How hard is the water in Monmouth Junction, NJ?

Tap water hardness
99mg/L
5.8gpg
Moderately hard

Reported by NJ American Water - Raritan · October 2025

NJ typical
80 mg/L
EPA health violations since 2016
0
Softener for 3 people
24k grain
Data
Utility report

Monmouth Junction water measures 99 mg/L (5.8 gpg) of hardness, moderately hard by USGS standards. The number comes from NJ American Water - Raritan, dated October 2025.

Monmouth Junction on the hardness scale, with nearby cities
060120180240300360+NJ typical 80Milltown: 66 mg/LMilltown 66Heathcote: 82 mg/LHeathcote 82Kendall Park: 82 mg/LKendall Park 82Dayton: 82 mg/LDayton 82Princeton Meadows: 100 mg/LPrinceton Meadows 100Princeton: 100 mg/LPrinceton 100Jamesburg: 100 mg/LJamesburg 100Belle Mead: 100 mg/LBelle Mead 100Blackwells Mills: 111 mg/LBlackwells Mills 111Franklin Park: 235 mg/LFranklin Park 235Monmouth Junction 99mg/L as calcium carbonate060120180240300360+NJ 80Heathcote: 82 mg/LHeathcote 82Kendall Park: 82 mg/LKendall Pa. 82Dayton: 82 mg/LDayton 82Princeton Meadows: 100 mg/LPrinceton. 100Princeton: 100 mg/LPrinceton 100Franklin Park: 235 mg/LFranklin P. 23599 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

Monmouth Junction sits 19 mg/L above the typical New Jersey figure of 80. Of the 10 nearest cities we track, 4 have softer water and 6 have harder. The range nearby runs from 66 mg/L in Milltown to 235 in Franklin Park.

What 99 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 Monmouth Junction

3 people × 75 gallons a day × 5.8 gpg = 1,300 grains a day. A 24,000-grain unit regenerates about every 18 days.

Size it for your household

EPA record for Monmouth Junction's water system

NJ American Water - Raritan · PWSID NJ2004002

No health-based violations since 2016

Serves about 615,430 people from surface water.

Health-based
0
Monitoring or reporting
2
Open now
0

TapWaterData ties Monmouth Junction to this system. EPA's service-area records do not name Monmouth Junction, 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 Monmouth Junction water hard?

Somewhat. It measures about 99 mg/L (5.8 grains per gallon), which the USGS classes as moderately hard.

What is the water hardness in Monmouth Junction in grains per gallon?

About 5.8 gpg. One grain per gallon equals 17.1 mg/L, so 99 mg/L divided by 17.1 gives 5.8.

What size water softener do I need in Monmouth Junction?

For 3 people using 75 gallons each per day, 5.8 gpg works out to about 1,300 grains a day. A 24,000-grain softener covers that with a regeneration about every 18 days.

Has the Monmouth Junction water system had EPA violations?

EPA records show no health-based violations for NJ American Water - Raritan since 2016. There were also 2 monitoring or reporting violations, which are about late or missing tests and notices.

Nearby cities

All 227 cities in New Jersey

Hardness data: TapWaterData US Water Hardness (utility report, October 6, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.