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National Drinking Water Database

National Drinking Water Database - Chemical Contaminants

The Most Polluted Communities

2 water utilities reported detecting Iodine-131 in tap water since 2004, according to EWG's analysis of water quality data supplied by state water agencies

Ranked by highest average Iodine-131 level

RankSystem Population Served Positive test results of total reported tests Average Level
1Clark Public Utilities
Vancouver, WA
79,9481 of 1545000 ppb
(545000 ppb)
2City of Kennewick
Kennewick, WA
64,6801 of 3334.44 ppb
(0 to 1003.33 ppb)