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Not health advice. Contact your local water utility for concerns.
Data from EPA Water Quality Reports. For official information, contact your water utility or health department.
Water quality scores for 20 cities in Idaho
Across the 20 Idaho water systems we track, the average water quality score is 78/100 — 6 points above the U.S. national average of 72/100. 60% of Idaho cities (12 of 20) score above that national benchmark, and 6 earn a Grade A for clean, low-contaminant tap water.
The contaminants most commonly flagged in Idaho water systems are nitrates (irrigated agriculture), arsenic (naturally occurring in groundwater) and heavy metals (northern mining legacy). See the full breakdown in our Idaho water quality rankings or compare against the cities with the best water quality in America.
See the top 20 cities with the cleanest, safest drinking water
Complete water quality rankings for every city in Idaho
54,628 residents
31,441 residents
56,320 residents
38,485 residents
15,570 residents
14,308 residents
59,996 residents
235,684 residents
26,047 residents
64,818 residents
12,137 residents
51,807 residents
100,200 residents
12,329 residents
24,011 residents
34,203 residents
17,694 residents
117,635 residents
12,346 residents
31,384 residents
Idaho's water quality is generally good, fed by mountain snowmelt and large aquifer systems, but the state faces localized issues from agriculture, mining legacy in the north, and naturally occurring contaminants. The vast Eastern Snake River Plain Aquifer is one of the most productive in the country and supplies much of southern Idaho.
Based on our analysis of 20 cities in Idaho, the average water quality score is 78/100. 3 cities have water quality scores below 70, indicating potential concerns that residents should be aware of. The highest-rated city is Eagle with a score of 66/100, while Coeur d'Alene has the most room for improvement at 95/100.
3 of the 20 Idaho cities we analyzed score below 70/100. If your city is one of them, a certified filter matched to your local contaminants is the fastest way to reduce exposure. For lead and PFAS, look for an NSF 53 certified filter or a reverse osmosis system.
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Southern Idaho relies heavily on the Eastern Snake River Plain Aquifer and the Snake River, supporting both drinking water and extensive irrigation. Boise draws from the Boise River and groundwater. Northern Idaho communities use mountain surface water and aquifers, some affected by the historic Silver Valley mining district.
These contaminants have been detected in various Idaho water systems
The Idaho Department of Environmental Quality (DEQ) administers the Safe Drinking Water Act and oversees source water protection. Idaho monitors nitrate trends in heavily irrigated areas and coordinates on cleanup of the Bunker Hill Superfund site in the Silver Valley.
Nitrate from irrigation and dairies is a concern in the Magic Valley and other agricultural areas, especially for private wells. Naturally occurring arsenic affects some groundwater systems statewide. In the Silver Valley region, legacy mining contamination requires ongoing management.
Idaho private-well owners should test for nitrate, arsenic, and bacteria, particularly in irrigated regions. Reverse osmosis removes nitrate, arsenic, and uranium effectively. Municipal customers generally enjoy good water but should review their Consumer Confidence Report and address any lead plumbing in older homes.
Water quality in Idaho varies by location. Our analysis shows an average score of 78/100 across 20 cities, with 3 cities showing potential concerns. We recommend checking your specific city's water quality report and considering filtration if needed.
The most common water quality concerns in Idaho include nitrates (irrigated agriculture), arsenic (naturally occurring in groundwater), heavy metals (northern mining legacy). These contaminants can come from natural sources, industrial activities, or aging infrastructure. Review your city's specific report to see which contaminants affect your area.
Whether you need a water filter depends on your specific location and health concerns. With 3 cities in Idaho showing elevated contaminant levels, residents in those areas may benefit from filtration. Look for filters certified by NSF/ANSI to remove the specific contaminants found in your area.
Public water systems in Idaho are required to provide annual Consumer Confidence Reports (CCRs) to residents. You can usually find your report on your water utility's website, request it by phone, or access it through the EPA's database. Our city-level reports above summarize key information from these official sources.
Lead can be present in Idaho water, primarily from older plumbing infrastructure. Homes built before 1986 may have lead pipes or lead solder. While water treatment plants remove lead, it can leach into water from service lines and home plumbing. Check your city's specific report for lead testing data, and consider having your tap water tested if you live in an older home.
PFAS ("forever chemicals") have been detected in water systems across the United States, including in Idaho. These chemicals are associated with industrial sites, military bases, and firefighting foam use. The EPA has set new PFAS limits effective 2024. Check individual Idaho city reports for PFAS testing results in your area.
Based on our analysis, Eagle has the highest water quality score in Idaho at 66/100 (Grade C+). However, "best" depends on your specific health concerns. View our Best Water Quality in Idaho page for a complete ranking.
Public water systems in Idaho are required by the EPA to test water regularly. Testing frequency depends on the contaminant: bacteria testing occurs daily to weekly, while chemical contaminants may be tested quarterly or annually. Results are published in annual Consumer Confidence Reports. Our site aggregates this data from EPA's SDWIS database.
Compare water quality across counties and find data for your area