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Radon

Status: No national drinking water standard exists

 

Radon is a radioactive gas that comes from soil and groundwater, and causes lung cancer. Highest exposures come from radon entering a house through its basement or crawl spaces, or from it volatilizing in the water. Read More.

Radon is the most common source of radiation exposure in the home. Radon in tap water is a smaller source of exposure compared to radon in indoor air. Water utilities report radon in picocuries per liter (pCi/L), which is a measure of radioactivity in water. The federal government has not set a Maximum Contaminant Level (MCL) for radon in tap water. In 1991, the EPA proposed a drinking water standard of 300 picocuries per liter for radon, which was not finalized. In 1999, the EPA proposed a combined approach for reducing radon risk in indoor air and limiting radon in drinking water. This approach recommended a maximum of 4,000 picocuries of radon per liter of drinking water in states with programs to address radon air risks. Where there was no state program for radon mitigation, a water radon limit of 300 picocuries per liter was to apply. This proposal has not yet become a federal law.

Click here to read more on radiological contaminants.

The draft federal limits for radon do not sufficiently protect public health. The EPA's analysis on radon cancer risk suggests that for a water limit of 300 picocuries per liter, 200 in every 1 million people drinking water with this much radon could develop cancer over their lifetimes. For a water limit of 4000 picocuries per liter, over 2,000 people in every 1 million could develop cancer over their lifetimes. The EPA estimates that radon in drinking water causes about 168 cancer deaths per year - nearly 90 percent of which come from lung cancer caused by breathing radon released from water during showering or other water use. The remainder of cancer deaths are primarily from stomach cancer caused by consuming radon in water.

2010-2015:

FOUND
FOUND ABOVE HEALTH GUIDELINES

22

states detected

454

utilities detected

8.7 million

people served

22

states over health guideline

454

utilities over health guideline

8.7 million

people served over health guideline

Health concerns for radon

Lung cancer

Stomach cancer

State and national drinking water standards and health guidelines

Health Guideline 1.5 pCi/L

The health guideline of 1.5 pCi/L for radon was defined by the Environmental Protection Agency as a one-in-a-million lifetime risk of cancer. Values greater than one-in-a-million cancer risk level can result in increased cancer cases above one in a million people.

pCi/L = picocuries per liter.

States reporting radon in drinking water

UTILITIES REPORTING ABOVE HEALTH GUIDELINES UTILITIES WITH CONTAMINATION
State UtilitiesPeople Served UtilitiesPeople Served
California974,664,349974,664,349
Arizona72,296,76372,296,763
Washington10284,98710284,987
Colorado14261,57914261,579
Nevada52178,37052178,370
Massachusetts42160,54342160,543
Maine54131,59654131,596
Wisconsin36120,81736120,817
Minnesota19108,44419108,444
Missouri791,044791,044
Kansas3480,3093480,309
North Carolina1166,0011166,001
Utah364,437364,437
Maryland2254,0992254,099
Oregon245,084245,084
New York2538,8872538,887
Alabama438,685438,685
Rhode Island338,178338,178
Nebraska29,39329,393
Virginia51,53951,539
Georgia12911291
Vermont42134213
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Utilities with the highest amounts of radon, 2010-2015

