How hard is the water in Oakdale, CA?

Tap water hardness
94mg/L
5.5gpg
Moderately hard

Reported by Oakdale, City of · June 2025

CA typical
121 mg/L
EPA health violations since 2016
1
Softener for 3 people
24k grain
Data
Utility report

The water in Oakdale carries roughly 94 mg/L of dissolved calcium and magnesium, or 5.5 grains per gallon. That is moderately hard water. The number comes from Oakdale, City of, dated June 2025.

Oakdale on the hardness scale, with nearby cities
060120180240300360+CA typical 121Waterford: 16 mg/LWaterford 16Escalon: 28 mg/LEscalon 28Ripon: 28 mg/LRipon 28Modesto: 44 mg/LModesto 44Salida: 44 mg/LSalida 44West Modesto: 44 mg/LWest Modesto 44Ceres: 66 mg/LCeres 66Turlock: 98 mg/LTurlock 98Denair: 118 mg/LDenair 118Riverbank: 196 mg/LRiverbank 196Oakdale 94mg/L as calcium carbonate060120180240300360+CA 121Waterford: 16 mg/LWaterford 16Escalon: 28 mg/LEscalon 28Modesto: 44 mg/LModesto 44Salida: 44 mg/LSalida 44Ceres: 66 mg/LCeres 66Riverbank: 196 mg/LRiverbank 19694 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 94 mg/L, Oakdale is 27 mg/L below the typical California figure of 121. Of the 10 nearest cities we track, 7 have softer water and 3 have harder. The range nearby runs from 16 mg/L in Waterford to 196 in Riverbank.

What 94 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 Oakdale

3 people × 75 gallons a day × 5.5 gpg = 1,238 grains a day. A 24,000-grain unit regenerates about every 19 days.

Size it for your household

EPA record for Oakdale's water system

Oakdale, City of · PWSID CA5010014

1 health-based violation since 2016

Serves about 23,235 people from groundwater.

Health-based
1
Monitoring or reporting
1
Open now
0
20162017201820192020202120222023202420252026Lead and Copper Rule'16'18'20'22'24'26Lead and Copper Rule
Each dot is one health-based violation, placed at the start of its compliance period.
Contaminant or ruleViolationsPeriodStatus
Lead and Copper Rulecorrosion control and lead sampling12024Resolved

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 Oakdale water hard?

Somewhat. It measures about 94 mg/L (5.5 grains per gallon), which the USGS classes as moderately hard.

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

About 5.5 gpg. One grain per gallon equals 17.1 mg/L, so 94 mg/L divided by 17.1 gives 5.5.

What size water softener do I need in Oakdale?

For 3 people using 75 gallons each per day, 5.5 gpg works out to about 1,238 grains a day. A 24,000-grain softener covers that with a regeneration about every 19 days.

Has the Oakdale water system had EPA violations?

EPA records show 1 health-based violation for Oakdale, City of since 2016, involving Lead and Copper Rule. 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, June 2, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.