Lake Oswego, OR water hardness

Tap water hardness
26mg/L
1.5gpg
Soft

Reported by Glenmorrie Cooperative Assn · July 2025

OR typical
24 mg/L
EPA health violations since 2016
0
Data
Utility report

The water in Lake Oswego carries roughly 26 mg/L of dissolved calcium and magnesium, or 1.5 grains per gallon. That is soft water. The number comes from Glenmorrie Cooperative Assn, dated July 2025.

Lake Oswego on the hardness scale, with nearby cities
060120180240300360+OR typical 24Tigard: 22 mg/LTigard 22Oak Grove: 23 mg/LOak Grove 23Jennings Lodge: 23 mg/LJennings Lodge 23West Linn: 23 mg/LWest Linn 23Garden Home-Whitford: 23 mg/LGarden Home-Whitford 23Gladstone: 23 mg/LGladstone 23Raleigh Hills: 35 mg/LRaleigh Hills 35Oatfield: 56 mg/LOatfield 56Tualatin: 77 mg/LTualatin 77Milwaukie: 120 mg/LMilwaukie 120Lake Oswego 26mg/L as calcium carbonate060120180240300360+OR 24Tigard: 22 mg/LTigard 22Oak Grove: 23 mg/LOak Grove 23Jennings Lodge: 23 mg/LJennings L. 23West Linn: 23 mg/LWest Linn 23Tualatin: 77 mg/LTualatin 77Milwaukie: 120 mg/LMilwaukie 12026 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

Lake Oswego sits close to the typical Oregon figure of 24 mg/L. Of the 10 nearest cities we track, 6 have softer water and 4 have harder. The range nearby runs from 22 mg/L in Tigard to 120 in Milwaukie.

What 26 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 26 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 Lake Oswego's water system

Glenmorrie Cooperative Assn · PWSID OR4100459

No health-based violations since 2016

Serves about 310 people from groundwater.

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 Lake Oswego water hard?

No. It measures about 26 mg/L (1.5 grains per gallon), which the USGS classes as soft.

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

About 1.5 gpg. One grain per gallon equals 17.1 mg/L, so 26 mg/L divided by 17.1 gives 1.5.

Has the Lake Oswego water system had EPA violations?

EPA records show no health-based violations for Glenmorrie Cooperative Assn since 2016. There were also 5 monitoring or reporting violations, which are about late or missing tests and notices.

Nearby cities

All 53 cities in Oregon

Hardness data: TapWaterData US Water Hardness (utility report, July 28, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.