Is St. Leonard, MD Tap Water Safe to Drink?
Graded A, with 2 unresolved violations on record. See what was cited — and what it means for your tap. What to do next ↓
93.8/100
waterverge.com St. Leonard, MD — Water Quality Report
St. Leonard's drinking water received a grade of A (93.8 out of 100), indicating excellent water quality. The city's 1 water system serves approximately 2,000 residents using groundwater.
Lead levels were measured at 1.5 ppb (90th percentile), well within EPA limits. This system has not yet been tested for PFAS under the EPA UCMR 5 program.
The system has 22 violations on record, including 0 health-based violations. 2 remain unresolved.
What to know about St. Leonard's water
St. Leonard ranks #4 out of 107 cities in Maryland for water quality, placing it one of the best in the state.
St. Leonard relies on groundwater, which is generally less vulnerable to surface contamination but can be affected by naturally occurring minerals like arsenic and nitrate, as well as agricultural and industrial runoff.
As a small community water system, St. Leonard may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
Water quality score
See methodology →Is St. Leonard, MD water safe to drink?
St. Leonard's tap water meets most EPA standards but has areas that warrant attention. With a grade of A (93.8/100), some contaminant levels or compliance issues suggest that residents may benefit from additional filtration. The city's 1 water system serves approximately 2,000 residents using groundwater (wells).
Recent water quality updates for St. Leonard
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into St. Leonard's water quality assessment. Grade: A (93.8/100).
Federal disaster declaration (FEMA DR-4583). Hurricane event — may have impacted local water infrastructure.
Federal disaster declaration (FEMA DR-4091). Hurricane event — may have impacted local water infrastructure.
Contaminants: Stage 2 Disinfectants and Disinfection Byproducts Rule.
Contaminants: Consumer Confidence Rule.
Contaminants: Thallium, Total, Selenium, Barium.
Key contaminant findings
Based on the most recent EPA sampling data for St. Leonard's water supply.
Well within EPA limits.
Violation history
St. Leonard's water system has 22 total violations on record, including 0 health-based violations. 2 remain unresolved.
Flood & environmental risk
Calvert County has experienced 10 federally declared disasters since 1972. Flooding and severe storms can overwhelm water treatment plants, cause sewage overflows, and introduce agricultural runoff, bacteria, and sediment into drinking water supplies.
Where does St. Leonard's water come from?
St. Leonard's drinking water comes from groundwater (wells), supplied by 1 water system serving approximately 2,000 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate.
What St. Leonard residents can do
Your water utility is required to publish an annual Consumer Confidence Report (CCR) with detailed testing results. Ask for the latest copy or check your utility's website.
St. Leonard's area has a history of flooding. After severe weather, watch for boil water advisories from your local utility.
Data: EPA SDWIS, UCMR 5 (PFAS), FEMA, NOAA. Last updated May 2026.
Top contaminants to know
View all ↓Violation summary
Violations & advisories
Top industrial polluters within 10 miles of St. Leonard
Industrial polluters nearby
Reported releases to surface water by facilities near St. Leonard, ranked by pounds discharged annually.
| Facility | Top chemical | To surface water (lbs/yr) | Distance |
|---|---|---|---|
SMO BARSTOW PLANT PRINCE FREDERICK, MD20678 | — | — | 8.5 mi |
Source: EPA Toxic Release Inventory (TRI) 2023
Drought conditions
D2 — severe droughtCalvert County is currently in D2 (severe drought) per the U.S. Drought Monitor (week of May 5, 2026). Drought can elevate disinfection-byproduct (TTHM/HAA5) levels and taste/odor issues as utilities draw from lower reservoirs.
Source: U.S. Drought Monitor, updated weekly by NDMC, USDA, and NOAA.
Flood & disaster history
Calvert County has experienced 10 federally declared disasters since 1972. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.
Full contaminants report
| Contaminant | Detected Level | EPA Limit | Unit | Category | Status |
|---|---|---|---|---|---|
| Lead (90th percentile) LeadHeavy Metal A toxic heavy metal that can leach into drinking water from older pipes, solder, and fixtures. No amount of lead in water is considered safe. Health EffectsBrain and nervous system damage in children, kidney damage, high blood pressure, and reproductive problems in adults. EPA Limit15 ppb action level Common SourcesCorrosion of lead pipes, lead solder, brass faucets, and household plumbing. | 1.5 | 15 | ppb | Inorganic | Safe |
Lead level trend (90th percentile)
See how St. Leonard compares by contaminant
Explore where St. Leonard ranks among all Maryland cities for specific contaminants.
Water source & infrastructure
Where St. Leonard's water comes from
St. Leonard's drinking water is drawn from underground aquifers through wells.
Groundwater is naturally filtered through rock and soil layers, generally requiring less treatment than surface water. However, it can contain naturally occurring contaminants like arsenic, radon, and minerals.
Agricultural activity, septic systems, and industrial operations near well fields can introduce nitrates, pesticides, and volatile organic compounds.
The system is operated by private ownership and serves approximately 2,000 people through 1 water system.
Water systems serving St. Leonard
| System Name | PWSID | Population | Source |
|---|---|---|---|
| BEACHES WATER CO-OPERATIVE | MD0040009 | 2,000 | GW |
How St. Leonard compares
Full Maryland rankings →St. Leonard's score of 93.8/100 is above the average of 60/100 among major Maryland cities. It outscores 9 of 10 nearby cities.
Nearby cities
View Maryland rankings →About St. Leonard, MD
Wikipedia →St. Leonard is a census-designated place (CDP) in Calvert County, Maryland, United States. The population was 742 at the 2010 census. Residents of the Calvert Beach and Long Beach communities also use the St. Leonard ZIP code designation.
Learn more about your water
Guides and resources related to St. Leonard's water quality findings.
Explore water quality across Calvert
Frequently asked questions
Is St. Leonard, MD tap water safe to drink?
St. Leonard's water quality earned a grade of A (93.8/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #4 out of 107 cities tested in Maryland.
What contaminants are in St. Leonard's water?
Lead was measured at 1.5 ppb (90th percentile). 22 violations are on record.
How is St. Leonard's water quality grade calculated?
The grade is based on four factors: violation history (40%), lead and copper levels (25%), PFAS contamination (25%), and regulatory compliance (10%). The score is also adjusted based on how complete the available data is. See our methodology page for full details.
Do I need a water filter in St. Leonard?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does St. Leonard's water come from?
St. Leonard's water is sourced from Groundwater. The city has 1 water system serving approximately 2,000 residents.
Is St. Leonard's groundwater at risk of contamination?
St. Leonard uses groundwater, which can be affected by naturally occurring contaminants like arsenic, radon, and nitrate, as well as agricultural runoff and industrial activity. The system has 22 violations on record that may relate to groundwater quality. Groundwater systems are generally less susceptible to surface contamination but should be monitored for emerging contaminants like PFAS.
How does St. Leonard's water compare to other cities?
St. Leonard ranks #4 out of 107 cities in Maryland (better than 96% of state cities) and #721 out of 15744 cities nationally (95th percentile). The grade of A reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.
Does St. Leonard's small water system affect quality?
St. Leonard's system serves approximately 2,000 residents. Small community water systems (under 3,300 people) may have fewer financial resources for infrastructure upgrades and advanced treatment technologies. However, they are held to the same EPA drinking water standards as larger systems. This system has 22 violations on record.