How hard is the water in Fillmore, CA?

Tap water hardness
77mg/L
4.5gpg
Moderately hardReports range 77–95

Reported by Elkins Ranch · October 2025

CA typical
121 mg/L
EPA health violations since 2016
2
Softener for 3 people
24k grain
Data
Utility report

Fillmore water measures 77 mg/L (4.5 gpg) of hardness, moderately hard by USGS standards. The number comes from Elkins Ranch, dated October 2025. Reports for this system disagree, with values from 77 to 95 mg/L.

Fillmore on the hardness scale, with nearby cities
060120180240300360+CA typical 121Westlake Village: 88 mg/LWestlake Village 88Thousand Oaks: 117 mg/LThousand Oaks 117Oak Park: 138 mg/LOak Park 138Simi Valley: 181 mg/LSimi Valley 181Moorpark: 190 mg/LMoorpark 190Camarillo: 218 mg/LCamarillo 218Castaic: 236 mg/LCastaic 236Stevenson Ranch: 236 mg/LStevenson Ranch 236El Rio: 278 mg/LEl Rio 278Santa Paula: 383 mg/LSanta Paula 383Fillmore 77mg/L as calcium carbonate060120180240300360+CA 121Thousand Oaks: 117 mg/LThousand O. 117Oak Park: 138 mg/LOak Park 138Simi Valley: 181 mg/LSimi Valley 181Moorpark: 190 mg/LMoorpark 190Camarillo: 218 mg/LCamarillo 218Santa Paula: 383 mg/LSanta Paula 38377 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

At 77 mg/L, Fillmore is 44 mg/L below the typical California figure of 121. None of the 10 nearest cities we track has softer water. The range nearby runs from 88 mg/L in Westlake Village to 383 in Santa Paula.

What 77 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 Fillmore

3 people × 75 gallons a day × 4.5 gpg = 1,008 grains a day. A 24,000-grain unit regenerates about every 23 days.

Size it for your household

EPA record for Fillmore's water system

Elkins Ranch · PWSID CA5601134

2 health-based violations since 2016

Serves about 150 people from surface water.

Health-based
2
Monitoring or reporting
2
Open now
2
20162017201820192020202120222023202420252026Surface Water Treatment RuleLead and Copper Rule'16'18'20'22'24'26Surface Water Treatment RuleLead and Copper Rule
Each dot is one health-based violation, placed at the start of its compliance period.
Contaminant or ruleViolationsPeriodStatus
Surface Water Treatment Rulefiltration and disinfection12025Resolved
Lead and Copper Rulecorrosion control and lead sampling120241 open

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 Fillmore water hard?

Somewhat. It measures about 77 mg/L (4.5 grains per gallon), which the USGS classes as moderately hard.

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

About 4.5 gpg. One grain per gallon equals 17.1 mg/L, so 77 mg/L divided by 17.1 gives 4.5.

What size water softener do I need in Fillmore?

For 3 people using 75 gallons each per day, 4.5 gpg works out to about 1,008 grains a day. A 24,000-grain softener covers that with a regeneration about every 23 days.

Has the Fillmore water system had EPA violations?

EPA records show 2 health-based violations for Elkins Ranch since 2016, involving Surface Water Treatment Rule, Lead and Copper Rule. There were also 2 monitoring or reporting violations, which are about late or missing tests and notices.

Nearby cities

All 515 cities in California

Hardness data: TapWaterData US Water Hardness (utility report, October 14, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.