Hard water in Glendora, CA
Reported by Azusa Light and Water · September 2025
- CA typical
- 121 mg/L
- EPA health violations since 2016
- 0
- Softener for 3 people
- 24k grain
- Data
- Utility report
Glendora water measures 122 mg/L (7.2 gpg) of hardness, hard by USGS standards. The number comes from Azusa Light and Water, dated September 2025. Reports for this system disagree, with values from 72 to 122 mg/L.
Glendora sits close to the typical California figure of 121 mg/L. Of the 10 nearest cities we track, 4 have softer water and 6 have harder. The range nearby runs from 75 mg/L in Duarte to 275 in Charter Oak.
What 122 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 122 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 × 7.2 gpg = 1,609 grains a day. A 24,000-grain unit regenerates about every 14 days.
EPA record for Glendora's water system
No health-based violations since 2016
Serves about 44,411 people from surface water.
- Health-based
- 0
- Monitoring or reporting
- 1
- Open now
- 0
EPA lists Glendora-City, Water Dept. as the system serving Glendora. The hardness figure above comes from a different system's report, which TapWaterData uses for Glendora.
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 Glendora water hard?
Yes. It measures about 122 mg/L (7.2 grains per gallon), which the USGS classes as hard.
What is the water hardness in Glendora in grains per gallon?
About 7.2 gpg. One grain per gallon equals 17.1 mg/L, so 122 mg/L divided by 17.1 gives 7.2.
What size water softener do I need in Glendora?
For 3 people using 75 gallons each per day, 7.2 gpg works out to about 1,609 grains a day. A 24,000-grain softener covers that with a regeneration about every 14 days.
Has the Glendora water system had EPA violations?
EPA records show no health-based violations for Glendora-City, Water Dept. since 2016. There were also 1 monitoring or reporting violation, which are about late or missing tests and notices.
Nearby cities
- Charter Oak275 mg/LVery hard
- Citrus112 mg/LModerately hard
- San Dimas275 mg/LVery hard
- Azusa116 mg/LModerately hard
- Covina167 mg/LHard
- La Verne231 mg/LVery hard
- Vincent112 mg/LModerately hard
- Duarte75 mg/LModerately hard
- West Covina170 mg/LHard
- Walnut210 mg/LVery hard
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.