Copper in Maryland Drinking Water
Ranked by 90th percentile copper level (mg/L) · Data from EPA SDWIS & UCMR
Copper in Maryland: what the data shows
Maryland has 29 cities with copper monitoring data. The state average 90th percentile copper level is 2.146 mg/L, compared to 28.808 mg/L nationally — better than the national average. 29 cities exceed the EPA action level of 1.3 mg/L. Copper in drinking water typically comes from corrosion of copper pipes and plumbing fixtures, particularly in older homes. The EPA action level of 1.3 mg/L is the 90th percentile threshold — if more than 10% of tap samples exceed it, utilities must take corrective action including adjusting water chemistry to reduce corrosivity. Short-term copper exposure above the action level can cause gastrointestinal distress. Long-term exposure at elevated levels is associated with liver and kidney damage. Flushing your tap for 30 seconds before use and using an NSF 53-certified filter can reduce copper exposure.
Cities exceeding 1.3 mg/L EPA Action Level
Copper data across Maryland
Each dot is a city, colored by overall water quality grade. Cities with copper levels above the 1.3 mg/L EPA action level are highlighted. Size reflects population served.
Top 10 cities by copper level in Maryland
Highest Copper levels (mg/L)
All Maryland cities ranked by copper level
| # | City | Level | Level | Exceeds? | Violations | Grade |
|---|---|---|---|---|---|---|
| 1 | Delmar | 5.130 mg/L | Yes | 13 | B+ | |
| 2 | Salisbury | 4.310 mg/L | Yes | 26 | F | |
| 3 | Hebron | 4.200 mg/L | Yes | 28 | A- | |
| 4 | Berlin | 3.440 mg/L | Yes | 6 | D | |
| 5 | Smithsburg | 3.200 mg/L | Yes | 19 | B | |
| 6 | Manchester | 2.600 mg/L | Yes | 4 | B+ | |
| 7 | Lonaconing | 2.200 mg/L | Yes | 9 | C+ | |
| 8 | Severn | 2.080 mg/L | Yes | 3 | B- | |
| 9 | Baltimore | 2.076 mg/L | Yes | 12 | F | |
| 10 | Oakland | 2.000 mg/L | Yes | 80 | C+ | |
| 11 | Hagerstown | 1.980 mg/L | Yes | 42 | C | |
| 12 | Frederick | 1.960 mg/L | Yes | 18 | F | |
| 13 | Timonium | 1.940 mg/L | Yes | 3 | B+ | |
| 14 | Ridgely | 1.900 mg/L | Yes | 5 | B- | |
| 15 | Ellicott City | 1.780 mg/L | Yes | 56 | D | |
| 16 | Grasonville | 1.765 mg/L | Yes | 2 | B- | |
| 17 | Hampstead | 1.660 mg/L | Yes | 2 | B+ | |
| 18 | Emmitsburg | 1.640 mg/L | Yes | 44 | B | |
| 19 | Cumberland | 1.630 mg/L | Yes | 4 | B+ | |
| 20 | Elkton | 1.600 mg/L | Yes | 42 | F | |
| 21 | Mount Airy | 1.600 mg/L | Yes | 4 | C+ | |
| 22 | Street | 1.600 mg/L | Yes | 2 | B- | |
| 23 | North East | 1.497 mg/L | Yes | 95 | F | |
| 24 | Stevensville | 1.490 mg/L | Yes | 6 | C | |
| 25 | Port Deposit | 1.420 mg/L | Yes | 31 | F | |
| 26 | Fruitland | 1.400 mg/L | Yes | 14 | C+ | |
| 27 | Dunkirk | 1.390 mg/L | Yes | 1 | A- | |
| 28 | Lavale | 1.390 mg/L | Yes | 3 | B | |
| 29 | Hancock | 1.370 mg/L | Yes | 2 | B |
Frequently asked questions about copper in Maryland
Is copper in Maryland drinking water safe?
29 cities in Maryland exceed the EPA action level of 1.3 mg/L for copper. The state average is 2.146 mg/L. Copper levels are highest in homes with copper plumbing, particularly when water sits in pipes overnight. Flushing the tap before use significantly reduces copper in drinking water.
What causes high copper levels in Maryland tap water?
Copper typically leaches from copper pipes and brass fittings within homes, not from the water source itself. Corrosive (low pH or soft) water accelerates this leaching. Water utilities with high copper readings are required to adjust water chemistry to reduce corrosivity. You can reduce exposure by flushing your tap for 30 seconds before use.