ALL UTILITIES
LARGE UTILITIES
UtilityLocationTestsAverage levelPeople served
Buffumville Heights Estates CondominiumOxford, MA18 of 1833,645.56 pCi/L40
Staffordshire Country EstatesLeicester, MA21 of 2125,042.57 pCi/L140
Northeastern EstatesStandish, ME4 of 423,935.00 pCi/L40
Northern Spring ParkPoland, ME7 of 819,735.88 pCi/L90
Meadow View Trailer CourtPelham, NC1 of 118,286.00 pCi/L81
Abbotsford WaterworksAbbotsford, WI2 of 213,777.50 pCi/L1,956
Pinewood On The Green CondosOxford, MA16 of 1812,657.22 pCi/L50
Fcwwd #40/shaver SpringsFresno, CA2 of 212,440.00 pCi/L69
Poland Place Condo AssociationPoland, ME4 of 412,018.50 pCi/L35
Colby WaterworksColby, WI1 of 110,819.00 pCi/L1,751
Cherry Valley/ Rochdale Water DistrictLeicester, MA19 of 2010,804.00 pCi/L3,332
Harriman VillageHarriman, NY6 of 69,921.30 pCi/L5,000
Charlton Manor Rest HomeCharlton, MA10 of 119,882.73 pCi/L26
Pinewood Acres Trailer ParkBowdoin, ME9 of 98,305.22 pCi/L63
Rockwood MeadowsUpton, MA6 of 67,475.00 pCi/L124
Benchmark CondominiumsTyngsborough, MA13 of 187,155.56 pCi/L180
Ayer Road Properties LLCHarvard, MA27 of 296,557.97 pCi/L150
Brook HollowPortland, ME7 of 76,083.57 pCi/L30
Lightning WReno, NV4 of 45,686.80 pCi/L163
Rio WaterworksRio, WI1 of 15,600.00 pCi/L1,058
Estates At Highland RidgeHopkinton, MA13 of 145,445.71 pCi/L100
Lamoille Water Users AssociationLamoille, NV3 of 35,332.83 pCi/L200
Charter Oak Mobile Home VillageFlagstaff, ME4 of 44,790.00 pCi/L105
Village At Highland ParkHopkinton, MA2 of 24,750.00 pCi/L50
Chimera Inc.Chepachet, RI1 of 14,600.00 pCi/L133
Sunset Ridge CondominiumsBolton, MA9 of 123,768.33 pCi/L42
Northern Bay Residential Living CenterChester, ME1 of 13,480.00 pCi/L150
Canton Water DistrictCanton, ME1 of 13,392.00 pCi/L293
Nezinscot VillageAuburn, ME1 of 13,380.00 pCi/L40
New Gloucester Water DistrictNew Gloucester, ME5 of 53,262.20 pCi/L130
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UtilityLocationTestsAverage levelPeople served
Marshfield UtilitiesMarshfield, WI1 of 11,700.00 pCi/L18,708
Holliston Water DepartmentHolliston, MA3 of 31,533.33 pCi/L14,946
Westerly Water DepartmentWesterly, RI3 of 31,527.67 pCi/L38,000
Kennebunk, Kennebunkport & Wells WD*Kennebunk, ME1 of 11,150.00 pCi/L31,440
Maynard DPW, Water DivisionMaynard, MA5 of 9955.56 pCi/L10,314
Greater Augusta Utility District*Augusta, ME4 of 4923.75 pCi/L14,380
Centennial Water and Sanitation District*Highlands Ranch, CO6 of 9680.22 pCi/L88,042
Dayton Valley Water System*Dayton, NV4 of 4662.98 pCi/L14,168
Cherokee MD*Colorado Springs, CO1 of 1660.00 pCi/L20,600
City of ElkoElko, NV9 of 9656.63 pCi/L18,000
Grafton Water District*Grafton, MA2 of 3643.33 pCi/L10,703
South Tahoe PUD - Main*South Lake Tahoe, CA71 of 73637.84 pCi/L29,500
City of Tualatin*Tualatin, OR1 of 1601.00 pCi/L26,879
Golden State WC - PlacentiaAnaheim, CA1 of 1557.00 pCi/L36,374
Elk Grove Water ServiceElk Grove, CA1 of 1543.00 pCi/L40,461
Lompoc Water Utility DivisionLompoc, CA1 of 1525.00 pCi/L39,846
Sacramento Suburban Water District*Sacramento, CA1 of 1525.00 pCi/L171,200
City of Santa Barbara Water Department*Santa Barbara, CA15 of 16513.75 pCi/L92,371
City of Riverside*Riverside, CA5 of 5488.00 pCi/L303,871
City of StocktonLodi, CA1 of 1447.00 pCi/L171,687
City of Spokane*Spokane, WA2 of 2404.50 pCi/L227,505
City of Mesa*Mesa, AZ50 of 54368.70 pCi/L466,000
City of AnaheimAnaheim, CA8 of 8338.75 pCi/L450,000
City of Seal BeachSeal Beach, CA4 of 4333.00 pCi/L24,157
Mesa Water DistrictCosta Mesa, CA1 of 1323.00 pCi/L108,000
South Davis Water District*Salt Lake City, UT7 of 7320.29 pCi/L10,637
City of Junction City*Junction City, KS1 of 1320.00 pCi/L24,665
Elk RiverElk River, MN2 of 2294.00 pCi/L22,974
Fernley Public WorksFernley, NV2 of 2293.55 pCi/L18,000
City of Fountain ValleyFountain Valley, CA15 of 15284.67 pCi/L56,464

* This water utility supplies finished drinking water to at least one other water utility. The purchasing utility is not required to test for or report Radon, but it likely has the contaminant in its water supply.

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