Radon in Maryland well water
In Maryland, radon was detected in 96% of 852 tested private well samples.
Radon is a radioactive gas released from bedrock into well water. It escapes into household air during showers and washing, where inhaling it raises lung cancer risk. EPA has no enforceable water MCL; New Hampshire recommends treatment above 2,000 pCi/L, and many states use 4,000 pCi/L.
Check your radon number
Type the value from your lab report. It is compared to the EPA limit, the same way the full interpretation does it.
Test your Maryland well for radon
Certified lab analysis of your own tap water, bottles and prepaid return shipping included. The Essential well panel covers arsenic, uranium, nitrate, lead, copper, manganese, iron, sodium and bacteria; radon and PFAS are add-ons.
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Getting it fixed
Book a free in-home water test with a licensed local company, or see the treatment guide for what removes radon.
Where to get a well tested for radon in Maryland: certified labs, state programs and prices.
By county, from individual samples
Public monitoring samples against the EPA limit; counties with at least 30 samples.
| County | Above EPA limit | Samples | Detected | Median | Highest |
|---|---|---|---|---|---|
| Baltimore | no limit | 180 | 99% | 2,445 | 28,600 pCi/L |
| Howard | no limit | 107 | 99% | 3,400 | 42,000 pCi/L |
| Anne Arundel | no limit | 81 | 99% | 230 | 990 pCi/L |
| Queen Anne's | no limit | 41 | 98% | 240 | 2,400 pCi/L |
| Caroline | no limit | 35 | 97% | 280 | 1,300 pCi/L |
| Kent | no limit | 95 | 96% | 350 | 1,400 pCi/L |
| Garrett | no limit | 44 | 95% | 167 | 6,400 pCi/L |
- District 5, Baltimore County100% detected of 30
- District 7, Baltimore County100% detected of 34
- District 4, Lisbon, Howard County100% detected of 30
- District 2, Kennedyville, Kent County93% detected of 46
Sources
- Individual samples from the USGS Water Quality Portal and state monitoring, summarized per geography. radon counts and shares are listed on each county and town page with their sources.