How hard is the water in Daly City, CA?

Tap water hardness
73mg/L
4.3gpg
Moderately hard

Reported by City of Daly City · 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 Daly City has about 73 mg/L of hardness, which is 4.3 grains per gallon. On the USGS scale that counts as moderately hard. The number comes from City of Daly City, dated September 2025.

Daly City on the hardness scale, with nearby cities
060120180240300360+CA typical 121Burlingame: 31 mg/LBurlingame 31Alameda: 34 mg/LAlameda 34Hillsborough: 36 mg/LHillsborough 36San Bruno: 44 mg/LSan Bruno 44Millbrae: 44 mg/LMillbrae 44Sausalito: 56 mg/LSausalito 56Tiburon: 56 mg/LTiburon 56Tamalpais-Homestead Valley: 56 mg/LTamalpais-Homestead Valley 56South San Francisco: 64 mg/LSouth San Francisco 64Pacifica: 70 mg/LPacifica 70Daly City 73mg/L as calcium carbonate060120180240300360+CA 121Burlingame: 31 mg/LBurlingame 31San Bruno: 44 mg/LSan Bruno 44Millbrae: 44 mg/LMillbrae 44Sausalito: 56 mg/LSausalito 56South San Francisco: 64 mg/LSouth San. 64Pacifica: 70 mg/LPacifica 7073 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

Daly City sits 48 mg/L below the typical California figure of 121. None of the 10 nearest cities we track has harder water. The range nearby runs from 31 mg/L in Burlingame to 70 in Pacifica.

What 73 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 Daly City

3 people × 75 gallons a day × 4.3 gpg = 961 grains a day. A 24,000-grain unit regenerates about every 24 days.

Size it for your household

EPA record for Daly City's water system

City of Daly City · PWSID CA4110013

No health-based violations since 2016

Serves about 102,593 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 Daly City water hard?

Somewhat. It measures about 73 mg/L (4.3 grains per gallon), which the USGS classes as moderately hard.

What is the water hardness in Daly City in grains per gallon?

About 4.3 gpg. One grain per gallon equals 17.1 mg/L, so 73 mg/L divided by 17.1 gives 4.3.

What size water softener do I need in Daly City?

For 3 people using 75 gallons each per day, 4.3 gpg works out to about 961 grains a day. A 24,000-grain softener covers that with a regeneration about every 24 days.

Has the Daly City water system had EPA violations?

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

Nearby cities

All 515 cities in California

Hardness data: TapWaterData US Water Hardness (utility report, September 23, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.