Hard water in Idaho Falls, ID

Tap water hardness
173mg/L
10.1gpg
Hard

Reported by Idaho Falls City of · April 2025

ID typical
118 mg/L
EPA health violations since 2016
0
Softener for 3 people
24k grain
Data
Utility report

Tap water in Idaho Falls has about 173 mg/L of hardness, which is 10.1 grains per gallon. On the USGS scale that counts as hard. The number comes from Idaho Falls City of, dated April 2025.

Idaho Falls on the hardness scale, with nearby cities
060120180240300360+ID typical 118Rexburg: 72 mg/LRexburg 72Meridian: 86 mg/LMeridian 86Boise City: 90 mg/LBoise City 90Garden City: 90 mg/LGarden City 90Kuna: 90 mg/LKuna 90Eagle: 90 mg/LEagle 90Blackfoot: 119 mg/LBlackfoot 119Chubbuck: 340 mg/LChubbuck 340Pocatello: 351 mg/LPocatello 351Twin Falls: 400 mg/LTwin Falls 400Idaho Falls 173mg/L as calcium carbonate060120180240300360+ID 118Rexburg: 72 mg/LRexburg 72Boise City: 90 mg/LBoise City 90Blackfoot: 119 mg/LBlackfoot 119Chubbuck: 340 mg/LChubbuck 340Pocatello: 351 mg/LPocatello 351Twin Falls: 400 mg/LTwin Falls 400173 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

Idaho Falls sits 55 mg/L above the typical Idaho figure of 118. Of the 10 nearest cities we track, 7 have softer water and 3 have harder. The range nearby runs from 72 mg/L in Rexburg to 400 in Twin Falls.

What 173 mg/L means at home

Expect white crust on faucets and showerheads, plus spots on dishes that come out of the dishwasher.

Kettles collect scale quickly. Water heaters build up sediment at the bottom of the tank, which makes them work harder over time.

Soap and detergent need a little more to lather, and soap scum shows up in the tub.

Hardness is not a health problem, and EPA sets no limit for it. It is a matter of scale and soap.

What to do about it

At 173 mg/L most of the trouble is scale, and only a few things deal with it.

Ion-exchange water softener

The standard whole-house fix. It swaps calcium and magnesium for sodium or potassium and needs salt plus a drain. Size it with the calculator below.

Salt-free conditioner

No salt and no drain line. It changes how minerals form scale instead of removing them, so water still tests hard.

Reverse osmosis or carbon filter

Under-sink reverse osmosis removes minerals from drinking water only. Plain carbon filters improve taste but do not soften.

Softener size for Idaho Falls

3 people × 75 gallons a day × 10.1 gpg = 2,277 grains a day. A 24,000-grain unit regenerates about every 10 days.

Size it for your household

EPA record for Idaho Falls's water system

Idaho Falls City of · PWSID ID7100039

No health-based violations since 2016

Serves about 69,450 people from groundwater.

Health-based
0
Monitoring or reporting
6
Open now
0

Health-based means a contaminant above its legal limit or a missed treatment step. Monitoring and reporting violations are late or missing tests and notices. Source: EPA ECHO, 2026Q3 export, violations with periods starting 2016 or later. Full EPA record.

Questions

Is Idaho Falls water hard?

Yes. It measures about 173 mg/L (10.1 grains per gallon), which the USGS classes as hard.

What is the water hardness in Idaho Falls in grains per gallon?

About 10.1 gpg. One grain per gallon equals 17.1 mg/L, so 173 mg/L divided by 17.1 gives 10.1.

What size water softener do I need in Idaho Falls?

For 3 people using 75 gallons each per day, 10.1 gpg works out to about 2,277 grains a day. A 24,000-grain softener covers that with a regeneration about every 10 days.

Has the Idaho Falls water system had EPA violations?

EPA records show no health-based violations for Idaho Falls City of since 2016. There were also 6 monitoring or reporting violations, which are about late or missing tests and notices.

Nearby cities

All 21 cities in Idaho

Hardness data: TapWaterData US Water Hardness (utility report, April 2, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.