How hard is the water in Clearlake, CA?

Tap water hardness

96mg/L

5.6gpg

Moderately hardReports range 96–118

Reported by Highlands Mutual Water Company · March 2023

CA typical: 121 mg/L
EPA health violations since 2016: 4
Softener for 3 people: 24k grain
Data: Utility report

Tap water in Clearlake has about 96 mg/L of hardness, which is 5.6 grains per gallon. On the USGS scale that counts as moderately hard. The number comes from Highlands Mutual Water Company, dated March 2023. Reports for this system disagree, with values from 96 to 118 mg/L.

Clearlake on the hardness scale, with nearby cities

Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

At 96 mg/L, Clearlake is 25 mg/L below the typical California figure of 121. Of the 10 nearest cities we track, 5 have softer water and 5 have harder. The range nearby runs from 33 mg/L in Colusa to 142 in Sebastopol.

What 96 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 Clearlake

3 people × 75 gallons a day × 5.6 gpg = 1,258 grains a day. A 24,000-grain unit regenerates about every 19 days.

Size it for your household

EPA record for Clearlake's water system

Highlands Mutual Water Company · PWSID CA1710003

4 health-based violations since 2016

Serves about 7,772 people from surface water.

Health-based: 4
Monitoring or reporting: 1
Open now: 0

Each dot is one health-based violation, placed at the start of its compliance period.

Contaminant or rule	Violations	Period	Status
Haloacetic acids (HAA5)a disinfection byproduct	4	2019–2021	Resolved

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 Clearlake water hard?

Somewhat. It measures about 96 mg/L (5.6 grains per gallon), which the USGS classes as moderately hard.

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

About 5.6 gpg. One grain per gallon equals 17.1 mg/L, so 96 mg/L divided by 17.1 gives 5.6.

What size water softener do I need in Clearlake?

For 3 people using 75 gallons each per day, 5.6 gpg works out to about 1,258 grains a day. A 24,000-grain softener covers that with a regeneration about every 19 days.

Has the Clearlake water system had EPA violations?

EPA records show 4 health-based violations for Highlands Mutual Water Company since 2016, involving Haloacetic acids (HAA5). There were also 1 monitoring or reporting violation, which are about late or missing tests and notices.

Nearby cities

All 515 cities in California

Hardness data: TapWaterData US Water Hardness (utility report, March 15, 2023), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.