Post Falls Water Hardness & Quality Report (2026)
Water Hardness
2.7 grains per gallon
Source
reservoir
pH Level
7.3
neutral = 7.0
Lead
0.003 mg/L
✓ Below action level
TDS
81 mg/L
Est. Daily Cost
$0.12
energy & soap waste
Source: USGS Water Quality Portal · Updated 2026
0–60
mg/L
Soft
61–120
mg/L
Moderately Hard
121–180
mg/L
Hard
180+
mg/L
Very Hard
Appliance Damage Report
In Post Falls, your appliances are currently losing 6% efficiency due to mineral buildup.
| Appliance | In Post Falls | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 8.1 yrs | 8.5 yrs | -5% |
| Washing Machine | 11.9 yrs | 12 yrs | -1% |
| Water Heater | 13.8 yrs | 15 yrs | -8% |
Regional Water Comparison
How Post Falls compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Post Falls, Idaho | 46 mg/L | 1.3 ppt | 🟢 Soft | reservoir |
| Hayden, Idaho | 104 mg/L | 2.2 ppt | 🟡 Moderately Hard | reservoir |
| Coeur d'Alene, Idaho | 60 mg/L | 1.5 ppt | 🟡 Moderately Hard | reservoir |
| Spokane Valley, Washington | 55.5 mg/L | 2.5 ppt | 🟢 Soft | reservoir |
| Opportunity, Washington | 35 mg/L | 1.9 ppt | 🟢 Soft | reservoir |
National Benchmark
How Post Falls compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Post Falls | 46 mg/L | 🟢 None |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Post Falls's Water Unique?
Local geology and source profile
Post Falls, Idaho, in Kootenai County — a major north Idaho Coeur d'Alene suburban community (Post Falls is a significant Kootenai County city — the second-largest city in the Coeur d'Alene metro area (the Coeur d'Alene–Post Falls corridor is the second-largest urban area in Idaho after Boise–Nampa); Post Falls has been one of Idaho's fastest-growing cities, driven by its location on the Spokane River between Coeur d'Alene and the Washington state border), home of the Post Falls Dam and the Spokane River corridor (one of the most scenic river recreation areas in north Idaho), a diverse Kootenai County community with a primarily working-class, manufacturing, and suburban family population, adjacent to Coeur d'Alene in the Kootenai County corridor, and a community with significant outdoor recreation access (Spokane River rafting and fishing are popular Post Falls activities) — draws its municipal water supply from the Rathdrum Prairie Aquifer via the City of Post Falls Water Division. Water hardness in Post Falls measures 46 mg/L — classified as very soft.
Post Falls's very soft supply reflects the Kootenai County Rathdrum Prairie glacial aquifer's calcareous-poor character. The Rathdrum Prairie Aquifer draws from Quaternary calcareous-poor glacial outwash from the Precambrian Idaho Selkirk Mountains granite (calcareous-poor). City of Post Falls produces the very soft 46 mg/L.
With hardness at 46 mg/L, Post Falls residents enjoy very soft water. City of Post Falls Water Division consistently delivers water meeting all Idaho DEQ and EPA Safe Drinking Water Act requirements.
Geology & Source: Groundwater from the Rathdrum Prairie Aquifer (Lake Spokane watershed) via the City of Post Falls Water Division — the Kootenai County north Idaho Coeur d'Alene–Spokane corridor (Precambrian calcareous-poor Idaho Selkirk Ranges granite and Quaternary calcareous-poor glacial outwash — the extremely calcareous-poor north Idaho Rathdrum Prairie glacial aquifer); very soft supply at 46 mg/L in Kootenai County.