WH

Water Hardness in 95358

Modesto, California · Stanislaus County

219 PPM
12.8 GPG
Hard
0Soft60120180300+
High Confidence - USGS Monitoring

Dataset updated March 9, 2026Matched to 16 water systemsTap readings can vary by utility zone, treatment, and plumbing. Methodology

Source context

How this ZIP reading is built

This ZIP reading is built from 16 matched water systems. When more than one system is matched, the displayed value is weighted toward larger known service populations when that data is available.

Source basis
13 USGS-backed sources
16 matched systems total for this ZIP; USGS monitoring is used where treated-water reports are unavailable.
Water source profile
Primarily surface water
Surface-water hardness can shift with reservoirs, runoff, season, and treatment. 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 Serving 95358

These are the systems matched to this ZIP code. The displayed ZIP value is weighted toward larger known service populations when population data is available.

16 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.
Modesto, City Of
CA5010010
Soft
27 PPMsurface water218,771 servedHigh Confidence - USGS Monitoring
Turlock, City Of
CA5010019
Very Hard
417 PPMsurface water72,682 servedHigh Confidence - USGS Monitoring
Ceres, City Of
CA5010028
Very Hard
417 PPMsurface water54,513 servedHigh Confidence - USGS Monitoring
Riverbank, City Of
CA5010018
Hard
223 PPMgroundwater24,834 servedHigh Confidence - USGS Monitoring
Patterson, City Of
CA5010017
Very Hard
779 PPMgroundwater23,304 servedEstimated - Nearby Data
Showing the first 5 systems. Expand to review all matched systems.

Nearby Zip Codes

953512189535021895368221953852219535421895387221953562189530722195355218953661119532822495337111

What This Means For You

Use this ZIP reading as a local planning estimate, not a final treatment specification. Hardness can vary by utility zone, seasonal blend, private well, and building plumbing. Confirm your tap reading with a utility report or home hardness test before sizing equipment.

MethodologyData sourcesHow to test your 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 Modesto, CA (95358).

Submit Your Data

Frequently Asked Questions

Is the water hard in Modesto, CA (95358)?

The average water hardness in 95358 is 219 PPM (12.8 GPG), which is classified as hard.

Do I need a water softener in 95358?

With hardness of 219 PPM, a water softener is recommended for homes in 95358.

Is hard water in 95358 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 95358?

Zip code 95358 in Modesto, California is served by 16 water systems.

Learn More About Your Water

How to Test Water Hardness at Home

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

8 min read

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.

10 min read

Well Water Hardness: Why It's Usually Hard & How to Treat It

Well water is almost always harder than city water. Learn why, how to test your well, and the best treatment options for hard well water.

8 min read