Water Hardness in Durham, CA
California · 1 zip codes · 8 matched water systems
City avg (weighted): 199 PPM
Dataset updated March 9, 20268 matched water systems in the city rollupIndividual systems and ZIPs can differ. Methodology
Is Durham, CA Water Hard or Soft?
The displayed hardness for Durham, CA is 36 PPM (2.1 GPG) from Thermalito Water & Sewer Dist, classified as soft. The citywide weighted average is 199 PPM.
Water hardness is not a drinking-water safety score. It measures calcium and magnesium minerals, and address-level results can shift by pressure zone, supply blend, building plumbing, or private well.
How this city reading is built
This city reading is a weighted rollup across 8 matched water systems and 1 ZIP code. Citywide readings are useful for comparison, but individual utility zones and ZIPs can differ.
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 Durham
These systems are matched to Durham, CA. Citywide readings are useful for comparison, but the system serving a specific address may differ from the city average.
| Water System | Source | Hardness | Pop. Served |
|---|---|---|---|
| Cal-Water Service Co.-Chico CA0410002 | groundwater | 250 PPM Very Hard | |
| South Feather W&P - Miners Ranch CA0410006 | surface water | 155 PPM Moderately Hard | |
| Thermalito Water & Sewer Dist CA0410008 | surface water | 36 PPM SoftUSGS estimate: 155 PPM | |
| Cal-Water Service Co.-Oroville CA0410005 | surface water | 35 PPM SoftUSGS estimate: 192 PPM | |
| Del Oro Water Co.-Paradise Pines CA0410011 | surface water | 105 PPM Slightly Hard |
Zip Codes in Durham, CA
What This Means For You
Use this city 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 Durham, CA.
Frequently Asked Questions
How hard is the water in Durham, CA?
The citywide weighted average water hardness in Durham, CA is 199 PPM (11.7 GPG), classified as hard. This is based on 8 matched water systems. The gauge highlights Thermalito Water & Sewer Dist, a verified treated-water system, because individual systems can differ from the citywide average.
Do I need a water softener in Durham, CA?
With a citywide average hardness of 199 PPM, a water softener is recommended for homes in Durham. Confirm your tap reading before sizing equipment.
Is hard water in Durham, CA 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 Durham, CA?
Durham, California is served by 8 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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Compare free lookups, soap tests, test strips, liquid drop kits, and lab tests for measuring water hardness.
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