Maryland Water Quality Report 2026
Maryland tap water is use filtration based on our analysis of 6 water systems serving 2,117,258 residents. The average PurityMap score is 73.7/100 (Grade: C), which is 4.2 points below the national average.
- PFAS detected in 3 of 6 cities (50%). Forever chemicals require reverse osmosis filtration.
- 1 cities have lead at or above 5 ppb. Homes built before 1986 are at highest risk.
- 6 cities use chloramine or have elevated chlorine residuals. Standard Brita pitchers do not remove chloramine.
We recommend an under-sink reverse osmosis system for drinking water in PFAS-affected areas of Maryland. RO removes 99%+ of PFAS, lead, and other contaminants. For hard water cities, add a whole-house softener.
Moderate
Maryland is 4.2 points below the US average of 77.9/100. Hardness is 1.4 GPG below the US average of 6.3 GPG.
Cities ranked by lowest score. Click any city for the full report and filter recommendations.
| Rank | City | Score | Hardness | Lead | Key Issues |
|---|---|---|---|---|---|
| 1 | Rockville | 67/100 | 4.8 GPG | 3.2 ppb | PFAS (1.8 ppt) |
| 2 | Gaithersburg | 67/100 | 4.8 GPG | 3.0 ppb | PFAS (1.8 ppt) |
| 3 | Bowie | 67/100 | 4.5 GPG | 3.0 ppb | PFAS (1.8 ppt) |
| 4 | Baltimore | 77/100 | 5.6 GPG | 6.8 ppb | Lead (6.8 ppb) |
| 5 | Annapolis | 82/100 | 4.5 GPG | 3.5 ppb | Hardness 4.5 GPG, Lead 3.5 ppb |
| 6 | Frederick | 82/100 | 5.2 GPG | 3.5 ppb | Hardness 5.2 GPG, Lead 3.5 ppb |
How Maryland's 6 cities score on the PurityMap 0–100 scale:
Water quality for the most populated cities. Click any city for details.
| City | Population | Score | Hardness | Key Issues |
|---|---|---|---|---|
| Baltimore | 1.8M | 77/100 | 5.6 GPG | Lead |
| Frederick | 83K | 82/100 | 5.2 GPG | — |
| Rockville | 68K | 67/100 | 4.8 GPG | PFAS |
| Gaithersburg | 67K | 67/100 | 4.8 GPG | PFAS |
| Bowie | 58K | 67/100 | 4.5 GPG | PFAS |
| Annapolis | 41K | 82/100 | 4.5 GPG | — |
Maryland generally has soft to moderate water. Average: 4.9 GPG (Moderate). Most residents do not need a softener.
PFAS have been detected in 3 of 6 cities (50%) in Maryland. Highest: Rockville at 1.8 ppt. Affected: Rockville, Gaithersburg, Bowie. A reverse osmosis filter is recommended.
1 cities in Maryland have lead at or above 5 ppb. Highest: Baltimore at 6.8 ppb. No safe level of lead exists. Cities: Baltimore.
Where Maryland gets its drinking water, based on 6 water systems.
| Source Type | Cities | % of Total |
|---|---|---|
| Surface Water | 5 | 83% |
| Mixed (Ground + Surface) | 1 | 17% |
3 cities have PFAS. Reverse osmosis is the most effective solution.
| # | City | Pop. | Score | Hardness | Lead | PFAS | TDS |
|---|---|---|---|---|---|---|---|
| 1 | Rockville | 68K | 67/100 | 4.8 GPG (Moderate) | 3.2 ppb | ⚠️ Yes (1.8 ppt) | 165 ppm |
| 2 | Gaithersburg | 67K | 67/100 | 4.8 GPG (Moderate) | 3.0 ppb | ⚠️ Yes (1.8 ppt) | 165 ppm |
| 3 | Bowie | 58K | 67/100 | 4.5 GPG (Moderate) | 3.0 ppb | ⚠️ Yes (1.8 ppt) | 160 ppm |
| 4 | Baltimore | 1.8M | 77/100 | 5.6 GPG (Moderate) | 6.8 ppb | ✅ No | 195 ppm |
| 5 | Annapolis | 41K | 82/100 | 4.5 GPG (Moderate) | 3.5 ppb | ✅ No | 175 ppm |
| 6 | Frederick | 83K | 82/100 | 5.2 GPG (Moderate) | 3.5 ppb | ✅ No | 180 ppm |
Maryland has 4 utilities. Major: Baltimore City Dept of Public Works, Frederick County Division of Utilities, Washington Suburban Sanitary Commission, City of Annapolis Water Division.
Sources: Prettyboy Liberty and Loch Raven reservoirs, Potomac River, Groundwater and surface water, Potomac River via WSSC, Potomac River via WSSC and Patuxent.
- EPA Safe Drinking Water Information System
- EWG Tap Water Database
- State utility Consumer Confidence Reports
- USGS regional water monitoring data
PurityMap compiles publicly available data and does not perform independent testing.
6 city water quality reports available for Maryland.
Baltimore Water Quality Report
Bowie Water Quality Report
Frederick Water Quality Report
Gaithersburg Water Quality Report
Rockville Water Quality Report
Compare water quality reports across all 50 US states