What was found in Portsmouth'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 | 6950 µg/L 70% of the EPA limit 10000 µg/L Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2019 | 2/2 | SYR4 |
| Nitrate-Nitrite | 6780 µg/L 68% of the EPA limit 10000 µg/L Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2016 | 2/2 | SYR4 |
| Copper | 205.8 µg/L 16% of the EPA limit 1300 µg/L Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2019
Highest in the city: 663.75 µg/L — PEASE TRADE PORT · 9,900 people · 2019 | 2/2 | SYR4 |
| Fluoride | 554 µg/L 14% of the EPA limit 4000 µg/L Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2019 | 1/2 | SYR4 |
| TTHM | 98 µg/L 123% of the EPA limit, at the 95th percentile of samples — 80 µg/L Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2019 | 2/2 | SYR4 |
| Chloroform | 84.4 µg/L No EPA limit set Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2019 | 2/2 | SYR4 |
| Total Haloacetic Acids (HAA5) | 65.3 µg/L 109% of the EPA limit, at the 95th percentile of samples — 60 µg/L Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2019 | 2/2 | SYR4 |
| Lead | 46.9225 µg/L 313% of the EPA limit, at the 95th percentile of samples — 15 µg/L Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2019 | 2/2 | SYR4 |
| Trichloroacetic Acid | 40.5742 µg/L No EPA limit set Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2019 | 2/2 | SYR4 |
| Dichloroacetic Acid | 23 µg/L No EPA limit set Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2019 | 2/2 | SYR4 |
| Barium | 20.775 µg/L 1% of the EPA limit 2000 µg/L Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2019 | 2/2 | SYR4 |
| Bromodichloromethane | 13 µg/L No EPA limit set Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2019 | 2/2 | SYR4 |
| Lithium | 10 µg/L No EPA limit set Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2024 | 1/2 | UCMR-5 |
| Monochloroacetic Acid | 9.68415 µg/L No EPA limit set Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2019 | 2/2 | SYR4 |
| Chromium | 9.01 µg/L 9% of the EPA limit 100 µg/L Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2019 | 2/2 | SYR4 |
| Dibromochloromethane | 2.12 µg/L No EPA limit set Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2019 | 2/2 | SYR4 |
| Combined Radium (-226 And -228) | 1.998 pCi/L 40% of the EPA limit 5 pCi/L Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2018 | 2/2 | SYR4 |
| Combined Uranium | 1.525 µg/L 5.1% of the EPA limit 30 µg/L Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2019 | 1/2 | SYR4 |
| Arsenic | 1.495 µg/L 15% of the EPA limit 10 µg/L Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2019 | 1/2 | SYR4 |
| Gross Alpha, Excl. Radon And U | 1 pCi/L 6.7% of the EPA limit 15 pCi/L Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2018 | 1/2 | SYR4 |
| Bromoform | 0.7850 µg/L No EPA limit set Highest in the city: PEASE TRADE PORT · 9,900 people · 2019 | 1/2 | SYR4 |
| Pfba | 0.0050 µg/L No EPA limit set Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2024
Highest in the city: 0.0151 µg/L — PEASE TRADE PORT · 9,900 people · 2025 | 2/2 | UCMR-5 |
| PFBS | 0.0090 µg/L No EPA limit set Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2024 | 1/2 | UCMR-5 |
| PFOA | 0.0070 µg/L No EPA limit set Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2024 | 1/2 | UCMR-5 |
| Pfpea | 0.0070 µg/L No EPA limit set Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2024 | 1/2 | UCMR-5 |
| Pfhxa | 0.0060 µg/L No EPA limit set Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2024 | 1/2 | UCMR-5 |
| PFHXS | 0.0050 µg/L No EPA limit set Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2024 | 1/2 | UCMR-5 |
| PFOS | 0.0050 µg/L No EPA limit set Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2024 | 1/2 | UCMR-5 |
| Pfhpa | 0.0030 µg/L No EPA limit set Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2024 | 1/2 | UCMR-5 |
| Lead | 0.0 mg/L 0% of the EPA limit 0.0150 mg/L Main supplier: PORTSMOUTH WATER WORKS · 33,000 people · 2024 | 2/2 | 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 Portsmouth
| Supplier | Population served |
|---|---|
| PORTSMOUTH WATER WORKS | 33,000 |
| PEASE TRADE PORT | 9,900 |
Frequently asked questions about Portsmouth tap water
Is Portsmouth tap water safe to drink?
EPA testing detected 30 contaminants in the water serving Portsmouth. 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 Portsmouth?
2 public water suppliers report drinking-water monitoring for Portsmouth, New Hampshire to the EPA. Each is listed above with its population served.
What contaminants are in Portsmouth's water?
The contaminants EPA monitoring detected in Portsmouth include Nitrate, Nitrate-Nitrite, Copper, Fluoride, 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.