Water Hardness in 95023
Hollister, California · San Benito County
Dataset updated March 9, 2026Matched to 19 water systemsTap readings can vary by utility zone, treatment, and plumbing. Methodology
How this ZIP reading is built
This ZIP reading is built from 19 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.
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 95023
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.
| Water System | Source | Hardness | Pop. Served |
|---|---|---|---|
| Hollister, City Of CA3510001 | surface water | 148 PPM Moderately HardUSGS estimate: 587 PPM | |
| Sunnyslope County Water Dist CA3510003 | surface water | 587 PPM Very Hard | |
| Rancho San Joaquin Mwc CA3500581 | groundwater | 587 PPM Very Hard | |
| Casa De Fruta Water System CA4300611 | groundwater | 587 PPM Very Hard | |
| Csa No. 31 Stonegate Ws CA3500006 | surface water | 587 PPM Very Hard |
Nearby Zip Codes
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.
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 Hollister, CA (95023).
Frequently Asked Questions
Is the water hard in Hollister, CA (95023)?
The average water hardness in 95023 is 374 PPM (21.9 GPG), which is classified as very hard.
Do I need a water softener in 95023?
With hardness of 374 PPM, a water softener is recommended for homes in 95023.
Is hard water in 95023 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 95023?
Zip code 95023 in Hollister, California is served by 19 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 readWater 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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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.
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