Hard water in Moses Lake, WA
County estimate from 290 water samples in Grant County · July 2026
- WA typical
- 36 mg/L
- EPA health violations since 2016
- 0
- Softener for 3 people
- 24k grain
- Data
- County estimate
Water samples from around Moses Lake put hardness at about 168 mg/L (9.8 gpg), which would be hard on the USGS scale. Treat this as a rough guide: it is the median of 290 samples taken across Grant County, mostly wells and streams, not a test of Moses Lake's treated tap water.
Moses Lake sits 132 mg/L above the typical Washington figure of 36. Of the 10 nearest cities we track, 8 have softer water and 2 have harder. The range nearby runs from 33 mg/L in Othello to 268 in Pasco.
What 168 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 168 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 × 9.8 gpg = 2,210 grains a day. A 24,000-grain unit regenerates about every 10 days.
EPA record for Moses Lake's water system
No health-based violations since 2016
Serves about 32,428 people from groundwater.
- Health-based
- 0
- Monitoring or reporting
- 66
- Open now
- 0
EPA lists this system as serving Moses Lake.
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 Moses Lake water hard?
Yes. It measures about 168 mg/L (9.8 grains per gallon), which the USGS classes as hard.
What is the water hardness in Moses Lake in grains per gallon?
About 9.8 gpg. One grain per gallon equals 17.1 mg/L, so 168 mg/L divided by 17.1 gives 9.8.
What size water softener do I need in Moses Lake?
For 3 people using 75 gallons each per day, 9.8 gpg works out to about 2,210 grains a day. A 24,000-grain softener covers that with a regeneration about every 10 days.
Has the Moses Lake water system had EPA violations?
EPA records show no health-based violations for Moses Lake City of since 2016. There were also 66 monitoring or reporting violations, which are about late or missing tests and notices.
Nearby cities
- Ephrata230 mg/LVery hard
- Othello33 mg/LSoft
- East Wenatchee80 mg/LModerately hard
- Wenatchee80 mg/LModerately hard
- West Richland33 mg/LSoft
- Richland89 mg/LModerately hard
- Pasco268 mg/LVery hard
- Ellensburg60 mg/LSoft
- Kennewick96 mg/LModerately hard
- Terrace Heights88 mg/LModerately 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.