State profile · EPA SDWIS + UCMR5
Maryland Drinking Water Quality
3,215 SDWIS-listed systems serve 6,070,211 people. UCMR5 PFAS detection is 36.1% on the tested subset (upper-third UCMR5 detection (> 35.3%)); SDWIS violation rate is 79.9%.
- 3,215
- SDWIS water systems
- 60,496
- Total violations
- 79.9%
- SDWIS systems w/ a violation
- 36.1%
- UCMR5 PFAS rate (83 tested)
The verdict
UCMR5 PFAS detection is 36.1% (30 of 83 tested) - upper-third UCMR5 detection (> 35.3%). According to EPA SDWIS population served, Maryland ranks #19 of 66 states and territories by people served through public water systems.
- #19 of 66
- Population · states corpus
- 60,496
- Total EPA violations on record
- 30%
- Health-based (MCL / treatment)
- 79.9%
- SDWIS systems with ≥1 violation
SDWIS violation % and UCMR5 PFAS % use different denominators (full inventory vs tested subset). Population ordinal uses SDWIS population served.
Maryland standing, low SDWIS violation-rate third
Maryland is in the lower third of jurisdictions by violation rate (79.9%; lower-third rate (≤ 92.5%)). That is a relative placement among peers, not a claim that most systems are clean - 2,569 of 3,215 still carry ≥1 record. Population served is large (6,070,211; larger served population (> 5,131,439)), so household exposure scale sits behind inventory and rate. Health-based share is 30% - a material slice is exposure-relevant, with the rest monitoring or reporting. UCMR5 PFAS detection is 36.1% on the tested subset (upper-third UCMR5 detection (> 35.3%)) - a different denominator from the SDWIS violation rate. Systems listed below are ranked by population served or violation count; pair rate with inventory size before reading exposure scale.
Nationwide similar states
Nearest by SDWIS violation rate
Nearest by population served
Health-based share of this violation record
EPA SDWIS classifications for Maryland's 60,496 recorded violations.
Maryland vs nearest violation-rate peers
Share of SDWIS-listed systems with at least one recorded violation; peers are nearest by absolute rate distance, not a fixed top-seven list.
- MD
Maryland
79.9 % of systems
- HI
Hawaii
80.3 % of systems
- IL
Illinois
80.8 % of systems
- VI
US Virgin Islands
83.6 % of systems
- DE
Delaware
74.8 % of systems
What this shows Maryland's rate is 79.9% (2,569 of 3,215 systems; lower-third rate (≤ 92.5%)). This is a comparison of recorded SDWIS violations, not a measure of current water safety.
Maryland vs all jurisdictions by SDWIS system inventory
Where this state's public water system count sits among every state and territory on PlainWater
3,215 15th of 66 higher than 51 of 66 jurisdictions
States and territories, banded by SDWIS-listed public water system count
Each bar is a band; taller bars hold more jurisdictions. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.
Source EPA SDWIS state aggregates · 2026-05-15
Largest Water Systems
Most Violations
Counties in Maryland
Context: PFAS in drinking water · methodology · all states
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.