How hard is the water in Blackfoot, ID?

Tap water hardness
119mg/L
7.0gpg
Moderately hard

Reported by Blackfoot City of · January 2025

ID typical
118 mg/L
EPA health violations since 2016
2
Softener for 3 people
24k grain
Data
Utility report

Tap water in Blackfoot has about 119 mg/L of hardness, which is 7.0 grains per gallon. On the USGS scale that counts as moderately hard. The number comes from Blackfoot City of, dated January 2025.

Blackfoot 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 90Idaho Falls: 173 mg/LIdaho Falls 173Chubbuck: 340 mg/LChubbuck 340Pocatello: 351 mg/LPocatello 351Twin Falls: 400 mg/LTwin Falls 400Blackfoot 119mg/L as calcium carbonate060120180240300360+ID 118Rexburg: 72 mg/LRexburg 72Boise City: 90 mg/LBoise City 90Idaho Falls: 173 mg/LIdaho Falls 173Chubbuck: 340 mg/LChubbuck 340Pocatello: 351 mg/LPocatello 351Twin Falls: 400 mg/LTwin Falls 400119 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 119 mg/L, Blackfoot is close to the typical Idaho figure of 118 mg/L. Of the 10 nearest cities we track, 6 have softer water and 4 have harder. The range nearby runs from 72 mg/L in Rexburg to 400 in Twin Falls.

What 119 mg/L means at home

You may see faint white spots on glasses and shower doors after the water dries.

Scale builds up slowly. A kettle or coffee maker needs descaling now and then, maybe every few months.

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

Optional. Plenty of households at this level live with it and descale the kettle now and then.

Water softener

Worth a look if spots on glass bother you, or if your tankless water heater manual asks for softer water.

Carbon filter

Improves taste and removes chlorine. It leaves calcium and magnesium in place.

Softener size for Blackfoot

3 people × 75 gallons a day × 7.0 gpg = 1,566 grains a day. A 24,000-grain unit regenerates about every 15 days.

Size it for your household

EPA record for Blackfoot's water system

Blackfoot City of · PWSID ID6060007

2 health-based violations since 2016

Serves about 13,224 people from groundwater.

Health-based
2
Monitoring or reporting
88
Open now
0
20162017201820192020202120222023202420252026Total Coliform Rule'16'18'20'22'24'26Total Coliform Rule
Each dot is one health-based violation, placed at the start of its compliance period.
Contaminant or ruleViolationsPeriodStatus
Total Coliform Rulebacteria22021–2022Resolved

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 Blackfoot water hard?

Somewhat. It measures about 119 mg/L (7.0 grains per gallon), which the USGS classes as moderately hard.

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

About 7.0 gpg. One grain per gallon equals 17.1 mg/L, so 119 mg/L divided by 17.1 gives 7.0.

What size water softener do I need in Blackfoot?

For 3 people using 75 gallons each per day, 7.0 gpg works out to about 1,566 grains a day. A 24,000-grain softener covers that with a regeneration about every 15 days.

Has the Blackfoot water system had EPA violations?

EPA records show 2 health-based violations for Blackfoot City of since 2016, involving Total Coliform Rule. There were also 88 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 3, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.