District Of Columbia County, DC: drinking water report. The District of Columbia operates as both a city and county equivalent, serving approximately
The District of Columbia operates as both a city and county equivalent, serving approximately 700,000 residents across neighborhoods from Georgetown to Anacostia. DC Water (formally the District of Columbia Water and Sewer Authority) supplies drinking water drawn from the Potomac River through the Washington Aqueduct, a federal facility operated by the U.S. Army Corps of Engineers. This shared infrastructure also serves Arlington County and Falls Church in Virginia, making the system a unique federal-local partnership that processes roughly 180 million gallons daily.
The District's water quality challenges center primarily on lead service lines, a legacy of infrastructure installed before 1986. DC Water has documented approximately 23,000 lead service lines remaining in the system, concentrated in older neighborhoods developed before lead pipe bans. The authority learned hard lessons from a lead contamination crisis in the early 2000s, when changes in water treatment chemistry caused lead to leach from pipes at elevated levels. This event prompted ongoing lead monitoring, free water testing programs, and aggressive service line replacement efforts that have accelerated in recent years.
PFAS contamination represents an emerging concern for Potomac River source water. The 2023 EPA UCMR5 monitoring requirements revealed detectable levels of per- and polyfluoroalkyl substances in many Mid-Atlantic surface water systems. While DC Water has reported PFAS detections below current health advisory levels, the compounds' persistence and the Potomac watershed's mixture of urban runoff, industrial sites, and military installations (including Andrews Air Force Base and surrounding federal facilities) create ongoing exposure pathways. The authority has been testing for PFAS beyond federal requirements and evaluating treatment upgrades, though like most utilities drawing from major rivers in developed areas, complete elimination remains technically challenging.
Disinfection byproducts also warrant attention in the District's system. Total trihalomethanes and haloacetic acids, formed when chlorine interacts with organic matter in source water, occasionally approach maximum contaminant levels in parts of the distribution network with longer water residence times. The Potomac's nutrient loading from upstream agricultural areas and stormwater runoff contributes to seasonal fluctuations in organic content. Water age in the system's extremities, combined with the region's warm summers, can elevate byproduct formation despite treatment optimization efforts.
Residents in homes built before 1986 should request free lead testing from DC Water or run cold water for 30 seconds before drinking, especially after periods of non-use. Those concerned about PFAS, lead, or disinfection byproducts should consider point-of-use filtration certified for these specific contaminants. Check your water for current contamination data in your ZIP code, review our water filter guide for certified options that address DC's documented issues, get a detailed report showing detected contaminants in your area, or visit the District of Columbia state page for regulatory context and utility contact information.