St. Marys County Water Quality: 100 Violations (MD)
19 water systems · 14 ZIP codes · Home Safety Score Unavailable · 0 of 28 tracked ZIP records scored · Updated
Data: EPA Safe Drinking Water Information System (SDWIS), EPA ECHO Last verified:
Violation Trend
EPA violations across water systems in St. Mary's County.
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Find the Right Filter →Water Quality Overview
St. Mary's County has 19 community water systems across 14 directly mapped ZIP records. The systems report serving approximately 84,506 people. The available records contain 100 EPA violations, including 5 health-based violations.
Health-based violations account for 5% of all violations in St. Mary's County. These violations indicate contaminant levels that may pose direct risks to human health.
Violation Breakdown
| Violation Type | Count | Percentage |
|---|---|---|
| Health-based | 5 | 5.0% |
| Monitoring/Reporting | 95 | 95.0% |
| Total | 100 | 100% |
Health-based violations indicate contaminant levels exceeding EPA Maximum Contaminant Levels (MCLs). Monitoring violations indicate failures to test or report.
Cities with Most Violations
| Rank | City | Violations | Health-Based | ZIP Codes | Population |
|---|---|---|---|---|---|
| 1 | Lexington Park | 19 | 3 | 1 | 26,799 |
| 2 | Leonardtown | 13 | 0 | 1 | 15,979 |
| 3 | California | 12 | 1 | 1 | 14,743 |
| 4 | Mechanicsville | 11 | 0 | 1 | 23,918 |
| 5 | Hollywood | 11 | 0 | 1 | 10,357 |
| 6 | Great Mills | 9 | 1 | 1 | 6,976 |
| 7 | Patuxent River | 7 | 0 | 1 | 1,577 |
| 8 | Park Hall | 5 | 0 | 1 | 98 |
| 9 | Chaptico | 4 | 0 | 1 | 902 |
| 10 | Clements | 3 | 0 | 1 | 1,157 |
Violation Trend
Year-by-year EPA violations across water systems in St. Mary's County:
| Year | Total | Health-Based |
|---|---|---|
| 2023 | 2 | 2 |
| 2024 | 10 | 10 |
Most Common Contaminants
| Contaminant | Category | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|
| Haloacetic Acids (HAA5) | Disinfection Byproducts | 47 | 14 | No |
| Lead | Inorganic | 20 | 8 | No |
| Stage 2 DBP Rule | Treatment Technique | 18 | 7 | Yes |
| Total Trihalomethanes (TTHM) | Disinfection Byproducts | 9 | 9 | No |
| Stage 1 DBP Rule | Treatment Technique | 4 | 4 | No |
| Nickel | Inorganic | 1 | 1 | No |
| Surface Water Treatment Rule | Treatment Technique | 1 | 1 | No |
Water Data and the Home Safety Score
This page reports EPA water-system facts without converting the broader Home Safety Score into a drinking-water grade. The county Home Safety grade (unavailable) is a separate multi-source index that also requires PFAS screening, radon, and annual air-quality evidence. Check each ZIP report for the versioned score and its component coverage.
Water Systems in St. Mary's County
St. Mary's County is served by 19 community water systems, averaging 0.7 systems per ZIP code. Each system is independently regulated and tested by the EPA. Larger systems serving more people typically have more extensive monitoring requirements.
Water systems in St. Mary's County source water from a mix of surface water (rivers, reservoirs) and groundwater (wells, aquifers). Source type affects which contaminants are most likely to be detected.
How to Check Your Water in St. Mary's County
Enter your ZIP code on ZipCheckup for detailed water-system data including contaminant levels and violation history; the Home Safety Score is shown separately with its model version
Request your CCR — every water utility must provide an annual Consumer Confidence Report
Get a home test — certified kits ($20-$50) or professional lab tests ($150-$400) can detect contaminants not covered by routine testing
Consider filtration — NSF-certified filters can address specific contaminants found in your area
Check for lead — homes built before 1986 should test for lead regardless of utility compliance
EPA Enforcement
The EPA and state regulators have taken 108 enforcement actions against water systems in St. Mary's County. Enforcement actions range from compliance assistance and administrative orders to formal penalties. Systems under enforcement are required to remediate violations and may face ongoing monitoring requirements.
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Enforcement: EPA ECHO
Source publication schedules vary. See the page source and verification fields for available timing evidence.
Water Quality by ZIP Code in St. Mary's County
Water quality varies across St. Mary's County's 14 ZIP codes. Check your specific ZIP for detailed contaminant data.
| ZIP Code | City | Violations | Health | |
|---|---|---|---|---|
| 20653 | Lexington Park | 19 | 3 | View → |
| 20650 | Leonardtown | 13 | 0 | View → |
| 20619 | California | 12 | 1 | View → |
| 20636 | Hollywood | 11 | 0 | View → |
| 20659 | Mechanicsville | 11 | 0 | View → |
| 20634 | Great Mills | 9 | 1 | View → |
| 20670 | Patuxent River | 7 | 0 | View → |
| 20667 | Park Hall | 5 | 0 | View → |
| 20621 | Chaptico | 4 | 0 | View → |
| 20624 | Clements | 3 | 0 | View → |
| 20656 | Loveville | 2 | 0 | View → |
| 20692 | Valley Lee | 2 | 0 | View → |
| 20620 | Callaway | 1 | 0 | View → |
| 20630 | Drayden | 1 | 0 | View → |
Water facts and the Home Safety Score
This page reports water evidence separately. A broader Home Safety Score is not published here unless the versioned model identity and complete required component coverage are available.
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Find the Right Filter →Frequently Asked Questions
Is the tap water safe in St. Mary's County, Maryland?
St. Mary's County has 19 community water systems with 100 recorded EPA violations, including 5 health-based. Water quality varies by ZIP code - check your specific location for detailed results.
How many water violations does St. Mary's County have?
St. Mary's County has 100 total EPA violations across 14 directly mapped ZIP records. 5 are health-based.
Which city in St. Mary's County has the most water violations?
Lexington Park has the most violations in St. Mary's County with 19 recorded EPA violations across 1 ZIP code.
What contaminants are found in St. Mary's County water?
St. Mary's County water systems are monitored for over 90 EPA-regulated contaminants including lead, copper, nitrates, disinfection byproducts, and bacteria. Check your ZIP code for contaminant-specific data.
How can I test my water in St. Mary's County?
Contact your local water utility for free or low-cost testing. You can also use a certified home test kit ($20-$50) or hire a certified lab ($150-$400).