How hard is the water in Vacaville, CA?

Tap water hardness
94mg/L
5.5gpg
Moderately hardReports range 94–125

Reported by City of Vacaville · October 2025

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

The water in Vacaville carries roughly 94 mg/L of dissolved calcium and magnesium, or 5.5 grains per gallon. That is moderately hard water. The number comes from City of Vacaville, dated October 2025. Reports for this system disagree, with values from 94 to 125 mg/L.

Vacaville on the hardness scale, with nearby cities
060120180240300360+CA typical 121Rio Vista: 49 mg/LRio Vista 49Napa: 54 mg/LNapa 54Benicia: 56 mg/LBenicia 56American Canyon: 65 mg/LAmerican Canyon 65Davis: 68 mg/LDavis 68Bay Point: 88 mg/LBay Point 88Suisun City: 107 mg/LSuisun City 107Fairfield: 109 mg/LFairfield 109Dixon: 152 mg/LDixon 152University of California-Davis: 212 mg/LUniversity of California-Davis 212Vacaville 94mg/L as calcium carbonate060120180240300360+CA 121Napa: 54 mg/LNapa 54Davis: 68 mg/LDavis 68Suisun City: 107 mg/LSuisun City 107Fairfield: 109 mg/LFairfield 109Dixon: 152 mg/LDixon 152University of California-Davis: 212 mg/LUniversity. 21294 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

Vacaville sits 27 mg/L below the typical California figure of 121. Of the 10 nearest cities we track, 6 have softer water and 4 have harder. The range nearby runs from 49 mg/L in Rio Vista to 212 in University of California-Davis.

What 94 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 Vacaville

3 people × 75 gallons a day × 5.5 gpg = 1,238 grains a day. A 24,000-grain unit regenerates about every 19 days.

Size it for your household

EPA record for Vacaville's water system

City of Vacaville · PWSID CA4810008

No health-based violations since 2016

Serves about 99,650 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 Vacaville water hard?

Somewhat. It measures about 94 mg/L (5.5 grains per gallon), which the USGS classes as moderately hard.

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

About 5.5 gpg. One grain per gallon equals 17.1 mg/L, so 94 mg/L divided by 17.1 gives 5.5.

What size water softener do I need in Vacaville?

For 3 people using 75 gallons each per day, 5.5 gpg works out to about 1,238 grains a day. A 24,000-grain softener covers that with a regeneration about every 19 days.

Has the Vacaville water system had EPA violations?

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

Nearby cities

All 515 cities in California

Hardness data: TapWaterData US Water Hardness (utility report, October 6, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.