District of Columbia Water Quality
District of Columbia, District of Columbia: one city report built from EPA and utility records. A county has many suppliers; each city shows the system that serves it.
Highest result for each contaminant
One row per contaminant: the highest result any system in the county reported, against its limit. Open a row for the systems behind it.
Water hardnessD.C. WATER AND SEWER AUTHORITYAesthetic, no federal health limit · USGS7.4 gpg
- D.C. WATER AND SEWER AUTHORITY7.4 gpgReporting year: 2025
Lead (90th percentile)D.C. WATER AND SEWER AUTHORITY15 µg/L federal action level · US EPA2 µg/L
- D.C. WATER AND SEWER AUTHORITY2 µg/LMonitoring period: 2026–2026 (still open)
Perfluorohexanoic acid (PFHxA)D.C. WATER AND SEWER AUTHORITY400,000 ng/L Michigan EGLE state MCL (strictest US state) · Michigan EGLE3.1 ng/L
- D.C. WATER AND SEWER AUTHORITY3.1 ng/LSample date: 2024-02-07 to 2024-10-16
Perfluoropentanoic acid (PFPeA)D.C. WATER AND SEWER AUTHORITYNo federal or state limit; shown for transparency4.7 ng/L
- D.C. WATER AND SEWER AUTHORITY4.7 ng/LSample date: 2024-02-07 to 2024-10-16
28 substances tested, none detected in this systemShow
Tested in this system: D.C. WATER AND SEWER AUTHORITY
- 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS)
- 1H, 1H, 2H, 2H-perfluorodecane sulfonic acid (8:2 FTS)
- 1H, 1H, 2H, 2H-perfluorohexane sulfonic acid (4:2 FTS)
- 1H, 1H, 2H, 2H-perfluorooctane sulfonic acid (6:2 FTS)
- 4,8-Dioxa-3H-perfluorononanoic acid (ADONA)
- 9-Chlorohexadecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS)
- Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals)
- Lithium
- N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA)
- N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA)
- Nonafluoro-3,6-dioxaheptanoic acid (NFDHA)
- Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA)
- Perfluoro-3-methoxypropanoic acid (PFMPA)
- Perfluoro-4-methoxybutanoic acid (PFMBA)
- Perfluorobutanesulfonic acid (PFBS)
- Perfluorobutanoic acid (PFBA)
- Perfluorodecanoic acid (PFDA)
- Perfluorododecanoic acid (PFDoA)
- Perfluoroheptanesulfonic acid (PFHpS)
- Perfluoroheptanoic acid (PFHpA)
- Perfluorohexanesulfonic acid (PFHxS)
- Perfluorononanoic acid (PFNA)
- Perfluorooctanesulfonic acid (PFOS)
- Perfluorooctanoic acid (PFOA)
- Perfluoropentanesulfonic acid (PFPeS)
- Perfluorotetradecanoic acid (PFTA)
- Perfluorotridecanoic acid (PFTrDA)
- Perfluoroundecanoic acid (PFUnA)
Cities ranked by the records
Ranked by the Purity Score of each city's main water system, highest first. Scores belong to water systems; there is no county score. The score is computed only from contaminants measured in the published EPA record, so this ranks the record, not which city's water is safest. How the score works.
0of 1 city above the 15 µg/L action level
Based on each system's 90th-percentile result. Lead from household plumbing isn't in this record.
Lead in District of Columbia1city reports hardness · Washington, DC, 7.4 gpg
Hard on the USGS scale. An aesthetic measure with no federal health limit.
Hard water explainedLargest water systems
- Washington, DCD.C. WATER AND SEWER AUTHORITY · DC0000002632,323 served
Frequently asked
How does District of Columbia tap water compare across cities?
PurityMap ranks 1 city in District of Columbia by the Purity Score of each city's main water system, computed only from contaminants measured in the published EPA record. Scores belong to water systems, not to cities. The highest published score is Washington, DC's main water system: D.C. WATER AND SEWER AUTHORITY · PWSID DC0000002 · Purity Score 98 (Excellent) · Confidence: moderate · Assessed at the water-system level. The ranking compares the records, not which city's water is safest, and your own tap can differ with household plumbing.
How many District of Columbia cities had a PFAS sample above a 2024 EPA limit?
None of the 1 District of Columbia city report had a PFAS sample above a 2024 EPA limit in EPA's UCMR 5 testing. PFAS were detected below the limit in 1.
Is there lead in District of Columbia tap water?
Utilities report lead as a 90th-percentile result from home taps. 1 of 1 District of Columbia cities reported a value above zero, and none was above the 15 µg/L federal action level. Lead usually comes from a building's own pipes and fixtures, so only a test at your tap tells you what you drink.
Does District of Columbia have hard water?
Hardness is published in utility water-quality reports for 1 District of Columbia city on record; the hardest is Washington, DC at 7.4 grains per gallon. Hardness affects scale and appliances; it is not a health finding.
Follow District of Columbia's water
Get an email when a city record in the county changes.
Record changes only
We email when places in District of Columbia get new results. Unsubscribe any time.
Follow District of Columbia's water →