Water quality for ZIP code 20656
St. Mary's County, Maryland, one of 26 ZIP codes in the county. 202 active public water systems serve the county; 46 had an EPA violation in the past three years.
Most likely your provider
Other community water systems in St. Mary's County
37 systems, largest first| System | Serves | Status | Rules violated, 3 yr |
|---|---|---|---|
| Patuxent Naval Air Station (navfac-Wash) |
22,000 | 1 | |
| Town of Leonardtown |
5,000 | 1 | |
| Country Lakes |
3,016 | 1 | |
| Cedar Cove |
2,728 | 1 | |
| Saint Marys College |
2,200 | 1 | |
| Wicomico Shores |
1,262 | 1 | |
| Greenbrier |
1,161 | 1 | |
| Breton Bay |
1,012 | 2 | |
| Lord Calvert Trailer Park |
892 | 1 | |
| Hunting Quarters |
715 | 1 | |
| Rolling Acres |
699 | 1 | |
| Piney Point |
672 | 1 | |
| St. Clements Shores |
620 | 1 | |
| Charlotte Hall |
615 | 1 | |
| Forrest Farm Subdivision |
577 | 1 | |
| Laurel Ridge |
560 | 1 | |
| Persimmon Hills |
514 | 1 | |
| Wilderness Run |
511 | 2 | |
| Lexington Estates |
300 | 0 | |
| Birch Manor |
272 | 1 | |
| Charlotte Hall VA Home |
270 | 1 | |
| Grandview Haven |
269 | 1 | |
| Piney Point Landings |
239 | 1 | |
| Villages at Leonardtown |
239 | 1 | |
| Fenwick Manor |
234 | 1 |
Non-community systems in St. Mary's County (164: schools, campgrounds, workplaces, restaurants)
These systems serve places you visit rather than homes.
About this data
Water systems are matched to St. Mary's County, the county this ZIP code lies in, largest first. Your exact provider depends on your address and connection; the largest community water system in a county is usually the city or town utility.
ZIP code areas and town boundaries come from the U.S. Census Bureau's 2020 ZCTA files.
Source: the U.S. EPA's Enforcement and Compliance History Online system (ECHO), which publishes the federal Safe Drinking Water Information System. EPA's terms and values are shown as published. The Maryland records are from EPA's data refresh of Oct 7, 2026; EPA refreshes this data quarterly, and states report to EPA with a lag of three to six months, so the newest violations may not appear yet. Retrieved from ECHO on Oct 11, 2026.