County · Maryland
St. Mary's County, Maryland: drinking water records
This overview covers 26 ZIP codes and 37 community water systems in St. Mary's County. It also stands in for 13 ZIP codes whose utility has too little EPA data for a page of its own.
System population figures are summed from EPA registry records and can overlap where wholesalers and retail systems serve the same people. They are not a Census county-population estimate.
Water systems with the most complete records
| Water system | People served | PFAS survey results | PFAS found | Health-based violations | Lead, 9 in 10 homes at or below |
|---|---|---|---|---|---|
| Charlotte Hall VA Home MD0180217 | 270 | 60 | 0 | 1 | 4.5 ppb |
| Lexington Park MD0180007 | 43,030 | 120 | 0 | 0 | 0 ppb |
| Patuxent Naval Air Station (Navfac-Wash) MD0180022 | 22,000 | 780 | 0 | 0 | 0 ppb |
| Saint Marys College MD0180013 | 2,200 | 0 | 0 | 1 | 0 ppb |
| Lord Calvert Trailer Park MD0180213 | 892 | 0 | 0 | 1 | 0 ppb |
| Piney Point MD0180034 | 672 | 60 | 0 | 0 | 0 ppb |
| Langley Mobile Home Park MD0180212 | 175 | 0 | 0 | 1 | 5 ppb |
| Mount Pleasant Water Co., INC. MD0180009 | 150 | 0 | 0 | 2 | 0 ppb |
| Christmas Tree Farm Trailer Park MD0180206 | 100 | 0 | 0 | 3 | 0 ppb |
| Town of Leonardtown MD0180006 | 5,000 | 0 | 0 | 0 | 0 ppb |
| Country Lakes MD0180023 | 3,016 | 0 | 0 | 0 | 0 ppb |
| Cedar Cove MD0180002 | 2,728 | 0 | 0 | 0 | 0 ppb |
| Wicomico Shores MD0180018 | 1,262 | 0 | 0 | 0 | 0 ppb |
| Greenbrier MD0180045 | 1,161 | 0 | 0 | 0 | 0 ppb |
| Breton Bay MD0180001 | 1,012 | 0 | 0 | 0 | 0 ppb |
| Hunting Quarters MD0180038 | 715 | 0 | 0 | 0 | 0 ppb |
| Rolling Acres MD0180017 | 699 | 0 | 0 | 0 | 0 ppb |
| St. Clements Shores MD0180012 | 620 | 0 | 0 | 0 | 0 ppb |
| Charlotte Hall MD1180005 | 615 | 0 | 0 | 0 | 0 ppb |
| Forrest Farm Subdivision MD0180054 | 577 | 0 | 0 | 0 | 0 ppb |
| Laurel Ridge MD0180037 | 560 | 0 | 0 | 0 | 0 ppb |
| Persimmon Hills MD0180046 | 514 | 0 | 0 | 0 | 0 ppb |
| Wilderness Run MD0180036 | 511 | 0 | 0 | 0 | 0 ppb |
| Birch Manor MD0180015 | 272 | 0 | 0 | 0 | 0 ppb |
| Grandview Haven MD0180059 | 269 | 0 | 0 | 0 | 0 ppb |
ZIP reports in St. Mary's County
No ZIP report in this county is published yet.
These ZIP codes are covered by this overview because their utility has too little EPA data for a separate page: 20606, 20618, 20621, 20624, 20626, 20628, 20630, 20656, 20660, 20680, 20684, 20687, 20692.
Sources and scope
EPA UCMR 5 occurrence data, samples collected 2023-01-03 – 2026-06-17, final release, August 2026 (file dated Aug 28, 2026); EPA SDWIS via ECHO, 2026Q2 extract (file dated Jul 9, 2026); EPA service-area boundaries v3.0; Census 2020 ZCTAs. Page generated 2026-09-03.
Counts cover the systems that report this county to EPA. A water system may cross county lines. "Found" means at least one result at or above the laboratory reporting level; it is not a compliance finding.