Renton, WA water hardness

Tap water hardness
49mg/L
2.9gpg
Soft

Reported by Renton City of · October 2025

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

The water in Renton carries roughly 49 mg/L of dissolved calcium and magnesium, or 2.9 grains per gallon. That is soft water. The number comes from Renton City of, dated October 2025.

Renton on the hardness scale, with nearby cities
060120180240300360+WA typical 36Newcastle: 27 mg/LNewcastle 27East Renton Highlands: 30 mg/LEast Renton Highlands 30White Center: 31 mg/LWhite Center 31Burien: 33 mg/LBurien 33Bryn Mawr-Skyway: 35 mg/LBryn Mawr-Skyway 35Tukwila: 37 mg/LTukwila 37Mercer Island: 39 mg/LMercer Island 39Kent: 52 mg/LKent 52Fairwood: 53 mg/LFairwood 53SeaTac: 64 mg/LSeaTac 64Renton 49mg/L as calcium carbonate060120180240300360+WA 36Newcastle: 27 mg/LNewcastle 27East Renton Highlands: 30 mg/LEast Rento. 30Bryn Mawr-Skyway: 35 mg/LBryn Mawr-. 35Tukwila: 37 mg/LTukwila 37Fairwood: 53 mg/LFairwood 53SeaTac: 64 mg/LSeaTac 6449 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

Renton sits 13 mg/L above the typical Washington figure of 36. Of the 10 nearest cities we track, 7 have softer water and 3 have harder. The range nearby runs from 27 mg/L in Newcastle to 64 in SeaTac.

What 49 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 49 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 Renton's water system

Renton City of · PWSID WA5371850

No health-based violations since 2016

Serves about 108,091 people from groundwater.

Health-based
0
Monitoring or reporting
0
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 Renton water hard?

No. It measures about 49 mg/L (2.9 grains per gallon), which the USGS classes as soft.

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

About 2.9 gpg. One grain per gallon equals 17.1 mg/L, so 49 mg/L divided by 17.1 gives 2.9.

Has the Renton water system had EPA violations?

EPA records show no health-based violations for Renton City of since 2016.

Nearby cities

All 145 cities in Washington

Hardness data: TapWaterData US Water Hardness (utility report, October 7, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.