Hard water in Downey, CA
Reported by Downey - City, Water Dept. · November 2024
- CA typical
- 121 mg/L
- EPA health violations since 2016
- 1
- Softener for 3 people
- 24k grain
- Data
- Utility report
The water in Downey carries roughly 247 mg/L of dissolved calcium and magnesium, or 14.4 grains per gallon. That is very hard water. The number comes from Downey - City, Water Dept., dated November 2024.
At 247 mg/L, Downey is 126 mg/L above the typical California figure of 121. None of the 10 nearest cities we track has harder water. The range nearby runs from 45 mg/L in Pico Rivera to 217 in South Gate.
What 247 mg/L means at home
Scale forms fast here. Kettles and coffee makers need regular descaling, and showerheads clog unless you clean them.
Tank water heaters collect mineral sediment that insulates the water from the burner, so flushing the tank matters more than usual.
Dishes and glass shower doors spot easily. Soap scum and a dull film on hair or laundry are common complaints.
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 247 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 × 14.4 gpg = 3,244 grains a day. A 24,000-grain unit regenerates about every 7 days.
EPA record for Downey's water system
1 health-based violation since 2016
Serves about 110,556 people from groundwater.
- Health-based
- 1
- Monitoring or reporting
- 0
- Open now
- 0
| Contaminant or rule | Violations | Period | Status |
|---|---|---|---|
| Total Coliform Rulebacteria | 1 | 2018 | Resolved |
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 Downey water hard?
Yes. It measures about 247 mg/L (14.4 grains per gallon), which the USGS classes as very hard.
What is the water hardness in Downey in grains per gallon?
About 14.4 gpg. One grain per gallon equals 17.1 mg/L, so 247 mg/L divided by 17.1 gives 14.4.
What size water softener do I need in Downey?
For 3 people using 75 gallons each per day, 14.4 gpg works out to about 3,244 grains a day. A 24,000-grain softener covers that with a regeneration about every 7 days.
Has the Downey water system had EPA violations?
EPA records show 1 health-based violation for Downey - City, Water Dept. since 2016, involving Total Coliform Rule.
Nearby cities
- Bell Gardens171 mg/LHard
- Paramount108 mg/LModerately hard
- Norwalk136 mg/LHard
- Bellflower119 mg/LModerately hard
- South Gate217 mg/LVery hard
- Santa Fe Springs61 mg/LModerately hard
- Commerce75 mg/LModerately hard
- Lynwood171 mg/LHard
- Pico Rivera45 mg/LSoft
- West Whittier-Los Nietos75 mg/LModerately hard
Hardness data: TapWaterData US Water Hardness (utility report, November 3, 2024), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.