Washington, District of Columbia Tap Water Quality Report
Serving utility: D.C. Water and Sewer Authority
Updated March 2026 • Data from EWG Tap Water Database & EPA SDWIS
High Priority Concerns
Washington tap water has 14 contaminants exceeding EWG health guidelines, including Haloacetic acids (HAA9), Haloacetic acids (HAA5), Total trihalomethanes (TTHMs). Additionally, 13 known or suspected carcinogens were detected, including Haloacetic acids (HAA9), Haloacetic acids (HAA5), Total trihalomethanes (TTHMs).
Water Provider Information
Contaminants Detected
| Contaminant | Detected Level | EWG Guideline | Legal Limit | Status |
|---|---|---|---|---|
| Haloacetic acids (HAA9) carcinogen | 42.40 ppb | 0.06 ppb | No legal limit | Above guideline |
| Haloacetic acids (HAA5) carcinogen | 31.40 ppb | 0.10 ppb | 60 ppb | Above guideline |
| Total trihalomethanes (TTHMs) carcinogen | 46.40 ppb | 0.15 ppb | 80 ppb | Above guideline |
| Bromodichloromethane carcinogen | 11.90 ppb | 0.06 ppb | No legal limit | Above guideline |
| Bromochloroacetic acid | 3.57 ppb | 0.02 ppb | No legal limit | Above guideline |
| Trichloroacetic acid carcinogen | 14.70 ppb | 0.10 ppb | No legal limit | Above guideline |
| Chloroform carcinogen | 31.40 ppb | 0.40 ppb | No legal limit | Above guideline |
| Dichloroacetic acid carcinogen | 14.90 ppb | 0.20 ppb | No legal limit | Above guideline |
| Dibromochloromethane carcinogen | 3.08 ppb | 0.10 ppb | No legal limit | Above guideline |
| Arsenic* carcinogen | 0.11 ppb | 0.00 ppb | 10 ppb | Above guideline |
| Nitrate carcinogen | 1.97 ppm | 0.14 ppm | 10 ppm | Above guideline |
| Radium, combined (-226 and -228)* | 0.38 pCi/L | 0.05 pCi/L | 5 pCi/L | Above guideline |
| Chromium (hexavalent) carcinogen | 0.09 ppb | 0.02 ppb | No legal limit | Above guideline |
| Chlorate | 260.60 ppb | 210 ppb | No legal limit | Above guideline |
| 2,4-D* | 0.03 ppb | 20 ppb | 70 ppb | Below guideline |
| Aluminum* | 39.20 ppb | 600 ppb | No legal limit | Below guideline |
| Atrazine* | 0.03 ppb | 0.10 ppb | 3 ppb | Below guideline |
| Barium* | 36.40 ppb | 700 ppb | 2,000 ppb | Below guideline |
| Bromoform* carcinogen | 0.01 ppb | 0.50 ppb | No legal limit | Below guideline |
| Dalapon* | 0.10 ppb | N/A | 200 ppb | Below guideline |
| Dibromoacetic acid | 0.01 ppb | 0.03 ppb | No legal limit | Below guideline |
| Diethyl phthalate* | 0.19 ppb | N/A | No legal limit | Below guideline |
| Fluoride* | 0.66 ppm | N/A | 4 ppm | Below guideline |
| Lithium* | 1.76 ppb | N/A | No legal limit | Below guideline |
| Manganese | 0.44 ppb | 100 ppb | No legal limit | Below guideline |
| Metolachlor* | 0.02 ppb | N/A | No legal limit | Below guideline |
| Molybdenum | 0.28 ppb | 40 ppb | No legal limit | Below guideline |
| Monobromoacetic acid | 0.09 ppb | 25 ppb | No legal limit | Below guideline |
| Monochloroacetic acid | 1.66 ppb | 53 ppb | No legal limit | Below guideline |
| Perchlorate* | 0.25 ppb | 1 ppb | No legal limit | Below guideline |
| Perfluorohexanoic Acid (PFHxA) | 0.52 ppt | 1,000 ppt | No legal limit | Below guideline |
| Perfluoropentanoic Acid (PFPeA) | 1.52 ppt | 1,000 ppt | No legal limit | Below guideline |
| Simazine* | 0.00 ppb | 0.10 ppb | 4 ppb | Below guideline |
| Strontium | 0.17 ppb | 1,500 ppb | No legal limit | Below guideline |
| Tritium* | 83.70 pCi/L | 400 pCi/L | No legal limit | Below guideline |
| Uranium* carcinogen | Detected pCi/L | 0.43 pCi/L | 20 pCi/L | Below guideline |
| Vanadium | 0.35 ppb | 21 ppb | No legal limit | Below guideline |
Health Context
Haloacetic acids (HAA9) carcinogen
Exposure to elevated levels of this contaminant may pose health risks. See EWG and EPA guidelines for more information.
Haloacetic acids (HAA5) carcinogen
Exposure to elevated levels of this contaminant may pose health risks. See EWG and EPA guidelines for more information.
Total trihalomethanes (TTHMs) carcinogen
Exposure to elevated levels of this contaminant may pose health risks. See EWG and EPA guidelines for more information.
Bromodichloromethane carcinogen
Bromodichloromethane is a trihalomethane (THM) disinfection byproduct that damages liver and kidneys with chronic exposure. EPA classifies it as a probable human carcinogen based on animal carcinogenicity data.
Bromochloroacetic acid
Exposure to elevated levels of this contaminant may pose health risks. See EWG and EPA guidelines for more information.
Recommended Filtration for This Water
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Shop Hydrogen FlaskFrequently Asked Questions
Is Washington tap water safe to drink?
Washington tap water meets EPA legal standards for drinking water. However, 14 contaminants exceed stricter EWG health guidelines, and 13 known carcinogens were detected. While legally compliant, additional filtration is recommended for optimal safety.
What contaminants are in Washington water?
A total of 37 contaminants were detected in Washington tap water, including Haloacetic acids (HAA9), Haloacetic acids (HAA5). Of these, 14 exceed EWG health guidelines.
What's the best water filter for Washington?
For Washington tap water, we recommend a reverse osmosis (RO) system for drinking water — it removes up to 99.9% of contaminants including heavy metals, PFAS, and disinfection byproducts. For shower and bath water, a whole-home filtration system reduces chlorine and volatile organics.
Where does Washington get its water?
Washington tap water is provided by D.C. Water and Sewer Authority, serving approximately 632,323 people. For detailed source water information, contact your local utility or visit the EPA's SDWIS database.
Nearby City Water Reports
Data sources: Environmental Working Group (EWG) Tap Water Database, U.S. EPA Safe Drinking Water Information System (SDWIS)
Last updated: March 2026
Methodology: Contaminant levels are compared against both EPA legal limits (Maximum Contaminant Levels) and EWG health guidelines, which are often stricter and based on the latest scientific research.
