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Idaho Water Quality
174
Utilities in database
1.5M
Residents served
40%
On private wells
2
Key contaminants tracked
Drinking Water in Idaho
Idaho has 174 community water systems serving approximately 1.5 million residents. Primary water sources include groundwater. The most commonly reported contaminants include arsenic, nitrates. 40% of Idaho residents rely on private wells. DEQ holds primary enforcement authority under the Safe Drinking Water Act.
Utilities in Idaho
1–25 of 174Veolia Water Idaho
ID4010016 · 264,978 served
Meridian Water Dept
ID4010097 · 147,340 served
City of Nampa
ID3140080 · 100,200 served
City of Caldwell
ID3140013 · 74,000 served
City of Idaho Falls
ID7100039 · 69,450 served
City of Pocatello
ID6030043 · 58,231 served
City of Twin Falls
ID5420058 · 56,121 served
City of Coeur D Alene
ID1280053 · 54,115 served
City of Rexburg
ID7330022 · 39,790 served
City of Kuna
ID4010085 · 32,038 served
Moscow Water Dept
ID2290023 · 26,000 served
Falls Water Company Inc
ID7100030 · 22,650 served
City of Post Falls
ID1280147 · 20,285 served
Lewiston Orchards Irrigation Dist
ID2350015 · 20,000 served
City of Ammon
ID7100004 · 17,338 served
City of Chubbuck
ID6030008 · 15,842 served
City of Lewiston
ID2350014 · 15,001 served
City of Mountain Home
ID4200032 · 14,651 served
Star Sewer and Water Dist Water System
ID4010220 · 14,000 served
City of Blackfoot
ID6060007 · 13,224 served
City of Middleton
ID3140074 · 13,190 served
City of Jerome
ID5270011 · 13,135 served
Garden City Water and Sewer System
ID4010066 · 12,500 served
Sandpoint Public Works Dept
ID1090121 · 12,284 served
East Greenacres Irrigation Dist
ID1280064 · 11,165 served
Key Contaminant Concerns in Idaho
Nitrates
Nitrate (NO₃⁻) is a nitrogen-containing compound that forms naturally through the decomposition of organic matter. At elevated concentrations — almost always from human activity — nitrate interferes with the blood's ability to carry oxygen. The United States produces over 23 million tons of nitrogen fertilizer annually, making agricultural runoff the dominant source of nitrate contamination.
Arsenic
Arsenic (As) occurs naturally in rock and soil, dissolving into groundwater through natural weathering processes. Inorganic arsenic — the form found in drinking water — is a known human carcinogen. The western United States has particularly arsenic-rich geological formations, but elevated levels have been found in 48 states. Arsenic is tasteless and odorless.
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Data source: Utility data from EPA SDWIS. 174 active community water systems ingested. CCR contaminant data ingestion in progress.
Last updated: 2026-04-22