District of Columbia water quality
District of Columbia has 24 active public water systems (45 on file total), 11 of them graded by TapGraded.
Grade distribution
Biggest water systems
D.C. WATER AND SEWER AUTHORITY
WASHINGTON, DC · 632,323 served
NATIONAL AIRPORT
WASHINGTON, DC · 28,055 served
JOINT BASE ANACOSTIA - BOLLING
WASHINGTON, DC · 19,312 served
NAVAL STATION WASHINGTON - WNY
WASHINGTON NAVY YARD, DC · 16,800 served
Wingate Elementary School (New) - BIE
Washington, DC · 800 served
Fort Wingate Community
Washington, DC · 550 served
Eastern Navajo Agency - BIE
Washington, DC · 455 served
Baca (Dlo-ay Ashi) Community School - BIE
Washington, DC · 424 served
BIE CHEMAWA INDIAN SCHOOL
WASHINGTON, DC · 320 served
NAVAL OBSERVATORY
WASHINGTON NAVY YARD, DC · 250 served
Lowest-graded systems
Active, graded systems serving at least 10,000 people, ordered by lowest Tap Grade first.
Cities in District of Columbia
Source: EPA SDWIS/ECHO · Data as of 2026Q2