How hard is the water in Boise City, ID?

Tap water hardness
90mg/L
5.2gpg
Moderately hard

Reported by Veolia Water Idaho · October 2025

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

The water in Boise City carries roughly 90 mg/L of dissolved calcium and magnesium, or 5.2 grains per gallon. That is moderately hard water. The number comes from Veolia Water Idaho, dated October 2025.

Boise City on the hardness scale, with nearby cities
060120180240300360+ID typical 118Meridian: 86 mg/LMeridian 86Garden City: 90 mg/LGarden City 90Kuna: 90 mg/LKuna 90Eagle: 90 mg/LEagle 90Star: 124 mg/LStar 124Nampa: 170 mg/LNampa 170Caldwell: 170 mg/LCaldwell 170Chubbuck: 340 mg/LChubbuck 340Pocatello: 351 mg/LPocatello 351Twin Falls: 400 mg/LTwin Falls 400Boise City 90mg/L as calcium carbonate060120180240300360+ID 118Meridian: 86 mg/LMeridian 86Garden City: 90 mg/LGarden City 90Kuna: 90 mg/LKuna 90Eagle: 90 mg/LEagle 90Star: 124 mg/LStar 124Nampa: 170 mg/LNampa 17090 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 90 mg/L, Boise City is 28 mg/L below the typical Idaho figure of 118. Of the 10 nearest cities we track, 1 has softer water and 6 have harder. The range nearby runs from 86 mg/L in Meridian to 400 in Twin Falls.

What 90 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 Boise City

3 people × 75 gallons a day × 5.2 gpg = 1,177 grains a day. A 24,000-grain unit regenerates about every 20 days.

Size it for your household

EPA record for Boise City's water system

Veolia Water Idaho · PWSID ID4010016

No health-based violations since 2016

Serves about 264,978 people from surface water.

Health-based
0
Monitoring or reporting
2
Open now
0

TapWaterData ties Boise City to this system. EPA's service-area records do not name Boise City, so check the utility printed on your water bill.

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 Boise City water hard?

Somewhat. It measures about 90 mg/L (5.2 grains per gallon), which the USGS classes as moderately hard.

What is the water hardness in Boise City in grains per gallon?

About 5.2 gpg. One grain per gallon equals 17.1 mg/L, so 90 mg/L divided by 17.1 gives 5.2.

What size water softener do I need in Boise City?

For 3 people using 75 gallons each per day, 5.2 gpg works out to about 1,177 grains a day. A 24,000-grain softener covers that with a regeneration about every 20 days.

Has the Boise City water system had EPA violations?

EPA records show no health-based violations for Veolia Water Idaho since 2016. There were also 2 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, October 8, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.