How hard is the water in Plum, PA?

Tap water hardness
66mg/L
3.9gpg
Moderately hard

Reported by Mawc Sweeney Plant · February 2025

PA typical
127 mg/L
EPA health violations since 2016
2
Softener for 3 people
24k grain
Data
Utility report

Tap water in Plum has about 66 mg/L of hardness, which is 3.9 grains per gallon. On the USGS scale that counts as moderately hard. The number comes from Mawc Sweeney Plant, dated February 2025.

Plum on the hardness scale, with nearby cities
060120180240300360+PA typical 127Glenshaw: 88 mg/LGlenshaw 88Allison Park: 88 mg/LAllison Park 88Oakmont: 90 mg/LOakmont 90Wilkinsburg: 90 mg/LWilkinsburg 90Forest Hills: 90 mg/LForest Hills 90Swissvale: 90 mg/LSwissvale 90Monroeville: 96 mg/LMonroeville 96Fox Chapel: 102 mg/LFox Chapel 102Duquesne: 102 mg/LDuquesne 102Munhall: 102 mg/LMunhall 102Plum 66mg/L as calcium carbonate060120180240300360+PA 127Oakmont: 90 mg/LOakmont 90Wilkinsburg: 90 mg/LWilkinsburg 90Forest Hills: 90 mg/LForest Hil. 90Swissvale: 90 mg/LSwissvale 90Monroeville: 96 mg/LMonroeville 96Fox Chapel: 102 mg/LFox Chapel 10266 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

At 66 mg/L, Plum is 61 mg/L below the typical Pennsylvania figure of 127. None of the 10 nearest cities we track has softer water. The range nearby runs from 88 mg/L in Glenshaw to 102 in Fox Chapel.

What 66 mg/L means at home

You may see faint white spots on glasses and shower doors after the water dries.

Scale builds up slowly. A kettle or coffee maker needs descaling now and then, maybe every few months.

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

Optional. Plenty of households at this level live with it and descale the kettle now and then.

Water softener

Worth a look if spots on glass bother you, or if your tankless water heater manual asks for softer water.

Carbon filter

Improves taste and removes chlorine. It leaves calcium and magnesium in place.

Softener size for Plum

3 people × 75 gallons a day × 3.9 gpg = 866 grains a day. A 24,000-grain unit regenerates about every 27 days.

Size it for your household

EPA record for Plum's water system

Mawc Sweeney Plant · PWSID PA5650032

2 health-based violations since 2016

Serves about 143,000 people from surface water.

Health-based
2
Monitoring or reporting
21
Open now
0

TapWaterData ties Plum to this system. EPA's service-area records do not name Plum, so check the utility printed on your water bill.

20162017201820192020202120222023202420252026Total organic carbon removal'16'18'20'22'24'26Total organic carbon removal
Each dot is one health-based violation, placed at the start of its compliance period.
Contaminant or ruleViolationsPeriodStatus
Total organic carbon removaltreatment requirement22018–2019Resolved

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 Plum water hard?

Somewhat. It measures about 66 mg/L (3.9 grains per gallon), which the USGS classes as moderately hard.

What is the water hardness in Plum in grains per gallon?

About 3.9 gpg. One grain per gallon equals 17.1 mg/L, so 66 mg/L divided by 17.1 gives 3.9.

What size water softener do I need in Plum?

For 3 people using 75 gallons each per day, 3.9 gpg works out to about 866 grains a day. A 24,000-grain softener covers that with a regeneration about every 27 days.

Has the Plum water system had EPA violations?

EPA records show 2 health-based violations for Mawc Sweeney Plant since 2016, involving Total organic carbon removal. There were also 21 monitoring or reporting violations, which are about late or missing tests and notices.

Nearby cities

All 172 cities in Pennsylvania

Hardness data: TapWaterData US Water Hardness (utility report, February 17, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.