Water Quality Report · Updated October 07, 2026
D.C. WATER AND SEWER AUTHORITY
D.C. WATER AND SEWER AUTHORITY delivers tap water graded C (66/100) by TapWaterSafety.org. The utility serves approximately 632,323 residents in WASHINGTON, District of Columbia using surface water (purchased). 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. For questions, the utility can be reached at 202-364-3131.
Is WASHINGTON tap water safe to drink?
D.C. WATER AND SEWER AUTHORITY delivers tap water that earns a grade of C (66/100) from TapWaterSafety.org — an average rating, with several contaminants above health guidelines but generally compliant with US legal limits.
The utility serves 632,323 residents in WASHINGTON, drawing from surface water (purchased).
Public testing data identifies 14 contaminants in this water above EWG's health-based guidelines, including: Haloacetic acids (HAA9), Haloacetic acids (HAA5), Total trihalomethanes (TTHMs), Bromodichloromethane, Bromochloroacetic acid, Trichloroacetic acid, Chloroform, Dichloroacetic acid, Dibromochloromethane, Arsenic*, Nitrate, Radium, combined (-226 and -228)*, Chromium (hexavalent), Chlorate. For most residents, a properly certified home filter at the kitchen tap is the most cost-effective way to reduce exposure to whatever's in your water. See our filter recommendations below, matched specifically to this utility's contaminant profile.
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.
Quick actions for WASHINGTON residents
Top concerns in this water
Based on the most recent EPA and EWG data, these are the most significant water quality issues for D.C. WATER AND SEWER AUTHORITY.
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.
Contact D.C. WATER AND SEWER AUTHORITY
Reach the utility directly for service issues, water quality concerns, or to request your Consumer Confidence Report.
General Contact
Recommended water filters for WASHINGTON
Filters matched to the specific contaminants in this 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.
Score breakdown
This utility's overall score of 66/100 breaks down across five weighted components. Read the full methodology →
Contaminants detected — international standards comparison
Every contaminant detected, compared side-by-side against US EPA legal limits, the EU Drinking Water Directive (2020/2184), WHO Guidelines, and California's Public Health Goal (the strictest US benchmark). 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 (4th ed.), California OEHHA PHGs, EWG Tap Water Database.
D.C. WATER AND SEWER AUTHORITY service area
This water system serves 1 community in District of Columbia County, District of Columbia. Click any city for its dedicated tap water quality page.
Find the right filter for WASHINGTON water
Browse filter categories by water-quality concern. Each option below is NSF-certified for the matched contaminant type.