Mountlake Terrace, WA water hardness

Tap water hardness
14mg/L
0.8gpg
Soft

Reported by Mountlake Terrace City of · March 2025

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

The water in Mountlake Terrace carries roughly 14 mg/L of dissolved calcium and magnesium, or 0.8 grains per gallon. That is soft water. The number comes from Mountlake Terrace City of, dated March 2025.

Mountlake Terrace on the hardness scale, with nearby cities
060120180240300360+WA typical 36Brier: 13 mg/LBrier 13Alderwood Manor: 13 mg/LAlderwood Manor 13Bothell West: 13 mg/LBothell West 13North Lynnwood: 13 mg/LNorth Lynnwood 13Martha Lake: 13 mg/LMartha Lake 13Lynnwood: 15 mg/LLynnwood 15Kenmore: 25 mg/LKenmore 25Lake Forest Park: 30 mg/LLake Forest Park 30Shoreline: 31 mg/LShoreline 31Edmonds: 35 mg/LEdmonds 35Mountlake Terrace 14mg/L as calcium carbonate060120180240300360+WA 36Brier: 13 mg/LBrier 13Alderwood Manor: 13 mg/LAlderwood. 13Bothell West: 13 mg/LBothell We. 13Lynnwood: 15 mg/LLynnwood 15Lake Forest Park: 30 mg/LLake Fores. 30Edmonds: 35 mg/LEdmonds 3514 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

Mountlake Terrace sits 22 mg/L below the typical Washington figure of 36. Of the 10 nearest cities we track, 5 have softer water and 5 have harder. The range nearby runs from 13 mg/L in Brier to 35 in Edmonds.

What 14 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 14 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 Mountlake Terrace's water system

Mountlake Terrace City of · PWSID WA5357250

No health-based violations since 2016

Serves about 26,402 people from surface water.

Health-based
0
Monitoring or reporting
6
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 Mountlake Terrace water hard?

No. It measures about 14 mg/L (0.8 grains per gallon), which the USGS classes as soft.

What is the water hardness in Mountlake Terrace in grains per gallon?

About 0.8 gpg. One grain per gallon equals 17.1 mg/L, so 14 mg/L divided by 17.1 gives 0.8.

Has the Mountlake Terrace water system had EPA violations?

EPA records show no health-based violations for Mountlake Terrace City of since 2016. There were also 6 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, March 10, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.