Tap Water Quality Report
Tap water quality in Washington, District of Columbia
Tap water in Washington, District of Columbia receives a grade of D (66/100) from TapWaterSafety.org. It's served by D.C. WATER AND SEWER AUTHORITY. The most significant water quality concerns are: Haloacetic acids (HAA9) significantly above health guideline; Haloacetic acids (HAA5) significantly above health guideline; Total trihalomethanes (TTHMs) significantly above health guideline; Arsenic detected. Data sources: EPA SDWIS, EPA ECHO, EWG Tap Water Database.
What's in Washington's tap water
Top water quality concerns identified by the EPA and Environmental Working Group across the utility serving Washington.
Haloacetic acids (HAA9) significantly above health guideline
Moderate concernHaloacetic acids (HAA9) detected at 42.4 ppb, 707x above the EWG health guideline of 0.06 ppb.
Haloacetic acids (HAA5) significantly above health guideline
Moderate concernHaloacetic acids (HAA5) detected at 31.4 ppb, 314x above the EWG health guideline of 0.1 ppb.
Total trihalomethanes (TTHMs) significantly above health guideline
Moderate concernTotal trihalomethanes (TTHMs) detected at 46.4 ppb, 310x above the EWG health guideline of 0.15 ppb.
Arsenic detected
Moderate concernArsenic detected at 0.109 ppb.
EPA compliance record
Official U.S. EPA records for D.C. WATER AND SEWER AUTHORITY (system ID DC0000002) for the last 3 years. Checked 2026-10-07.
Source: U.S. EPA Enforcement and Compliance History Online (ECHO), from the Safe Drinking Water Information System. See EPA's full report.
Recommended filters for Washington
Filters matched to the specific contaminants in Washington's water supply.
Carbon filter certified for VOCs (NSF/ANSI 53)
$180-$599Activated carbon is effective for disinfection byproducts. Look for NSF/ANSI 53 VOC reduction.
Reverse osmosis certified for arsenic (NSF/ANSI 58)
$429-$599Reverse osmosis certified under NSF/ANSI 58 for arsenic is the most reliable home option.
Disclosure: TapWaterSafety earns a commission from purchases made through these links. This does not influence our scoring methodology or filter selection.
All contaminants detected in Washington's tap water
Every contaminant identified, compared side-by-side against US EPA legal limits, the EU Drinking Water Directive (2020/2184), WHO Guidelines, and California's Public Health Goal. Why we show multiple standards →
| Contaminant | Detected | EWG US health-based |
EPA US legal |
EU DWD Europe |
WHO global |
CA PHG strictest US |
Tested sample year |
Status |
|---|---|---|---|---|---|---|---|---|
| Haloacetic acids (HAA9) Disinfection byproduct |
42.4 ppb | 0.06 | — | — | — | — | — | 707× over |
| Haloacetic acids (HAA5) Disinfection byproduct |
31.4 ppb | 0.1 | 60.0 | 60 | — | — | — | 314× over |
| Total trihalomethanes (TTHMs) Disinfection byproduct |
46.4 ppb | 0.15 | 80.0 | 100 | — | — | — | 310× over |
| Bromodichloromethane Disinfection byproduct |
11.9 ppb | 0.06 | — | — | — | — | — | 198× over |
| Bromochloroacetic acid Disinfection byproduct |
3.57 ppb | 0.02 | — | — | — | — | — | 179× over |
| Trichloroacetic acid Disinfection byproduct |
14.7 ppb | 0.1 | — | — | — | — | — | 147× over |
| Chloroform Disinfection byproduct |
31.4 ppb | 0.4 | — | — | — | — | — | 79× over |
| Dichloroacetic acid Disinfection byproduct |
