How hard is the water in Rathdrum, ID?

Tap water hardness
110mg/L
6.4gpg
Moderately hard

Reported by Rathdrum City of · March 2022

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

Rathdrum water measures 110 mg/L (6.4 gpg) of hardness, moderately hard by USGS standards. The number comes from Rathdrum City of, dated March 2022.

Rathdrum on the hardness scale, with nearby cities
060120180240300360+ID typical 118Sandpoint: 49 mg/LSandpoint 49Eagle: 90 mg/LEagle 90Garden City: 90 mg/LGarden City 90Moscow: 111 mg/LMoscow 111Post Falls: 116 mg/LPost Falls 116Hayden: 118 mg/LHayden 118Coeur d'Alene: 118 mg/LCoeur d'Alene 118Lewiston: 122 mg/LLewiston 122Star: 124 mg/LStar 124Caldwell: 170 mg/LCaldwell 170Rathdrum 110mg/L as calcium carbonate060120180240300360+ID 118Sandpoint: 49 mg/LSandpoint 49Moscow: 111 mg/LMoscow 111Post Falls: 116 mg/LPost Falls 116Hayden: 118 mg/LHayden 118Coeur d'Alene: 118 mg/LCoeur d'Al. 118Lewiston: 122 mg/LLewiston 122110 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

Rathdrum sits close to the typical Idaho figure of 118 mg/L. Of the 10 nearest cities we track, 3 have softer water and 7 have harder. The range nearby runs from 49 mg/L in Sandpoint to 170 in Caldwell.

What 110 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 Rathdrum

3 people × 75 gallons a day × 6.4 gpg = 1,447 grains a day. A 24,000-grain unit regenerates about every 16 days.

Size it for your household

EPA record for Rathdrum's water system

Rathdrum City of · PWSID ID1280152

No health-based violations since 2016

Serves about 10,358 people from groundwater.

Health-based
0
Monitoring or reporting
4
Open now
1

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 Rathdrum water hard?

Somewhat. It measures about 110 mg/L (6.4 grains per gallon), which the USGS classes as moderately hard.

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

About 6.4 gpg. One grain per gallon equals 17.1 mg/L, so 110 mg/L divided by 17.1 gives 6.4.

What size water softener do I need in Rathdrum?

For 3 people using 75 gallons each per day, 6.4 gpg works out to about 1,447 grains a day. A 24,000-grain softener covers that with a regeneration about every 16 days.

Has the Rathdrum water system had EPA violations?

EPA records show no health-based violations for Rathdrum City of since 2016. There were also 4 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, March 2, 2022), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.