How hard is the water in Topanga, CA?

Tap water hardness
77mg/L
4.5gpg
Moderately hardReports range 77–112

Reported by Las Virgenes MWD · September 2025

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

Tap water in Topanga has about 77 mg/L of hardness, which is 4.5 grains per gallon. On the USGS scale that counts as moderately hard. The number comes from Las Virgenes MWD, dated September 2025. Reports for this system disagree, with values from 77 to 112 mg/L.

Topanga on the hardness scale, with nearby cities
060120180240300360+CA typical 121Santa Monica: 57 mg/LSanta Monica 57Calabasas: 77 mg/LCalabasas 77Agoura Hills: 88 mg/LAgoura Hills 88Westlake Village: 88 mg/LWestlake Village 88Beverly Hills: 121 mg/LBeverly Hills 121Marina del Rey: 121 mg/LMarina del Rey 121Los Angeles: 121 mg/LLos Angeles 121West Hollywood: 121 mg/LWest Hollywood 121Culver City: 122 mg/LCulver City 122Oak Park: 138 mg/LOak Park 138Topanga 77mg/L as calcium carbonate060120180240300360+CA 121Santa Monica: 57 mg/LSanta Moni. 57Calabasas: 77 mg/LCalabasas 77Agoura Hills: 88 mg/LAgoura Hil. 88Beverly Hills: 121 mg/LBeverly Hi. 121Marina del Rey: 121 mg/LMarina del. 121Oak Park: 138 mg/LOak Park 13877 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

Topanga sits 44 mg/L below the typical California figure of 121. Of the 10 nearest cities we track, 1 has softer water and 8 have harder. The range nearby runs from 57 mg/L in Santa Monica to 138 in Oak Park.

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 Topanga

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 Topanga's water system

Las Virgenes MWD · PWSID CA1910225

No health-based violations since 2016

Serves about 77,562 people from surface water.

Health-based
0
Monitoring or reporting
0
Open now
0

TapWaterData ties Topanga to this system. EPA's service-area records do not name Topanga, so check the utility printed on your water bill.

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 Topanga 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 Topanga 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 Topanga?

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 Topanga water system had EPA violations?

EPA records show no health-based violations for Las Virgenes MWD since 2016.

Nearby cities

All 515 cities in California

Hardness data: TapWaterData US Water Hardness (utility report, September 29, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.