San Anselmo, CA water hardness

Tap water hardness
56mg/L
3.3gpg
Soft

Reported by Marin Municipal Water District · October 2025

CA typical
121 mg/L
EPA health violations since 2016
0
Data
Utility report

Tap water in San Anselmo has about 56 mg/L of hardness, which is 3.3 grains per gallon. On the USGS scale that counts as soft. The number comes from Marin Municipal Water District, dated October 2025.

San Anselmo on the hardness scale, with nearby cities
060120180240300360+CA typical 121Fairfax: 56 mg/LFairfax 56Kentfield: 56 mg/LKentfield 56San Rafael: 56 mg/LSan Rafael 56Larkspur: 56 mg/LLarkspur 56Corte Madera: 56 mg/LCorte Madera 56Mill Valley: 56 mg/LMill Valley 56Strawberry: 56 mg/LStrawberry 56Tamalpais-Homestead Valley: 56 mg/LTamalpais-Homestead Valley 56Lucas Valley-Marinwood: 63 mg/LLucas Valley-Marinwood 63Novato: 63 mg/LNovato 63San Anselmo 56mg/L as calcium carbonate060120180240300360+CA 121Fairfax: 56 mg/LFairfax 56Kentfield: 56 mg/LKentfield 56San Rafael: 56 mg/LSan Rafael 56Larkspur: 56 mg/LLarkspur 56Corte Madera: 56 mg/LCorte Made. 56Lucas Valley-Marinwood: 63 mg/LLucas Vall. 6356 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 56 mg/L, San Anselmo is 65 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 56 mg/L in Fairfax to 63 in Lucas Valley-Marinwood.

What 56 mg/L means at home

Soap and shampoo lather with very little product. Kettles and showerheads stay mostly free of white crust.

Some people notice that soap feels slow to rinse off in soft water. That slippery feel is normal and harmless.

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

Nothing, as far as hardness goes. At 56 mg/L a softener would have almost nothing to remove.

Carbon filter

If the water tastes of chlorine, a pitcher or faucet carbon filter takes care of that. It does not change hardness.

EPA record for San Anselmo's water system

Marin Municipal Water District · PWSID CA2110002

No health-based violations since 2016

Serves about 188,116 people from surface water.

Health-based
0
Monitoring or reporting
0
Open now
0

TapWaterData ties San Anselmo to this system. EPA's service-area records do not name San Anselmo, 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 San Anselmo water hard?

No. It measures about 56 mg/L (3.3 grains per gallon), which the USGS classes as soft.

What is the water hardness in San Anselmo in grains per gallon?

About 3.3 gpg. One grain per gallon equals 17.1 mg/L, so 56 mg/L divided by 17.1 gives 3.3.

Has the San Anselmo water system had EPA violations?

EPA records show no health-based violations for Marin Municipal Water District 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.