Is Idaho Tap Water Safe to Drink?
Water quality data for 11 cities across Idaho. Find your city below.
Water quality in Idaho varies significantly from city to city. Across 11 cities we track, hardness ranges from 25 PPM in Coeur d'Alene to 140 PPM in Twin Falls, with a statewide average of 73 PPM. 1 of 11 cities have hard water above 120 PPM where a water softener provides measurable benefits.
1 Idaho cities have forever chemicals (PFAS) above the EPA's 2024 limit of 4 parts per trillion: Meridian (8.3 ppt). A reverse osmosis system or NSF P473-certified filter can reduce PFAS to safe levels.
Complete Idaho Guide
Statewide water quality overview, costs, and treatment recommendations.
Well Water in Idaho
Testing, treatment, and common issues for private wells.
Hardest Water Rankings
Idaho cities ranked by water hardness level.
City Comparisons
Twin Falls vs Coeur D Alene
Side-by-side water quality comparison.
Twin Falls vs Boise
Side-by-side water quality comparison.
Boise vs Idaho Falls
Side-by-side water quality comparison.
Idaho Cities by Water Hardness
| City | Hardness (PPM) | Level | PFAS (ppt) | Source |
|---|---|---|---|---|
| Twin Falls | 140 | Hard | 0 | Blue Lakes Spring & Snake River |
| Boise | 110 | Moderately Hard | 0 | Boise River + groundwater |
| Idaho Falls | 91 | Moderately Hard | 0 | Snake River |
| Pocatello | 86 | Moderately Hard | 0 | Groundwater wells |
| Meridian | 82 | Moderately Hard | 8.3 | Groundwater wells |
| Caldwell | 70 | Moderately Hard | 0 | Surface water via Canyon County |
| Nampa | 62 | Moderately Hard | 0 | Snake River, groundwater |
| Eagle | 55 | Slightly Hard | 0 | Local wells |
| Boise Downtown | 50 | Slightly Hard | 0 | Boise River + wells |
| Lewiston | 35 | Slightly Hard | 0 | Clearwater River & wells |
| Coeur d'Alene | 25 | Slightly Hard | 0 | Coeur d'Alene Lake & Rathdrum Prairi… |