Water hardness
San Jose, CA water hardness
San Jose's tap water measures 155 to 545 ppm, which is in the hard to very hard range. The number comes from San Jose Water Company's 2024 published data, measured at the tap.
350 ppm
Hard to Very hard
San Jose shower water
Hardness bands per the U.S. Geological Survey. Range: 155 to 545 ppm across service areas.
Source: San Jose Water Company, 2024.
San Jose Water Company serves different areas from different sources, so hardness depends on where in the service area you are. The range above spans the zones the utility publishes.
Elsewhere in California, San Diego tests at 276 ppm and Fresno at 129 ppm.
What San Jose Water Means for Hair and Skin
Above 180 ppm, minerals leave visible scale on fixtures, soap struggles to lather, and hair and skin carry a film that rinsing doesn't remove. This is the range where people notice hard water without being told.
This page is supported by AG Softener. Here is why it is relevant to your water.
AG Softener is a portable shower water softener built for renters.
Real ion-exchange softening (the whole-house technology, sized for a shower) installs in about ten minutes without a plumber, and comes down just as fast when you move.
Check Your Own Zip Code
Check the number for your exact address with the free zip lookup, or read the utility's own report linked above.