How hard is the water in Bainbridge Island, WA?

Tap water hardness
70mg/L
4.1gpg
Moderately hard

Reported by Bainbridge Island City of · September 2025

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

Bainbridge Island water measures 70 mg/L (4.1 gpg) of hardness, moderately hard by USGS standards. The number comes from Bainbridge Island City of, dated September 2025.

Bainbridge Island on the hardness scale, with nearby cities
060120180240300360+WA typical 36Lake Forest Park: 30 mg/LLake Forest Park 30Seattle: 31 mg/LSeattle 31Shoreline: 31 mg/LShoreline 31White Center: 31 mg/LWhite Center 31Burien: 33 mg/LBurien 33Port Orchard: 39 mg/LPort Orchard 39Bremerton: 39 mg/LBremerton 39Tracyton: 49 mg/LTracyton 49Poulsbo: 67 mg/LPoulsbo 67Silverdale: 80 mg/LSilverdale 80Bainbridge Island 70mg/L as calcium carbonate060120180240300360+WA 36Seattle: 31 mg/LSeattle 31Shoreline: 31 mg/LShoreline 31Port Orchard: 39 mg/LPort Orcha. 39Tracyton: 49 mg/LTracyton 49Poulsbo: 67 mg/LPoulsbo 67Silverdale: 80 mg/LSilverdale 8070 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

Bainbridge Island sits 34 mg/L above the typical Washington figure of 36. Of the 10 nearest cities we track, 9 have softer water and 1 has harder. The range nearby runs from 30 mg/L in Lake Forest Park to 80 in Silverdale.

What 70 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 Bainbridge Island

3 people × 75 gallons a day × 4.1 gpg = 922 grains a day. A 24,000-grain unit regenerates about every 26 days.

Size it for your household

EPA record for Bainbridge Island's water system

Bainbridge Island City of · PWSID WA5397650

No health-based violations since 2016

Serves about 13,491 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 Bainbridge Island water hard?

Somewhat. It measures about 70 mg/L (4.1 grains per gallon), which the USGS classes as moderately hard.

What is the water hardness in Bainbridge Island in grains per gallon?

About 4.1 gpg. One grain per gallon equals 17.1 mg/L, so 70 mg/L divided by 17.1 gives 4.1.

What size water softener do I need in Bainbridge Island?

For 3 people using 75 gallons each per day, 4.1 gpg works out to about 922 grains a day. A 24,000-grain softener covers that with a regeneration about every 26 days.

Has the Bainbridge Island water system had EPA violations?

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

Nearby cities

All 145 cities in Washington

Hardness data: TapWaterData US Water Hardness (utility report, September 24, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.