Hard water in Star, ID
County estimate from 437 water samples in Ada County · July 2026
- ID typical
- 118 mg/L
- Softener for 3 people
- 24k grain
- Data
- County estimate
Water samples from around Star put hardness at about 124 mg/L (7.2 gpg), which would be hard on the USGS scale. Treat this as a rough guide: it is the median of 437 samples taken across Ada County, mostly wells and streams, not a test of Star's treated tap water.
At 124 mg/L, Star 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 86 mg/L in Meridian to 400 in Twin Falls.
What 124 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 124 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.
3 people × 75 gallons a day × 7.2 gpg = 1,631 grains a day. A 24,000-grain unit regenerates about every 14 days.
EPA record for Star's water system
We could not match Star to a community water system in EPA's records. Your water bill or the yearly Consumer Confidence Report names the system and its ID.
Questions
Is Star water hard?
Yes. It measures about 124 mg/L (7.2 grains per gallon), which the USGS classes as hard.
What is the water hardness in Star in grains per gallon?
About 7.2 gpg. One grain per gallon equals 17.1 mg/L, so 124 mg/L divided by 17.1 gives 7.2.
What size water softener do I need in Star?
For 3 people using 75 gallons each per day, 7.2 gpg works out to about 1,631 grains a day. A 24,000-grain softener covers that with a regeneration about every 14 days.
Nearby cities
- Eagle90 mg/LModerately hard
- Meridian86 mg/LModerately hard
- Nampa170 mg/LHard
- Caldwell170 mg/LHard
- Garden City90 mg/LModerately hard
- Kuna90 mg/LModerately hard
- Boise City90 mg/LModerately hard
- Twin Falls400 mg/LVery hard
- Lewiston122 mg/LHard
- Chubbuck340 mg/LVery hard
Hardness data: TapWaterData US Water Hardness (county estimate, July 4, 2026), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.