What was found in Wellesley'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 | 1447 µg/L 14% of the EPA limit 10000 µg/L Main supplier: WELLESLEY WATER DIVISION · 29,550 people · 2019
Highest in the city: 2800 µg/L — WELLESLEY COLLEGE · 3,000 people · 2019 | 2/2 | SYR4 |
| Fluoride | 972.5 µg/L 24% of the EPA limit 4000 µg/L Main supplier: WELLESLEY WATER DIVISION · 29,550 people · 2017 | 1/2 | SYR4 |
| Barium | 77.425 µg/L 3.9% of the EPA limit 2000 µg/L Main supplier: WELLESLEY WATER DIVISION · 29,550 people · 2017
Highest in the city: 159.49 µg/L — WELLESLEY COLLEGE · 3,000 people · 2016 | 2/2 | SYR4 |
| Copper | 105 µg/L 8.1% of the EPA limit 1300 µg/L Main supplier: WELLESLEY WATER DIVISION · 29,550 people · 2012 | 1/2 | SYR4 |
| TTHM | 47.44 µg/L 59% of the EPA limit 80 µg/L Main supplier: WELLESLEY WATER DIVISION · 29,550 people · 2019 | 2/2 | SYR4 |
| Total Haloacetic Acids (HAA5) | 14.19 µg/L 24% of the EPA limit 60 µg/L Main supplier: WELLESLEY WATER DIVISION · 29,550 people · 2019
Highest in the city: 24 µg/L — WELLESLEY COLLEGE · 3,000 people · 2019 | 2/2 | SYR4 |
| Dibromochloromethane | 16.84 µg/L No EPA limit set Main supplier: WELLESLEY WATER DIVISION · 29,550 people · 2019 | 1/2 | SYR4 |
| Bromodichloromethane | 16.6 µg/L No EPA limit set Main supplier: WELLESLEY WATER DIVISION · 29,550 people · 2019 | 1/2 | SYR4 |
| Chloroform | 13.16 µg/L No EPA limit set Main supplier: WELLESLEY WATER DIVISION · 29,550 people · 2019 | 1/2 | SYR4 |
| Cyanide | 8 µg/L 4% of the EPA limit 200 µg/L Highest in the city: WELLESLEY COLLEGE · 3,000 people · 2016 | 1/2 | SYR4 |
| Dichloroacetic Acid | 7.085 µg/L No EPA limit set Main supplier: WELLESLEY WATER DIVISION · 29,550 people · 2019 | 1/2 | SYR4 |
| Trichloroacetic Acid | 5.045 µg/L No EPA limit set Main supplier: WELLESLEY WATER DIVISION · 29,550 people · 2019 | 1/2 | SYR4 |
| Monobromoacetic Acid | 4.78 µg/L No EPA limit set Main supplier: WELLESLEY WATER DIVISION · 29,550 people · 2019 | 1/2 | SYR4 |
| Bromoform | 4.275 µg/L No EPA limit set Main supplier: WELLESLEY WATER DIVISION · 29,550 people · 2019 | 1/2 | SYR4 |
| Dibromoacetic Acid | 4.18 µg/L No EPA limit set Main supplier: WELLESLEY WATER DIVISION · 29,550 people · 2019 | 1/2 | SYR4 |
| Antimony, Total | 2.905 µg/L 48% of the EPA limit 6 µg/L Main supplier: WELLESLEY WATER DIVISION · 29,550 people · 2017 | 1/2 | SYR4 |
| Monochloroacetic Acid | 2.19 µg/L No EPA limit set Main supplier: WELLESLEY WATER DIVISION · 29,550 people · 2019 | 1/2 | SYR4 |
| Chromium | 1.4925 µg/L 1.5% of the EPA limit 100 µg/L Highest in the city: WELLESLEY COLLEGE · 3,000 people · 2016 | 1/2 | SYR4 |
| PFOS | 0.0066 µg/L No EPA limit set Main supplier: WELLESLEY WATER DIVISION · 29,550 people · 2025 | 1/2 | UCMR-5 |
| PFOA | 0.0063 µg/L No EPA limit set Main supplier: WELLESLEY WATER DIVISION · 29,550 people · 2025 | 1/2 | UCMR-5 |
| PFBS | 0.0053 µg/L No EPA limit set Main supplier: WELLESLEY WATER DIVISION · 29,550 people · 2025 | 1/2 | UCMR-5 |
| Pfba | 0.0052 µg/L No EPA limit set Main supplier: WELLESLEY WATER DIVISION · 29,550 people · 2025 | 1/2 | UCMR-5 |
| Lead | 0.0035 mg/L 23% of the EPA limit 0.0150 mg/L Main supplier: WELLESLEY WATER DIVISION · 29,550 people · 2025
Highest in the city: 0.0043 mg/L — WELLESLEY COLLEGE · 3,000 people · 2026 | 2/2 | LCR |
| Pfpea | 0.0043 µg/L No EPA limit set Main supplier: WELLESLEY WATER DIVISION · 29,550 people · 2025 | 1/2 | UCMR-5 |
| Pfhxa | 0.0039 µg/L No EPA limit set Main supplier: WELLESLEY WATER DIVISION · 29,550 people · 2025 | 1/2 | 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 Wellesley
| Supplier | Population served |
|---|---|
| WELLESLEY WATER DIVISION | 29,550 |
| WELLESLEY COLLEGE | 3,000 |
Frequently asked questions about Wellesley tap water
Is Wellesley tap water safe to drink?
EPA testing detected 25 contaminants in the water serving Wellesley. 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 Wellesley?
2 public water suppliers report drinking-water monitoring for Wellesley, Massachusetts to the EPA. Each is listed above with its population served.
What contaminants are in Wellesley's water?
The contaminants EPA monitoring detected in Wellesley include Nitrate, Fluoride, Barium, Copper, TTHM. 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.