Maryland drinking water quality
Maryland has 3,216 active public water systems serving 6.1 million people. 930 of them, 29%, had at least one EPA violation in the past three years, 81 have an unresolved violation today, and 16 are designated serious violators by the EPA.
Active systems
3,216
in 24 counties
People served
6.1M
460 community systems serve 5.5M
Violations, past 3 years
930
29% of active systems
Serious violators
16
32 systems carry a health flag
Largest counties
All 24 counties| County | People served | Systems | With violations |
|---|---|---|---|
| Montgomery | 1,972,336 | 57 | 19 |
| Baltimore city | 1,610,114 | 14 | 3 |
| Anne Arundel | 571,294 | 424 | 133 |
| Howard | 310,671 | 88 | 15 |
| Frederick | 218,361 | 218 | 28 |
| Harford | 217,710 | 237 | 99 |
| Charles | 143,440 | 172 | 96 |
| Carroll | 129,866 | 224 | 25 |
| Washington | 127,260 | 91 | 34 |
| St. Mary's | 125,704 | 202 | 46 |
Largest community water systems
All 3,216 systems| System | Serves | Status |
|---|---|---|
| Washington Suburban Sanitary Commission Montgomery County |
1,900,000 | |
| City of Baltimore Baltimore city |
1,600,000 | |
| Glen Burnie-Broadneck Anne Arundel County |
290,606 | |
| Howard County D.p.w. Distribution Howard County |
286,158 | |
| Harford County D.p.w. Harford County |
104,567 | |
| City of Hagerstown Washington County |
92,200 | |
| Waldorf Charles County Dpw Charles County |
84,296 | |
| New Design Frederick County Frederick County |
74,911 | |
| Crofton-Odenton Anne Arundel County |
62,986 | |
| Fort George G. Meade Anne Arundel County |
62,234 |
About the Maryland data
Retrieved from EPA ECHO on Oct 11, 2026. EPA records for Maryland systems do not include town names, so searches here match on ZIP code, street address, or county.