What was found in Marlborough'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 |
|---|---|---|---|
| Fluoride | 293 µg/L 7.3% of the EPA limit 4000 µg/L Main supplier: AQUARION-MARLBOROUGH · 1,348 people · 2018
Highest in the city: 2200 µg/L — LAUREL HILL WATER ASSOCIATION · 86 people · 2018 | 6/7 | SYR4 |
| Nitrate | 960 µg/L 9.6% of the EPA limit 10000 µg/L Main supplier: AQUARION-MARLBOROUGH · 1,348 people · 2019
Highest in the city: 1460 µg/L — CTWC - MARLBOROUGH GARDENS · 110 people · 2019 | 5/7 | SYR4 |
| Nitrate-Nitrite | 855 µg/L 8.6% of the EPA limit 10000 µg/L Main supplier: AQUARION-MARLBOROUGH · 1,348 people · 2019
Highest in the city: 1316 µg/L — CTWC - MARLBOROUGH GARDENS · 110 people · 2019 | 5/7 | SYR4 |
| Copper | 386.65 µg/L 30% of the EPA limit 1300 µg/L Main supplier: AQUARION-MARLBOROUGH · 1,348 people · 2019
Highest in the city: 1154.5 µg/L — CTWC - MARLBOROUGH GARDENS · 110 people · 2018 | 7/7 | SYR4 |
| Barium | 4.8 µg/L 0.2% of the EPA limit 2000 µg/L Main supplier: AQUARION-MARLBOROUGH · 1,348 people · 2018
Highest in the city: 131.88 µg/L — MARLBOROUGH HEALTH CARE CENTER, INC · 165 people · 2018 | 4/7 | SYR4 |
| Lead | 7 µg/L 47% of the EPA limit 15 µg/L Main supplier: AQUARION-MARLBOROUGH · 1,348 people · 2019
Highest in the city: 93 µg/L — MARLBOROUGH HEALTH CARE CENTER, INC · 165 people · 2019 | 7/7 | SYR4 |
| Total Haloacetic Acids (HAA5) | 29.18 µg/L 49% of the EPA limit 60 µg/L Highest in the city: MARLBOROUGH HEALTH CARE CENTER, INC · 165 people · 2019 | 2/7 | SYR4 |
| TTHM | 23.05 µg/L 29% of the EPA limit 80 µg/L Highest in the city: CTWC - FOREST HOMES DIVISION · 100 people · 2019 | 2/7 | SYR4 |
| Gross Alpha, Excl. Radon And U | 23.036 pCi/L 154% of the EPA limit, at the 95th percentile of samples — 15 pCi/L Highest in the city: MARLBOROUGH HEALTH CARE CENTER, INC · 165 people · 2019 | 2/7 | SYR4 |
| Monobromoacetic Acid | 18.16 µg/L No EPA limit set Highest in the city: MARLBOROUGH HEALTH CARE CENTER, INC · 165 people · 2019 | 1/7 | SYR4 |
| Dibromochloromethane | 8.31 µg/L No EPA limit set Highest in the city: CTWC - FOREST HOMES DIVISION · 100 people · 2019 | 2/7 | SYR4 |
| Bromodichloromethane | 7.51 µg/L No EPA limit set Highest in the city: CTWC - FOREST HOMES DIVISION · 100 people · 2019 | 2/7 | SYR4 |
| Combined Radium (-226 And -228) | 6.36 pCi/L 127% of the EPA limit, at the 95th percentile of samples — 5 pCi/L Highest in the city: MARLBOROUGH HEALTH CARE CENTER, INC · 165 people · 2019 | 1/7 | SYR4 |
| Combined Uranium | 4.2 µg/L 14% of the EPA limit 30 µg/L Highest in the city: CTWC - SACHEM VILLAGE CONDO · 166 people · 2013 | 2/7 | SYR4 |
| Dichloroacetic Acid | 3.83 µg/L No EPA limit set Highest in the city: MARLBOROUGH HEALTH CARE CENTER, INC · 165 people · 2019 | 2/7 | SYR4 |
| Bromoform | 3.685 µg/L No EPA limit set Highest in the city: CTWC - FOREST HOMES DIVISION · 100 people · 2019 | 1/7 | SYR4 |
| Dibromoacetic Acid | 3.375 µg/L No EPA limit set Highest in the city: MARLBOROUGH HEALTH CARE CENTER, INC · 165 people · 2019 | 2/7 | SYR4 |
| Chloroform | 3.26 µg/L No EPA limit set Highest in the city: CTWC - FOREST HOMES DIVISION · 100 people · 2019 | 2/7 | SYR4 |
| Trichloroacetic Acid | 2.16 µg/L No EPA limit set Highest in the city: MARLBOROUGH HEALTH CARE CENTER, INC · 165 people · 2019 | 1/7 | SYR4 |
| Arsenic | 1.5 µg/L 15% of the EPA limit 10 µg/L Highest in the city: LAUREL HILL WATER ASSOCIATION · 86 people · 2018 | 1/7 | SYR4 |
| Chromium | 1.1 µg/L 1.1% of the EPA limit 100 µg/L Highest in the city: LAUREL HILL WATER ASSOCIATION · 86 people · 2018 | 2/7 | SYR4 |
| Monochloroacetic Acid | 0.7000 µg/L No EPA limit set Highest in the city: MARLBOROUGH HEALTH CARE CENTER, INC · 165 people · 2019 | 1/7 | SYR4 |
| Antimony, Total | 0.5000 µg/L 8.3% of the EPA limit 6 µg/L Highest in the city: MARLBOROUGH HEALTH CARE CENTER, INC · 165 people · 2018 | 1/7 | SYR4 |
| Lead | 0.0 mg/L 0% of the EPA limit 0.0150 mg/L Main supplier: AQUARION-MARLBOROUGH · 1,348 people · 2025
Highest in the city: 0.0023 mg/L — LAUREL HILL WATER ASSOCIATION · 86 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 Marlborough
| Supplier | Population served |
|---|---|
| AQUARION-MARLBOROUGH | 1,348 |
| CTWC - SACHEM VILLAGE CONDO | 166 |
| MARLBOROUGH HEALTH CARE CENTER, INC | 165 |
| CTWC - MARLBOROUGH GARDENS | 110 |
| CTWC - FOREST HOMES DIVISION | 100 |
| LAUREL HILL WATER ASSOCIATION | 86 |
| CTWC - FLORENCE LORD (MASH) | 30 |
Frequently asked questions about Marlborough tap water
Is Marlborough tap water safe to drink?
EPA testing detected 24 contaminants in the water serving Marlborough. 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 Marlborough?
7 public water suppliers report drinking-water monitoring for Marlborough, Connecticut to the EPA. Each is listed above with its population served.
What contaminants are in Marlborough's water?
The contaminants EPA monitoring detected in Marlborough include Fluoride, Nitrate, Nitrate-Nitrite, Copper, 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.