Hard water in Rowland Heights, CA
Reported by Walnut Valley Water District · September 2025
- CA typical
- 121 mg/L
- EPA health violations since 2016
- 0
- Softener for 3 people
- 24k grain
- Data
- Utility report
The water in Rowland Heights carries roughly 160 mg/L of dissolved calcium and magnesium, or 9.4 grains per gallon. That is hard water. The number comes from Walnut Valley Water District, dated September 2025. Reports for this system disagree, with values from 88 to 160 mg/L.
At 160 mg/L, Rowland Heights is 39 mg/L above the typical California figure of 121. Of the 10 nearest cities we track, 2 have softer water and 8 have harder. The range nearby runs from 117 mg/L in Hacienda Heights to 223 in Valinda.
What 160 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 160 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 × 9.4 gpg = 2,110 grains a day. A 24,000-grain unit regenerates about every 11 days.
EPA record for Rowland Heights's water system
No health-based violations since 2016
Serves about 100,941 people from surface water.
- Health-based
- 0
- Monitoring or reporting
- 0
- Open now
- 0
TapWaterData ties Rowland Heights to this system. EPA's service-area records do not name Rowland Heights, 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 Rowland Heights water hard?
Yes. It measures about 160 mg/L (9.4 grains per gallon), which the USGS classes as hard.
What is the water hardness in Rowland Heights in grains per gallon?
About 9.4 gpg. One grain per gallon equals 17.1 mg/L, so 160 mg/L divided by 17.1 gives 9.4.
What size water softener do I need in Rowland Heights?
For 3 people using 75 gallons each per day, 9.4 gpg works out to about 2,110 grains a day. A 24,000-grain softener covers that with a regeneration about every 11 days.
Has the Rowland Heights water system had EPA violations?
EPA records show no health-based violations for Walnut Valley Water District since 2016.
Nearby cities
- South San Jose Hills208 mg/LVery hard
- Brea191 mg/LVery hard
- La Habra168 mg/LHard
- Diamond Bar153 mg/LHard
- Walnut210 mg/LVery hard
- Hacienda Heights117 mg/LModerately hard
- Valinda223 mg/LVery hard
- West Covina170 mg/LHard
- Fullerton175 mg/LHard
- East Whittier174 mg/LHard
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.