Is Washington tap water safe to drink?

D.C. Water and Sewer Authority disinfects with chloramine, according to its own water quality reporting. Chloramine is chlorine bonded with ammonia. It lasts longer in the pipes, which is why utilities use it, but it is much harder to remove at home than plain chlorine. Note: Washington Aqueduct chloramine; annual free chlorine switch about 6 weeks (Mar-May 2026).

Most cheap shower filters use KDF and standard carbon, which barely affect chloramine. Look for vitamin C or catalytic carbon media, and for drinking water, a filter that lists chloramine reduction specifically. If you keep fish, chloramine must be neutralized before it reaches the tank.

Washington's water measures about 6.8 grains per gallon (117 mg/L as calcium carbonate), which is moderately hard on the US Geological Survey scale: soft below 60 mg/L, moderately hard 60-120, hard 120-180, very hard above 180.

At this level a water softener is usually not worth the cost. Spend on filtration for taste or specific contaminants instead.

Hardness data: TapWaterData Water Hardness Dataset (tapwaterdata.com), licensed CC BY 4.0. Underlying source: Utility-reported water quality data — D.C. WATER AND SEWER AUTHORITY (PWSID DC0000002), 2025-10-10.

In D.C. Water and Sewer Authority's most recent lead sampling, for the period ending December 2025, 90% of tested homes came in at or below 2 ppb of lead. That is low on any of the federal yardsticks.

This is a system-wide statistic, not a reading of your tap. Lead comes from lead service lines, old solder and some brass fixtures inside homes, so two houses on the same street can differ. Testing your own tap costs $15-40, and many utilities test free on request.

EPA's lead action level is 15 parts per billion (ppb) today and drops to 10 ppb in November 2027 under the Lead and Copper Rule Improvements. FDA's limit for bottled water is 5 ppb. EPA's health goal for lead is zero.

D.C. Water and Sewer Authority was sampled in EPA's 2023-2025 nationwide survey, and none of the six regulated PFAS compounds were found above the lab reporting limits.

In April 2024 EPA set enforceable limits of 4 parts per trillion (ppt) for PFOA and PFOS, and 10 ppt for PFHxS, PFNA and HFPO-DA (GenX). In May 2025 EPA said it intends to keep the PFOA and PFOS limits, extend the compliance deadline to 2031, and rescind the other three. We compare results to the 2024 limits and label which ones may change.

D.C. Water and Sewer Authority has no health-based violations on file with EPA since 2016.

EPA did not assign a radon zone to District of Columbia. Radon is still worth testing for: it is the leading cause of lung cancer among non-smokers.

EPA radon zones describe counties, not houses. Zone 1 counties have a predicted average indoor level above 4 picocuries per liter (pCi/L), Zone 2 between 2 and 4, Zone 3 below 2. Homes with high levels are found in every zone, which is why EPA recommends that every home be tested, and fixed at 4 pCi/L or above. See every District of Columbia county's radon zone.