Tap water in District of Columbia: EPA PFAS results by water system

3 public water systems in District of Columbia were sampled in EPA's UCMR 5 programme (2023–2025); we show six PFAS and lithium. Read 2026-10-31.

0 of 3 systems had at least one sample above a 2024 federal limit; 1 had at least one PFAS found above the reporting level; 2 had none found above the reporting level.

A single sample above a 2024 limit is a measurement, not a violation. Compliance is judged on running yearly averages, and water systems have until 2029 to meet the limits. On 20 May 2026 EPA proposed giving qualifying systems until 2031 for PFOA and PFOS and removing the limits for PFHxS, PFNA and HFPO-DA; those proposals were not final when we last checked (5 Nov 2026). Counts are per system, not per person; population figures are available only for systems serving more than 25,000 people (about 632,323 people across those systems here). UCMR 5 was a one-time national monitoring programme (2023–2025). The results are a snapshot at the system's entry points or taps on the sample dates, not a continuous measurement and not a compliance record.

What this page is: a plain-language restatement of public test results that the US EPA published for the water systems listed below, with the dates of the samples and the date we read them. It describes the system, not the water at your tap, which also depends on the pipes in your building. It is not a safety verdict, not medical advice and not a recommendation to buy anything: "buy nothing" is one of the outcomes in the cost section below. We earn nothing from any link on this page.

Systems with a page on this site

System	People served	UCMR 5 result
D.C. Water and Sewer Authority D.C. Water and Sewer Authority	632,323	None detected (below the reporting level)

Largest other systems sampled in District of Columbia

Pages for these are being added in stages. The data for all 3 systems is in the public dataset.

System	People served	UCMR 5 result
Naval Station Washington - Wny Naval Station Washington - Wny	—	None detected (below the reporting level)
Joint Base Anacostia - Bolling Joint Base Anacostia - Bolling	—	None detected (below the reporting level)

How to use this

Find the system named on your water bill. A city can be served by more than one system; the ZIP finder lists all systems that reported a ZIP code to EPA.
Read the system's yearly water quality report: EPA CCR finder.
Method, sources and the full dataset: data and methodology. Corrections: what changed.