States → Maryland
State profile · EPA SDWIS + UCMR5
Maryland Drinking Water Quality
3,215 public water systems serve 6,070,211 people across Maryland, with every Safe Drinking Water Act violation and UCMR5 PFAS result on record.
- 3,215
- Water systems
- 60,496
- Total violations
- 79.9%
- Systems w/ a violation
- 60.2%
- PFAS detection rate
The verdict
Across Maryland, 2,569 of 3,215 water systems (79.9%) carry at least one EPA violation, and 50 of 83 UCMR5-tested systems show PFAS.
- 60,496
- Total EPA violations on record
- 30%
- Health-based (MCL / treatment)
- 79.9%
- Systems with ≥1 violation
- 60.2%
- UCMR5 PFAS detection rate
Water Systems
3,215
Total Violations
60,496
Violation Rate
79.9%
PFAS Detection
60.2%
50 of 83 tested
Violation Composition
How Maryland's 60,496 violations break down by type, per EPA SDWIS classification.
Health-based (18,132) Monitoring/Reporting (42,364)
| Metric | Value | Share |
|---|---|---|
| Public water systems | 3,215 | - |
| Population served | 6,070,211 | - |
| Total violations | 60,496 | 100% |
| Health-based violations | 18,132 | 30.0% |
| Systems with violations | 2,569 | 79.9% |
| PFAS detection rate | 50 of 83 | 60.2% |
Health-based violations indicate the contaminant exceeded an EPA Maximum Contaminant Level (MCL) or treatment-technique requirement. Monitoring/reporting violations indicate procedural issues (missed tests, late reports) - not necessarily a contamination event.
Largest Water Systems
Washington Suburban Sanitary Commission
Laurel, MD · 1,900,000 served
City of Baltimore
Baltimore, MD · 1,600,000 served
Glen Burnie-Broadneck
Millersville, MD · 290,606 served
Howard County D.p.w. Distribution
Columbia, MD · 286,158 served
Harford County D.p.w.
Abingdon, MD · 104,567 served
City of Hagerstown
Hagerstown, MD · 92,200 served
Waldorf - Charles County Dpw
La Plata, MD · 84,296 served
New Design - Frederick County
Frederick, MD · 74,911 served
Crofton-Odenton
Millersville, MD · 62,986 served
Fort George G. Meade
Fort Meade, MD · 62,234 served
City of Frederick
Frederick, MD · 54,000 served
City of Rockville
MD · 52,000 served
Lexington Park
California, MD · 43,030 served
City of Westminster
Westminster, MD · 35,256 served
City of Annapolis
Annapolis, MD · 35,000 served
City of Salisbury
Salisbury, MD · 30,343 served
Town of Ocean City
Ocean City, MD · 30,000 served
City of Cumberland
Cumberland, MD · 27,039 served
City of Bowie
Bowie, MD · 25,000 served
Freedom District
Westminster, MD · 24,867 served
Most Violations
#1 Reckley Spring Community Water East Greenville
555 #2 Ewell Waterworks Cooperative Tylerton
495 #3 Golden Kay Apartments Elkton
490 #4 Tylerton Waterwork Cooperative Tylerton
460 #5 Hill Waterworks Cooperative Tylerton
459 #6 Midtown Waterworks Cooperative Tylerton
455 #7 Rhodes Point South Waterworks Tylerton
444 #8 Cedar Mobile Home Park Columbia
348 #9 Bb Apartments (Prev Woc Village Apts) Ocean City
308 #10 Town of Princess Anne Princess Anne
305 #11 Barrelville Mt. Savage
301 #12 Thunderbird Motel Newburg
301 #13 Swann Haven Mobile Home Park Chester
280 #14 Reliance Mobile Home Park
265 #15 Amelano Manor Frederick
265 Counties in Maryland
Montgomery
56 systems · 1,971,831 served
· 1,796 violations
Baltimore city
13 systems · 1,608,056 served
· 122 violations
Anne Arundel
425 systems · 567,204 served
· 5,956 violations
Howard
88 systems · 309,588 served
· 985 violations
Harford
238 systems · 217,578 served
· 3,670 violations
Frederick
220 systems · 215,362 served
· 3,555 violations
Charles
171 systems · 143,656 served
· 3,860 violations
Carroll
224 systems · 132,585 served
· 3,560 violations
Washington
89 systems · 127,174 served
· 1,539 violations
St. Mary's
200 systems · 125,614 served
· 2,495 violations
Worcester
139 systems · 95,000 served
· 2,846 violations
Calvert
226 systems · 83,754 served
· 3,228 violations
Cecil
197 systems · 70,068 served
· 6,007 violations
Allegany
59 systems · 68,967 served
· 1,901 violations
Wicomico
98 systems · 58,618 served
· 2,635 violations
Prince George's
38 systems · 56,734 served
· 1,362 violations
Baltimore
276 systems · 46,635 served
· 3,504 violations
Queen Anne's
100 systems · 31,903 served
· 1,478 violations
Talbot
41 systems · 30,121 served
· 1,179 violations
Dorchester
75 systems · 25,599 served
· 1,468 violations
Garrett
80 systems · 25,122 served
· 943 violations
Kent
58 systems · 20,499 served
· 1,297 violations
Caroline
64 systems · 19,836 served
· 2,080 violations
Somerset
37 systems · 18,632 served
· 3,029 violations
Drinking Water Guides
Frequently Asked Questions
How many water systems are in Maryland? ▼
Maryland has 3,215 public water systems serving approximately 6,070,211 people. These include community water systems, non-transient non-community systems, and transient non-community systems regulated under the Safe Drinking Water Act.
How many drinking water violations are in Maryland? ▼
Maryland has 60,496 total drinking water violations on record, with 18,132 classified as health-based violations. 79.9% of water systems in the state have at least one violation.
Has PFAS been found in Maryland drinking water? ▼
Of 83 water systems tested for PFAS in Maryland, 50 had PFAS detected, a 60.2% detection rate. PFAS are persistent "forever chemicals" that do not break down in the environment.
What is the violation rate for Maryland water systems? ▼
Maryland's violation rate is 79.9%. This measures the percentage of public water systems that have at least one recorded violation in the EPA SDWIS database, including both health-based and monitoring/reporting violations.
Where does this Maryland water data come from? ▼
All drinking water data comes from the EPA Safe Drinking Water Information System (SDWIS) and the UCMR5 PFAS monitoring program. SDWIS is the federal database that tracks compliance for all public water systems regulated under the Safe Drinking Water Act.
Data Sources & Methodology
Drinking water violation data from the EPA Safe Drinking Water Information System (SDWIS). PFAS testing data from the UCMR5 monitoring program. SDWIS tracks all public water systems regulated under the Safe Drinking Water Act.
Read our methodology - how this data is sourced, computed, and verified.
Related
Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater Editorial
Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This page draws directly on EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.