How hard is the water in Kennewick, WA?

Tap water hardness
96mg/L
5.6gpg
Moderately hardReports range 96–155

Reported by Kennewick City of · June 2025

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

Kennewick water measures 96 mg/L (5.6 gpg) of hardness, moderately hard by USGS standards. The number comes from Kennewick City of, dated June 2025. Reports for this system disagree, with values from 96 to 155 mg/L.

Kennewick on the hardness scale, with nearby cities
060120180240300360+WA typical 36West Richland: 33 mg/LWest Richland 33Othello: 33 mg/LOthello 33Walla Walla: 39 mg/LWalla Walla 39Toppenish: 63 mg/LToppenish 63Terrace Heights: 88 mg/LTerrace Heights 88Richland: 89 mg/LRichland 89Finley: 96 mg/LFinley 96Moses Lake: 168 mg/LMoses Lake 168Grandview: 208 mg/LGrandview 208Pasco: 268 mg/LPasco 268Kennewick 96mg/L as calcium carbonate060120180240300360+WA 36West Richland: 33 mg/LWest Richl. 33Walla Walla: 39 mg/LWalla Walla 39Richland: 89 mg/LRichland 89Finley: 96 mg/LFinley 96Grandview: 208 mg/LGrandview 208Pasco: 268 mg/LPasco 26896 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

At 96 mg/L, Kennewick is 60 mg/L above the typical Washington figure of 36. Of the 10 nearest cities we track, 6 have softer water and 3 have harder. The range nearby runs from 33 mg/L in West Richland to 268 in Pasco.

What 96 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 Kennewick

3 people × 75 gallons a day × 5.6 gpg = 1,264 grains a day. A 24,000-grain unit regenerates about every 18 days.

Size it for your household

EPA record for Kennewick's water system

Kennewick City of · PWSID WA5338100

No health-based violations since 2016

Serves about 118,164 people from surface water.

Health-based
0
Monitoring or reporting
5
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 Kennewick water hard?

Somewhat. It measures about 96 mg/L (5.6 grains per gallon), which the USGS classes as moderately hard.

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

About 5.6 gpg. One grain per gallon equals 17.1 mg/L, so 96 mg/L divided by 17.1 gives 5.6.

What size water softener do I need in Kennewick?

For 3 people using 75 gallons each per day, 5.6 gpg works out to about 1,264 grains a day. A 24,000-grain softener covers that with a regeneration about every 18 days.

Has the Kennewick water system had EPA violations?

EPA records show no health-based violations for Kennewick City of since 2016. There were also 5 monitoring or reporting violations, 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 16, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.