How hard is the water in Mountain House, CA?

Tap water hardness
61mg/L
3.5gpg
Moderately hardReports range 61–74

Reported by Mountain House Community Services Dist. · March 2023

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

Mountain House water measures 61 mg/L (3.5 gpg) of hardness, moderately hard by USGS standards. The number comes from Mountain House Community Services Dist., dated March 2023. Reports for this system disagree, with values from 61 to 74 mg/L.

Mountain House on the hardness scale, with nearby cities
060120180240300360+CA typical 121Country Club: 10 mg/LCountry Club 10Camino Tassajara: 34 mg/LCamino Tassajara 34Tracy: 67 mg/LTracy 67Manteca: 75 mg/LManteca 75Antioch: 82 mg/LAntioch 82Brentwood: 86 mg/LBrentwood 86Oakley: 89 mg/LOakley 89Livermore: 94 mg/LLivermore 94Discovery Bay: 137 mg/LDiscovery Bay 137Pleasanton: 161 mg/LPleasanton 161Mountain House 61mg/L as calcium carbonate060120180240300360+CA 121Country Club: 10 mg/LCountry Cl. 10Tracy: 67 mg/LTracy 67Manteca: 75 mg/LManteca 75Brentwood: 86 mg/LBrentwood 86Livermore: 94 mg/LLivermore 94Discovery Bay: 137 mg/LDiscovery. 13761 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

Mountain House sits 60 mg/L below the typical California figure of 121. Of the 10 nearest cities we track, 2 have softer water and 8 have harder. The range nearby runs from 10 mg/L in Country Club to 161 in Pleasanton.

What 61 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 Mountain House

3 people × 75 gallons a day × 3.5 gpg = 797 grains a day. A 24,000-grain unit regenerates about every 30 days.

Size it for your household

EPA record for Mountain House's water system

City of Mountain House · PWSID CA3910027

No health-based violations since 2016

Serves about 26,400 people from surface water.

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 Mountain House water hard?

Somewhat. It measures about 61 mg/L (3.5 grains per gallon), which the USGS classes as moderately hard.

What is the water hardness in Mountain House in grains per gallon?

About 3.5 gpg. One grain per gallon equals 17.1 mg/L, so 61 mg/L divided by 17.1 gives 3.5.

What size water softener do I need in Mountain House?

For 3 people using 75 gallons each per day, 3.5 gpg works out to about 797 grains a day. A 24,000-grain softener covers that with a regeneration about every 30 days.

Has the Mountain House water system had EPA violations?

EPA records show no health-based violations for City of Mountain House since 2016.

Nearby cities

All 515 cities in California

Hardness data: TapWaterData US Water Hardness (utility report, March 29, 2023), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.