Hard water in Pocatello, ID

Tap water hardness
351mg/L
20.5gpg
Very hard

Reported by Pocatello City of · January 2025

ID typical
118 mg/L
EPA health violations since 2016
1
Softener for 3 people
48k grain
Data
Utility report

Tap water in Pocatello has about 351 mg/L of hardness, which is 20.5 grains per gallon. On the USGS scale that counts as very hard. The number comes from Pocatello City of, dated January 2025.

Pocatello 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 119Idaho Falls: 173 mg/LIdaho Falls 173Chubbuck: 340 mg/LChubbuck 340Twin Falls: 400 mg/LTwin Falls 400Pocatello 351mg/L as calcium carbonate060120180240300360+ID 118Rexburg: 72 mg/LRexburg 72Boise City: 90 mg/LBoise City 90Blackfoot: 119 mg/LBlackfoot 119Idaho Falls: 173 mg/LIdaho Falls 173Chubbuck: 340 mg/LChubbuck 340Twin Falls: 400 mg/LTwin Falls 400351 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

At 351 mg/L, Pocatello is 233 mg/L above the typical Idaho figure of 118. Of the 10 nearest cities we track, 9 have softer water and 1 has harder. The range nearby runs from 72 mg/L in Rexburg to 400 in Twin Falls.

What 351 mg/L means at home

Scale forms fast here. Kettles and coffee makers need regular descaling, and showerheads clog unless you clean them.

Tank water heaters collect mineral sediment that insulates the water from the burner, so flushing the tank matters more than usual.

Dishes and glass shower doors spot easily. Soap scum and a dull film on hair or laundry are common complaints.

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 351 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 Pocatello

3 people × 75 gallons a day × 20.5 gpg = 4,619 grains a day. A 48,000-grain unit regenerates about every 10 days.

Size it for your household

EPA record for Pocatello's water system

Pocatello City of · PWSID ID6030043

1 health-based violation since 2016

Serves about 58,231 people from groundwater.

Health-based
1
Monitoring or reporting
437
Open now
0
20162017201820192020202120222023202420252026Nitrate'16'18'20'22'24'26Nitrate
Each dot is one health-based violation, placed at the start of its compliance period.
Contaminant or ruleViolationsPeriodStatus
Nitrateoften from fertilizer or septic systems12021Resolved

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 Pocatello water hard?

Yes. It measures about 351 mg/L (20.5 grains per gallon), which the USGS classes as very hard.

What is the water hardness in Pocatello in grains per gallon?

About 20.5 gpg. One grain per gallon equals 17.1 mg/L, so 351 mg/L divided by 17.1 gives 20.5.

What size water softener do I need in Pocatello?

For 3 people using 75 gallons each per day, 20.5 gpg works out to about 4,619 grains a day. A 48,000-grain softener covers that with a regeneration about every 10 days.

Has the Pocatello water system had EPA violations?

EPA records show 1 health-based violation for Pocatello City of since 2016, involving Nitrate. There were also 437 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, January 22, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.