Hard water in Chico, CA
Reported by Cal-Water Service CO.-Chico · July 2025
- CA typical
- 121 mg/L
- EPA health violations since 2016
- 0
- Softener for 3 people
- 24k grain
- Data
- Utility report
The water in Chico carries roughly 154 mg/L of dissolved calcium and magnesium, or 9.0 grains per gallon. That is hard water. The number comes from Cal-Water Service CO.-Chico, dated July 2025.
At 154 mg/L, Chico is 33 mg/L above the typical California figure of 121. Of the 10 nearest cities we track, 6 have softer water and 3 have harder. The range nearby runs from 13 mg/L in Grass Valley to 356 in Orland.
What 154 mg/L means at home
Expect white crust on faucets and showerheads, plus spots on dishes that come out of the dishwasher.
Kettles collect scale quickly. Water heaters build up sediment at the bottom of the tank, which makes them work harder over time.
Soap and detergent need a little more to lather, and soap scum shows up in the tub.
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
At 154 mg/L most of the trouble is scale, and only a few things deal with it.
Ion-exchange water softener
The standard whole-house fix. It swaps calcium and magnesium for sodium or potassium and needs salt plus a drain. Size it with the calculator below.
Salt-free conditioner
No salt and no drain line. It changes how minerals form scale instead of removing them, so water still tests hard.
Reverse osmosis or carbon filter
Under-sink reverse osmosis removes minerals from drinking water only. Plain carbon filters improve taste but do not soften.
3 people × 75 gallons a day × 9.0 gpg = 2,023 grains a day. A 24,000-grain unit regenerates about every 11 days.
EPA record for Chico's water system
No health-based violations since 2016
Serves about 110,473 people from groundwater.
- Health-based
- 0
- Monitoring or reporting
- 0
- Open now
- 0
TapWaterData ties Chico to this system. EPA's service-area records do not name Chico, 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 Chico water hard?
Yes. It measures about 154 mg/L (9.0 grains per gallon), which the USGS classes as hard.
What is the water hardness in Chico in grains per gallon?
About 9.0 gpg. One grain per gallon equals 17.1 mg/L, so 154 mg/L divided by 17.1 gives 9.0.
What size water softener do I need in Chico?
For 3 people using 75 gallons each per day, 9.0 gpg works out to about 2,023 grains a day. A 24,000-grain softener covers that with a regeneration about every 11 days.
Has the Chico water system had EPA violations?
EPA records show no health-based violations for Cal-Water Service CO.-Chico since 2016.
Nearby cities
- Durham154 mg/LHard
- Orland356 mg/LVery hard
- Oroville24 mg/LSoft
- Colusa33 mg/LSoft
- Marysville98 mg/LModerately hard
- Yuba City247 mg/LVery hard
- Cottonwood37 mg/LSoft
- Anderson98 mg/LModerately hard
- Grass Valley13 mg/LSoft
- Plumas Lake197 mg/LVery hard
Hardness data: TapWaterData US Water Hardness (utility report, July 2, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.