Newcastle, WA water hardness

Tap water hardness
27mg/L
1.6gpg
Soft

Reported by Coal Creek Utility District · June 2025

WA typical
36 mg/L
EPA health violations since 2016
0
Data
Utility report

Tap water in Newcastle has about 27 mg/L of hardness, which is 1.6 grains per gallon. On the USGS scale that counts as soft. The number comes from Coal Creek Utility District, dated June 2025.

Newcastle on the hardness scale, with nearby cities
060120180240300360+WA typical 36East Renton Highlands: 30 mg/LEast Renton Highlands 30White Center: 31 mg/LWhite Center 31Bellevue: 34 mg/LBellevue 34Bryn Mawr-Skyway: 35 mg/LBryn Mawr-Skyway 35Tukwila: 37 mg/LTukwila 37Mercer Island: 39 mg/LMercer Island 39Issaquah: 41 mg/LIssaquah 41Renton: 49 mg/LRenton 49Fairwood: 53 mg/LFairwood 53Sammamish: 62 mg/LSammamish 62Newcastle 27mg/L as calcium carbonate060120180240300360+WA 36East Renton Highlands: 30 mg/LEast Rento. 30Bellevue: 34 mg/LBellevue 34Bryn Mawr-Skyway: 35 mg/LBryn Mawr-. 35Mercer Island: 39 mg/LMercer Isl. 39Issaquah: 41 mg/LIssaquah 41Renton: 49 mg/LRenton 4927 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

Newcastle sits close to the typical Washington figure of 36 mg/L. None of the 10 nearest cities we track has softer water. The range nearby runs from 30 mg/L in East Renton Highlands to 62 in Sammamish.

What 27 mg/L means at home

Soap and shampoo lather with very little product. Kettles and showerheads stay mostly free of white crust.

Some people notice that soap feels slow to rinse off in soft water. That slippery feel is normal and harmless.

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

Nothing, as far as hardness goes. At 27 mg/L a softener would have almost nothing to remove.

Carbon filter

If the water tastes of chlorine, a pitcher or faucet carbon filter takes care of that. It does not change hardness.

EPA record for Newcastle's water system

Coal Creek Utility District · PWSID WA5341750

No health-based violations since 2016

Serves about 15,989 people from surface water.

Health-based
0
Monitoring or reporting
1
Open now
0

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 Newcastle water hard?

No. It measures about 27 mg/L (1.6 grains per gallon), which the USGS classes as soft.

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

About 1.6 gpg. One grain per gallon equals 17.1 mg/L, so 27 mg/L divided by 17.1 gives 1.6.

Has the Newcastle water system had EPA violations?

EPA records show no health-based violations for Coal Creek Utility District since 2016. There were also 1 monitoring or reporting violation, which are about late or missing tests and notices.

Nearby cities

All 145 cities in Washington

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