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Water Hardness in Onalaska, WA

Washington · 1 zip codes · 4 matched water systems

24 PPM
1.4 GPG
Soft
0Soft60120180300+
High Confidence — USGS Monitoring

Dataset updated March 9, 20264 matched water systems in the city rollupIndividual systems and ZIPs can differ. Methodology

Source context

How this city reading is built

This city reading is a weighted rollup across 4 matched water systems and 1 ZIP code. Citywide readings are useful for comparison, but individual utility zones and ZIPs can differ.

Source basis
2 USGS-backed sources
4 matched systems total for this city; USGS monitoring is used where treated-water reports are unavailable.
Water source profile
Primarily groundwater
Groundwater commonly picks up calcium and magnesium after contact with rock and soil. This profile is weighted by known population served across matched systems.
Data recency
March 9, 2026
Dataset rebuilt March 9, 2026; individual utility reporting years can vary.

Hardness is a mineral-content reading, not a drinking-water safety rating. Use it for scale, appliance, and softener decisions; check your utility report or test your tap before sizing treatment equipment. See how we calculate local readings.

Water Systems in Onalaska

These systems are matched to Onalaska, WA. Citywide readings are useful for comparison, but the system serving a specific address may differ from the city average.

4 water systems
PWSID is the public water system identifier. Data Source shows whether the hardness value comes from a treated-water report, USGS monitoring, or a local estimate; source year is shown when available.
Centralia Public Works - Water
WA5312200
Soft
19 PPMgroundwater28,164 servedHigh Confidence — USGS Monitoring
Chehalis Water Department
WA5312250
Soft
19 PPMsurface water11,426 servedHigh Confidence — USGS Monitoring
Boistfort Valley
WA5307610
Soft
55 PPMsurface water2,389 servedEstimated — County Avg
Lewis Co Water Dist #2
WA5347001
Slightly Hard
71 PPMgroundwater1,983 servedEstimated — Nearby Data

Zip Codes in Onalaska, WA

9857024

What This Means For You

Recommendations are based on the displayed hardness reading. Confirm your tap reading before sizing or buying treatment equipment.

Your Water Is Soft

Your water hardness is in the soft range. You likely don't need a water softener. Enjoy your naturally soft water!

Know your water hardness?

If you've tested your water or have your utility's CCR report, share your reading to help us improve accuracy for Onalaska, WA.

Submit Your Data

Frequently Asked Questions

How hard is the water in Onalaska, WA?

The citywide weighted average water hardness in Onalaska, WA is 24 PPM (1.4 GPG), classified as soft. This is based on 4 matched water systems.

Do I need a water softener in Onalaska, WA?

At 24 PPM, the citywide average is relatively soft. A water softener is generally not necessary.

Is hard water in Onalaska, WA safe to drink?

Water hardness itself is a mineral-content reading, not a drinking-water safety rating. Calcium and magnesium are naturally occurring minerals, but you should check your utility's Consumer Confidence Report for contaminant and compliance information.

How many water systems serve Onalaska, WA?

Onalaska, Washington is served by 4 matched water systems across 1 zip code.

Learn More About Your Water

Water Hardness Scale: PPM and GPG Chart

Use the USGS water hardness scale to compare PPM, GPG, and mg/L levels from soft to very hard water.

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How to Test Water Hardness at Home

Compare free lookups, soap tests, test strips, liquid drop kits, and lab tests for measuring water hardness.

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