest in the city: SCWA, CEDAR RIDGE DIVISION · 370 people · 2019 | 1/3 | SYR4 |
| Dibromochloromethane | 2.94 µg/L No EPA limit set Highest in the city: SCWA, CEDAR RIDGE DIVISION · 370 people · 2019 | 1/3 | SYR4 |
| Dichloroacetic Acid | 2.15 µg/L No EPA limit set Highest in the city: SCWA, CEDAR RIDGE DIVISION · 370 people · 2019 | 1/3 | SYR4 |
| Dibromoacetic Acid | 1.73 µg/L No EPA limit set Highest in the city: SCWA, CEDAR RIDGE DIVISION · 370 people · 2019 | 1/3 | SYR4 |
| Chromium | 1.3 µg/L 1.3% of the EPA limit 100 µg/L Highest in the city: NORTHSTONE GARDENS · 79 people · 2019 | 1/3 | SYR4 |
| Bromoform | 0.8600 µg/L No EPA limit set Highest in the city: SCWA, CEDAR RIDGE DIVISION · 370 people · 2019 | 1/3 | SYR4 |
| Beryllium, Total | 0.2000 µg/L 5% of the EPA limit 4 µg/L Main supplier: SCWA, NORTH STONINGTON DIVISION (NST) · 1,860 people · 2018 | 2/3 | SYR4 |
| Lead | 0.0019 mg/L 13% of the EPA limit 0.0150 mg/L Main supplier: SCWA, NORTH STONINGTON DIVISION (NST) · 1,860 people · 2025
Highest in the city: 0.0023 mg/L — NORTHSTONE GARDENS · 79 people · 2025 | 3/3 | 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 North Stonington
| Supplier | Population served |
|---|---|
| SCWA, NORTH STONINGTON DIVISION (NST) | 1,860 |
| SCWA, CEDAR RIDGE DIVISION | 370 |
| NORTHSTONE GARDENS | 79 |
Frequently asked questions about North Stonington tap water
Is North Stonington tap water safe to drink?
EPA testing detected 21 contaminants in the water serving North Stonington. 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 North Stonington?
3 public water suppliers report drinking-water monitoring for North Stonington, Connecticut to the EPA. Each is listed above with its population served.
What contaminants are in North Stonington's water?
The contaminants EPA monitoring detected in North Stonington include Nitrate-Nitrite, Nitrate, Copper, Fluoride, Barium. 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.