Hard water in Spokane, WA
Reported by Spokane City of · March 2025
- WA typical
- 36 mg/L
- EPA health violations since 2016
- 0
- Softener for 3 people
- 24k grain
- Data
- Utility report
The water in Spokane carries roughly 131 mg/L of dissolved calcium and magnesium, or 7.7 grains per gallon. That is hard water. The number comes from Spokane City of, dated March 2025.
Spokane sits 95 mg/L above the typical Washington figure of 36. Of the 10 nearest cities we track, 6 have softer water and 2 have harder. The range nearby runs from 33 mg/L in Othello to 230 in Ephrata.
What 131 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 131 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 × 7.7 gpg = 1,724 grains a day. A 24,000-grain unit regenerates about every 13 days.
EPA record for Spokane's water system
No health-based violations since 2016
Serves about 346,138 people from groundwater.
- Health-based
- 0
- Monitoring or reporting
- 0
- Open now
- 0
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 Spokane water hard?
Yes. It measures about 131 mg/L (7.7 grains per gallon), which the USGS classes as hard.
What is the water hardness in Spokane in grains per gallon?
About 7.7 gpg. One grain per gallon equals 17.1 mg/L, so 131 mg/L divided by 17.1 gives 7.7.
What size water softener do I need in Spokane?
For 3 people using 75 gallons each per day, 7.7 gpg works out to about 1,724 grains a day. A 24,000-grain softener covers that with a regeneration about every 13 days.
Has the Spokane water system had EPA violations?
EPA records show no health-based violations for Spokane City of since 2016.
Nearby cities
- Town and Country130 mg/LHard
- Country Homes124 mg/LHard
- Airway Heights131 mg/LHard
- Mead124 mg/LHard
- Spokane Valley131 mg/LHard
- Cheney55 mg/LSoft
- Pullman115 mg/LModerately hard
- Moses Lake168 mg/LHard
- Othello33 mg/LSoft
- Ephrata230 mg/LVery hard
Hardness data: TapWaterData US Water Hardness (utility report, March 12, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.