Tukwila, WA water hardness

Tap water hardness
37mg/L
2.1gpg
SoftReports range 37–53

Reported by Seattle Public Utilities · October 2025

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

Tukwila water measures 37 mg/L (2.1 gpg) of hardness, soft by USGS standards. The number comes from Seattle Public Utilities, dated October 2025. Reports for this system disagree, with values from 37 to 53 mg/L.

Tukwila on the hardness scale, with nearby cities
060120180240300360+WA typical 36Newcastle: 27 mg/LNewcastle 27White Center: 31 mg/LWhite Center 31Burien: 33 mg/LBurien 33Bryn Mawr-Skyway: 35 mg/LBryn Mawr-Skyway 35Mercer Island: 39 mg/LMercer Island 39Des Moines: 48 mg/LDes Moines 48Renton: 49 mg/LRenton 49Fairwood: 53 mg/LFairwood 53SeaTac: 64 mg/LSeaTac 64Normandy Park: 64 mg/LNormandy Park 64Tukwila 37mg/L as calcium carbonate060120180240300360+WA 36White Center: 31 mg/LWhite Cent. 31Burien: 33 mg/LBurien 33Bryn Mawr-Skyway: 35 mg/LBryn Mawr-. 35Renton: 49 mg/LRenton 49SeaTac: 64 mg/LSeaTac 64Normandy Park: 64 mg/LNormandy P. 6437 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

Tukwila sits close to the typical Washington figure of 36 mg/L. Of the 10 nearest cities we track, 4 have softer water and 6 have harder. The range nearby runs from 27 mg/L in Newcastle to 64 in SeaTac.

What 37 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 37 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 Tukwila's water system

Tukwila Water Department · PWSID WA5389500

No health-based violations since 2016

Serves about 36,298 people from surface water.

Health-based
0
Monitoring or reporting
0
Open now
0

EPA lists Tukwila Water Department as the system serving Tukwila. The hardness figure above comes from a different system's report, which TapWaterData uses for Tukwila.

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 Tukwila water hard?

No. It measures about 37 mg/L (2.1 grains per gallon), which the USGS classes as soft.

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

About 2.1 gpg. One grain per gallon equals 17.1 mg/L, so 37 mg/L divided by 17.1 gives 2.1.

Has the Tukwila water system had EPA violations?

EPA records show no health-based violations for Tukwila Water Department since 2016.

Nearby cities

All 145 cities in Washington

Hardness data: TapWaterData US Water Hardness (utility report, October 12, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.