How hard is the water in Iselin, NJ?

Tap water hardness
108mg/L
6.3gpg
Moderately hard

Reported by Middlesex Water Company · October 2025

NJ typical
80 mg/L
EPA health violations since 2016
1
Softener for 3 people
24k grain
Data
Utility report

Tap water in Iselin has about 108 mg/L of hardness, which is 6.3 grains per gallon. On the USGS scale that counts as moderately hard. The number comes from Middlesex Water Company, dated October 2025.

Iselin on the hardness scale, with nearby cities
060120180240300360+NJ typical 80Perth Amboy: 84 mg/LPerth Amboy 84Garwood: 100 mg/LGarwood 100South Plainfield: 102 mg/LSouth Plainfield 102Colonia: 108 mg/LColonia 108Woodbridge: 108 mg/LWoodbridge 108Fords: 108 mg/LFords 108Avenel: 108 mg/LAvenel 108Metuchen: 108 mg/LMetuchen 108Carteret: 108 mg/LCarteret 108Rahway: 196 mg/LRahway 196Iselin 108mg/L as calcium carbonate060120180240300360+NJ 80Colonia: 108 mg/LColonia 108Woodbridge: 108 mg/LWoodbridge 108Fords: 108 mg/LFords 108Avenel: 108 mg/LAvenel 108Metuchen: 108 mg/LMetuchen 108Rahway: 196 mg/LRahway 196108 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

Iselin sits 28 mg/L above the typical New Jersey figure of 80. Of the 10 nearest cities we track, 3 have softer water and 1 has harder. The range nearby runs from 84 mg/L in Perth Amboy to 196 in Rahway.

What 108 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 Iselin

3 people × 75 gallons a day × 6.3 gpg = 1,422 grains a day. A 24,000-grain unit regenerates about every 16 days.

Size it for your household

EPA record for Iselin's water system

Middlesex Water Company · PWSID NJ1225001

1 health-based violation since 2016

Serves about 233,376 people from surface water.

Health-based
1
Monitoring or reporting
9
Open now
0
20162017201820192020202120222023202420252026Lead and Copper Rule'16'18'20'22'24'26Lead and Copper Rule
Each dot is one health-based violation, placed at the start of its compliance period.
Contaminant or ruleViolationsPeriodStatus
Lead and Copper Rulecorrosion control and lead sampling12019Resolved

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 Iselin water hard?

Somewhat. It measures about 108 mg/L (6.3 grains per gallon), which the USGS classes as moderately hard.

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

About 6.3 gpg. One grain per gallon equals 17.1 mg/L, so 108 mg/L divided by 17.1 gives 6.3.

What size water softener do I need in Iselin?

For 3 people using 75 gallons each per day, 6.3 gpg works out to about 1,422 grains a day. A 24,000-grain softener covers that with a regeneration about every 16 days.

Has the Iselin water system had EPA violations?

EPA records show 1 health-based violation for Middlesex Water Company since 2016, involving Lead and Copper Rule. There were also 9 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 1, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.