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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
126–150 of 174City of Greenleaf
ID3140041 · 846 served
Kootenai County Water Dist 1
ID1280106 · 843 served
Gem State - Spirit Lake East
ID1280176 · 843 served
E Shoshone County Water Dist Mullan
ID1400017 · 840 served
City of Oakley
ID5160035 · 821 served
City of Potlatch
ID2290030 · 812 served
Meadow Creek Property Owners Assn Inc
ID3020009 · 800 served
Hillsdale Estates Homeowners Assn
ID4010218 · 800 served
City of Mccammon
ID6030038 · 800 served
City of Inkom
ID6030025 · 792 served
Horseshoe Bend Water Supply
ID4080024 · 750 served
City of Teton
ID7220072 · 735 served
City of Clark Fork
ID1090018 · 730 served
Sagle Valley Water Dist
ID1090118 · 708 served
City of Roberts
ID7260035 · 680 served
3d Water Association
ID7100201 · 680 served
Cataldo Water Dist
ID1400012 · 680 served
Laclede Water Dist
ID1090073 · 668 served
City of Ririe
ID7260034 · 656 served
Desert View Estates Water Corp
ID4010042 · 650 served
City of Melba
ID3140070 · 648 served
Gem State - Bar Circle S Ranch
ID1280010 · 633 served
City of Downey
ID6030012 · 625 served
City of Juliaetta
ID2290018 · 624 served
Southside Water and Sewer Dist
ID1090131 · 615 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