Hard water in King of Prussia, PA
Reported by Aqua PA Main System · October 2025
- PA typical
- 127 mg/L
- EPA health violations since 2016
- 2
- Softener for 3 people
- 24k grain
- Data
- Utility report
King of Prussia water measures 150 mg/L (8.8 gpg) of hardness, hard by USGS standards. The number comes from Aqua PA Main System, dated October 2025.
King of Prussia sits 23 mg/L above the typical Pennsylvania figure of 127. Of the 10 nearest cities we track, 4 have softer water and 6 have harder. The range nearby runs from 125 mg/L in Bridgeport to 153 in Wayne.
What 150 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 150 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 × 8.8 gpg = 1,978 grains a day. A 24,000-grain unit regenerates about every 12 days.
EPA record for King of Prussia's water system
2 health-based violations since 2016
Serves about 822,600 people from surface water.
- Health-based
- 2
- Monitoring or reporting
- 44
- Open now
- 0
TapWaterData ties King of Prussia to this system. EPA's service-area records do not name King of Prussia, so check the utility printed on your water bill.
| Contaminant or rule | Violations | Period | Status |
|---|---|---|---|
| Groundwater Ruletreatment of well water | 1 | 2024 | Resolved |
| Total Coliform Rulebacteria | 1 | 2017 | 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 King of Prussia water hard?
Yes. It measures about 150 mg/L (8.8 grains per gallon), which the USGS classes as hard.
What is the water hardness in King of Prussia in grains per gallon?
About 8.8 gpg. One grain per gallon equals 17.1 mg/L, so 150 mg/L divided by 17.1 gives 8.8.
What size water softener do I need in King of Prussia?
For 3 people using 75 gallons each per day, 8.8 gpg works out to about 1,978 grains a day. A 24,000-grain softener covers that with a regeneration about every 12 days.
Has the King of Prussia water system had EPA violations?
EPA records show 2 health-based violations for Aqua PA Main System since 2016, involving Groundwater Rule, Total Coliform Rule. There were also 44 monitoring or reporting violations, which are about late or missing tests and notices.
Nearby cities
- Bridgeport125 mg/LHard
- Norristown125 mg/LHard
- Audubon125 mg/LHard
- Trooper125 mg/LHard
- Wayne153 mg/LHard
- Conshohocken153 mg/LHard
- Villanova153 mg/LHard
- Chesterbrook153 mg/LHard
- Plymouth Meeting153 mg/LHard
- Bryn Mawr153 mg/LHard
All 172 cities in Pennsylvania
Hardness data: TapWaterData US Water Hardness (utility report, October 14, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.