14.9 ppb | 0.2 | — | — | — | — | — | 75× over |
| Dibromochloromethane Disinfection byproduct |
3.08 ppb | 0.1 | — | — | — | — | — | 31× over |
| Arsenic* Heavy metal |
0.109 ppb | 0.004 | 10.0 | 10 | 10 | 0.004 | — | 27× over |
| Nitrate Inorganic |
1.97 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | 14× over |
| Radium, combined (-226 and -228)* Radiological |
0.38 pCi/L | 0.05 | 5.0 | — | — | — | — | 7.6× over |
| Chromium (hexavalent) Heavy metal |
0.0863 ppb | 0.02 | — | — | — | — | — | 4.3× over |
| Chlorate Disinfection byproduct |
260.6 ppb | 210.0 | — | — | — | — | — | 1.2× over |
| Dibromoacetic acid Disinfection byproduct |
0.0146 ppb | 0.03 | — | — | — | — | — | Below guideline |
| Atrazine* Pesticide/Herbicide |
0.0279 ppb | 0.1 | 3.0 | 0.1 | 100 | 0.15 | — | Below guideline |
| Perchlorate* Disinfection byproduct |
0.249 ppb | 1.0 | — | — | — | — | — | Below guideline |
| Tritium* Other |
83.7 pCi/L | 400.0 | — | — | — | — | — | Below guideline |
| Aluminum* Heavy metal |
39.2 ppb | 600.0 | — | 200 | — | 600 | — | Below guideline |
| Barium* Heavy metal |
36.4 ppb | 700.0 | 2000.0 | — | 1300 | 2000 | — | Below guideline |
| Simazine* Pesticide/Herbicide |
0.00458 ppb | 0.1 | 4.0 | — | — | — | — | Below guideline |
| Monochloroacetic acid Disinfection byproduct |
1.66 ppb | 53.0 | — | — | — | — | — | Below guideline |
| Bromoform* Disinfection byproduct |
0.00857 ppb | 0.5 | — | — | — | — | — | Below guideline |
| Vanadium Other |
0.353 ppb | 21.0 | — | — | — | — | — | Below guideline |
| Molybdenum Other |
0.281 ppb | 40.0 | — | — | — | — | — | Below guideline |
| Manganese Heavy metal |
0.444 ppb | 100.0 | — | 50 | 80 | — | — | Below guideline |
| Monobromoacetic acid Disinfection byproduct |
0.0944 ppb | 25.0 | — | — | — | — | — | Below guideline |
| 2,4-D* Pesticide/Herbicide |
0.0348 ppb | 20.0 | 70.0 | — | — | — | — | Below guideline |
| Perfluoropentanoic Acid (PFPeA) PFAS |
1.52 ppt | 1000.0 | — | — | — | — | — | Below guideline |
| Perfluorohexanoic Acid (PFHxA) PFAS |
0.517 ppt | 1000.0 | — | — | — | — | — | Below guideline |
| Strontium Radiological |
0.165 ppb | 1500.0 | — | — | — | — | — | Below guideline |
| Dalapon* Pesticide/Herbicide |
0.104 ppb | — | 200.0 | — | — | — | — | Below guideline |
| Diethyl phthalate* Semi-volatile organic compound |
0.188 ppb | — | — | — | — | — | — | Below guideline |
| Fluoride* Inorganic |
0.657 ppm | — | 4.0 | 1.5 | 1.5 | — | — | Below guideline |
| Lithium* Other |
1.76 ppb | — | — | — | — | — | — | Below guideline |
| Metolachlor* Pesticide/Herbicide |
0.0175 ppb | — | — | — | — | — | — | Below guideline |
| Uranium* Radiological |
0.0 pCi/L | 0.43 | 20.0 | 30 | 30 | 0.43 | — | Below guideline |
All values in the unit of the detected level. Red cells indicate the detected level exceeds that standard. Some contaminants have limits in some jurisdictions but not others (shown as —). The "Tested" column shows the year each contaminant sample was collected.
Sources: US EPA, EU Drinking Water Directive 2020/2184, WHO Guidelines, California OEHHA PHGs, EWG Tap Water Database.
Treatment plant contact info
For service issues, water quality concerns, or to request a Consumer Confidence Report from D.C. WATER AND SEWER AUTHORITY.
General Contact
ZIP codes served
Washington's public water systems serve the following ZIP codes: