Cottage Lake, WA water hardness

Tap water hardness
25mg/L
1.5gpg
Soft

Reported by Woodinville Water District · September 2025

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

Cottage Lake water measures 25 mg/L (1.5 gpg) of hardness, soft by USGS standards. The number comes from Woodinville Water District, dated September 2025.

Cottage Lake on the hardness scale, with nearby cities
060120180240300360+WA typical 36Bothell East: 13 mg/LBothell East 13Mill Creek East: 13 mg/LMill Creek East 13Maltby: 16 mg/LMaltby 16Bothell: 19 mg/LBothell 19Duvall: 21 mg/LDuvall 21Woodinville: 25 mg/LWoodinville 25Kenmore: 25 mg/LKenmore 25Kirkland: 34 mg/LKirkland 34Redmond: 39 mg/LRedmond 39Union Hill-Novelty Hill: 50 mg/LUnion Hill-Novelty Hill 50Cottage Lake 25mg/L as calcium carbonate060120180240300360+WA 36Maltby: 16 mg/LMaltby 16Bothell: 19 mg/LBothell 19Duvall: 21 mg/LDuvall 21Woodinville: 25 mg/LWoodinville 25Redmond: 39 mg/LRedmond 39Union Hill-Novelty Hill: 50 mg/LUnion Hill. 5025 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 25 mg/L, Cottage Lake is 11 mg/L below the typical Washington figure of 36. Of the 10 nearest cities we track, 5 have softer water and 3 have harder. The range nearby runs from 13 mg/L in Bothell East to 50 in Union Hill-Novelty Hill.

What 25 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 25 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 Cottage Lake's water system

Woodinville Water District · PWSID WA5341600

No health-based violations since 2016

Serves about 66,699 people from surface water.

Health-based
0
Monitoring or reporting
0
Open now
0

TapWaterData ties Cottage Lake to this system. EPA's service-area records do not name Cottage Lake, so check the utility printed on your water bill.

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 Cottage Lake water hard?

No. It measures about 25 mg/L (1.5 grains per gallon), which the USGS classes as soft.

What is the water hardness in Cottage Lake in grains per gallon?

About 1.5 gpg. One grain per gallon equals 17.1 mg/L, so 25 mg/L divided by 17.1 gives 1.5.

Has the Cottage Lake water system had EPA violations?

EPA records show no health-based violations for Woodinville Water District since 2016.

Nearby cities

All 145 cities in Washington

Hardness data: TapWaterData US Water Hardness (utility report, September 16, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.