Your county health department
Maryland doesn't run a statewide free testing program that we know of. Some county health departments test wells or sell kits, so call yours first.
Maryland's private well pageArsenic in Maryland well water, by county
Arsenic is widespread, over the limit in 15% or more of tested wells, in 3 of the 16 Maryland counties with 10 or more tested wells. A county's share tells you how likely a problem is nearby. Only a test of your own well tells you what's in it.
How Maryland compares with the rest of the country
Across Maryland, about 1 in 12 tested wells had arsenic over the EPA limit of 10 µg/L (33 of 411). Across all tested wells in the US it's about 1 in 9. That's less often than in the country as a whole. Counties still differ, so check yours below.
Why it matters: Drinking it for years raises the risk of skin, bladder and lung cancer.
Arsenic dissolves out of certain rocks and old sediments, so it can be high even where nobody has polluted anything.
Arsenic in tested wells, county by county
Share of each county's tested wells with at least one result over the EPA limit of 10 µg/L. Counties need 10 or more tested wells to be listed. Widespread means 15% or more, worth checking 5 to 15%, rare under 5%.
| County | Wells tested | Wells over the limit | Level |
|---|---|---|---|
| Dorchester County | 19 | Widespread | |
| Kent County | 10 | Widespread | |
| Talbot County | 13 | Widespread | |
| St. Mary's County | 25 | Worth checking | |
| Garrett County | 70 | Worth checking | |
| Queen Anne's County | 36 | Worth checking | |
| Carroll County | 11 | Worth checking | |
| Cecil County | 14 | Worth checking | |
| Anne Arundel County | 47 | Worth checking | |
| Caroline County | 24 | Rare | |
| Montgomery County | 22 | Rare | |
| Charles County | 18 | Rare | |
| Washington County | 15 | Rare | |
| Frederick County | 14 | Rare | |
| Calvert County | 10 | Rare | |
| Worcester County | 10 | Rare |
7 more Maryland counties have 1 to 9 tested wells for arsenic, too few to rate.
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Where to get your well tested for arsenic in Maryland
A lab Maryland certifies
Ask for arsenic by name. Results from a certified lab count for a home sale or a loan.
Labs certified by Maryland (PDF)A mail-in kit
Fill the bottles at your kitchen tap and mail them back. We mark the kits that include arsenic.
Compare kitsKeep reading about wells in Maryland
- Well water testing in Maryland: how to get tested and what turns up statewide
- Arsenic in well water: where it comes from, what it does and how to remove it
- Nitrate in Maryland wells, by county
- Uranium in Maryland wells, by county
- Manganese in Maryland wells, by county
- Lead in Maryland wells, by county
- Radon in Maryland wells, by county
Questions people ask about arsenic in Maryland
Is there arsenic in Maryland well water?
Arsenic is widespread, over the limit in 15% or more of tested wells, in 3 of the 16 Maryland counties with 10 or more tested wells. Across Maryland, about 1 in 12 tested wells had arsenic over the EPA limit of 10 µg/L (33 of 411). Across all tested wells in the US it's about 1 in 9. That's less often than in the country as a whole. Counties still differ, so check yours below.
Where can I get my well tested for arsenic in Maryland?
Use a lab certified by Maryland for drinking water, or a mail-in kit that includes arsenic from a certified lab. Some county health departments test wells too, so call yours first.
See Maryland's list of certified labs (a PDF list), or compare mail-in kits.
Where these numbers come from
- Lab tests: Water Quality Portal (USGS and EPA), well samples since 2000. A well counts as over if any of its tests was over the EPA limit of 10 µg/L. Wells tested for studies and monitoring, not a random sample of homes.
- Likely overstated: our own check of who tested the wells, when and where. How we check.
- State programs and links: Maryland Department of the Environment.