What was found in Washington'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 | 2000 µg/L 20% of the EPA limit 10000 µg/L Highest in the city: WASHINGTON AQUEDUCT DIVISION. · 0 people · 2017 | 1/3 | SYR4 |
| Nitrate-Nitrite | 1989.9999999999998 µg/L 20% of the EPA limit 10000 µg/L Highest in the city: WASHINGTON AQUEDUCT DIVISION. · 0 people · 2017 | 1/3 | SYR4 |
| Fluoride | 842.5 µg/L 21% of the EPA limit 4000 µg/L Highest in the city: WASHINGTON AQUEDUCT DIVISION. · 0 people · 2017 | 1/3 | SYR4 |
| TTHM | 75.39999999999998 µg/L 94% of the EPA limit 80 µg/L Main supplier: D.C. WATER AND SEWER AUTHORITY · 632,323 people · 2017
Highest in the city: 78.94999999999999 µg/L — JOINT BASE ANACOSTIA - BOLLING · 19,312 people · 2017 | 3/3 | SYR4 |
| Chloroform | 47.95 µg/L No EPA limit set Main supplier: D.C. WATER AND SEWER AUTHORITY · 632,323 people · 2016 | 2/3 | SYR4 |
| Total Haloacetic Acids (HAA5) | 44.48 µg/L 74% of the EPA limit 60 µg/L Main supplier: D.C. WATER AND SEWER AUTHORITY · 632,323 people · 2017
Highest in the city: 47.63 µg/L — JOINT BASE ANACOSTIA - BOLLING · 19,312 people · 2017 | 3/3 | SYR4 |
| Barium | 41.5 µg/L 2.1% of the EPA limit 2000 µg/L Highest in the city: WASHINGTON AQUEDUCT DIVISION. · 0 people · 2017 | 1/3 | SYR4 |
| Dichloroacetic Acid | 26.6 µg/L No EPA limit set Highest in the city: JOINT BASE ANACOSTIA - BOLLING · 19,312 people · 2016 | 1/3 | SYR4 |
| Bromodichloromethane | 20.99 µg/L No EPA limit set Main supplier: D.C. WATER AND SEWER AUTHORITY · 632,323 people · 2016 | 2/3 | SYR4 |
| Trichloroacetic Acid | 15.1 µg/L No EPA limit set Highest in the city: JOINT BASE ANACOSTIA - BOLLING · 19,312 people · 2016 | 1/3 | SYR4 |
| Monobromoacetic Acid | 8.1 µg/L No EPA limit set Main supplier: D.C. WATER AND SEWER AUTHORITY · 632,323 people · 2016 | 1/3 | SYR4 |
| Copper | 7.699999999999999 µg/L 0.6% of the EPA limit 1300 µg/L Highest in the city: WASHINGTON AQUEDUCT DIVISION. · 0 people · 2016 | 1/3 | SYR4 |
| Dibromochloromethane | 5.765 µg/L No EPA limit set Main supplier: D.C. WATER AND SEWER AUTHORITY · 632,323 people · 2016
Highest in the city: 6.2 µg/L — JOINT BASE ANACOSTIA - BOLLING · 19,312 people · 2016 | 2/3 | SYR4 |
| Monochloroacetic Acid | 3.5 µg/L No EPA limit set Highest in the city: JOINT BASE ANACOSTIA - BOLLING · 19,312 people · 2016 | 1/3 | SYR4 |
| Dibromoacetic Acid | 2.5 µg/L No EPA limit set Main supplier: D.C. WATER AND SEWER AUTHORITY · 632,323 people · 2016 | 2/3 | SYR4 |
| Gross Beta Particle Activity | 1.597 pCi/L No EPA limit set Highest in the city: WASHINGTON AQUEDUCT DIVISION. · 0 people · 2017 | 1/3 | SYR4 |
| Dalapon | 1.3 µg/L 0.7% of the EPA limit 200 µg/L Highest in the city: WASHINGTON AQUEDUCT DIVISION. · 0 people · 2017 | 1/3 | SYR4 |
| Combined Radium (-226 And -228) | 0.4072 pCi/L 8.1% of the EPA limit 5 pCi/L Highest in the city: WASHINGTON AQUEDUCT DIVISION. · 0 people · 2017 | 1/3 | SYR4 |
| Arsenic | 0.3800 µg/L 3.8% of the EPA limit 10 µg/L Highest in the city: WASHINGTON AQUEDUCT DIVISION. · 0 people · 2017 | 1/3 | SYR4 |
| Gross Alpha, Excl. Radon And U | 0.2190 pCi/L 1.5% of the EPA limit 15 pCi/L Highest in the city: WASHINGTON AQUEDUCT DIVISION. · 0 people · 2017 | 1/3 | SYR4 |
| Antimony, Total | 0.2000 µg/L 3.3% of the EPA limit 6 µg/L Highest in the city: WASHINGTON AQUEDUCT DIVISION. · 0 people · 2017 | 1/3 | SYR4 |
| Atrazine | 0.1502 µg/L 5% of the EPA limit 3 µg/L Highest in the city: WASHINGTON AQUEDUCT DIVISION. · 0 people · 2017 | 1/3 | SYR4 |
| Simazine | 0.0700 µg/L 1.8% of the EPA limit 4 µg/L Highest in the city: WASHINGTON AQUEDUCT DIVISION. · 0 people · 2017 | 1/3 | SYR4 |
| Lead | 0.0020 mg/L 13% of the EPA limit 0.0150 mg/L Main supplier: D.C. WATER AND SEWER AUTHORITY · 632,323 people · 2025
Highest in the city: 0.0390 mg/L — WASHINGTON AQUEDUCT DIVISION. · 0 people · 1992 | 3/3 | LCR |
| Pfpea | 0.0047 µg/L No EPA limit set Main supplier: D.C. WATER AND SEWER AUTHORITY · 632,323 people · 2024
Highest in the city: 0.0056 µg/L — JOINT BASE ANACOSTIA - BOLLING · 19,312 people · 2023 | 2/3 | UCMR-5 |
| Pfhxa | 0.0031 µg/L No EPA limit set Main supplier: D.C. WATER AND SEWER AUTHORITY · 632,323 people · 2024
Highest in the city: 0.0052 µg/L — JOINT BASE ANACOSTIA - BOLLING · 19,312 people · 2023 | 2/3 | 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 Washington
| Supplier | Population served |
|---|---|
| D.C. WATER AND SEWER AUTHORITY | 632,323 |
| JOINT BASE ANACOSTIA - BOLLING | 19,312 |
| WASHINGTON AQUEDUCT DIVISION. | 0 |
Frequently asked questions about Washington tap water
Is Washington tap water safe to drink?
EPA testing detected 26 contaminants in the water serving Washington. 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 Washington?
3 public water suppliers report drinking-water monitoring for Washington, DC to the EPA. Each is listed above with its population served.
What contaminants are in Washington's water?
The contaminants EPA monitoring detected in Washington include Nitrate, Nitrate-Nitrite, Fluoride, TTHM, Chloroform. 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.