Every water company publishes an annual water quality report. Here is how to read San Jose’s, what it says about hardness and PFAS, and what it means if you are thinking about treatment at home.
Which report is yours
Start with your water bill: it names the company that supplies your home. San Jose Water’s 2025 annual water quality report covers two systems, its main system (CA4310011) and the City of Cupertino system (CA4310018). If another company supplies you, ask your water provider for its annual water quality report, which is sometimes called the Consumer Confidence Report or CCR. The sections below use San Jose Water’s 2025 report.
Where the water comes from
San Jose Water’s report describes three sources: mountain surface water, groundwater, and treated surface water from Valley Water. The report includes a map of which source feeds which area. That matters, because results such as hardness differ by source.
Hardness in the 2025 report
| Source | Average hardness (as calcium carbonate) | Range |
|---|---|---|
| Mountain surface water | 151 ppm, about 9 grains per gallon | Average given |
| Groundwater | 288 ppm, about 16.8 grains per gallon | 175 to 451 ppm |
| Valley Water treated surface water | 99 ppm, about 5.8 grains per gallon | 77 to 146 ppm |
On the USGS scale, 61 to 120 mg/L is moderately hard, 121 to 180 hard and more than 180 very hard. San Jose Water says hard water does not pose a health risk and there is no health-based drinking water standard for hardness. Our guide to hard water in San Jose goes into the figures.
PFAS in the report and in federal rules
San Jose Water’s 2025 report says it monitors 88 groundwater wells and 9 surface water sources for PFAS. For the results, read the PFAS section of the report itself.
The federal rules are changing, so date anything you read. EPA’s final rule set enforceable limits (maximum contaminant levels) of 4.0 parts per trillion for PFOA and for PFOS. On May 18, 2026 EPA proposed two rules: one keeps the PFOA and PFOS limits and lets water systems request two more years, to 2031, to comply; the other would rescind the limits for PFHxS, PFNA, HFPO-DA (GenX) and the hazard index mixture. When this page was written those were proposals, not final rules; EPA’s PFAS page has the current status.
Units you will meet in a water report
- ppm, parts per million: used for hardness and dissolved minerals. For water, a part per million is a milligram per liter.
- ppb, parts per billion: a thousand times smaller, used for some metals and other trace substances.
- ppt, parts per trillion: a million times smaller than ppm. The PFOA and PFOS limits are 4.0 ppt.
- Grains per gallon: the unit softeners are set in; about 17 mg/L of hardness per grain.
Taste, color and odor: EPA’s secondary guidelines
Some things in a report are about taste and appearance rather than health. EPA sets secondary standards for 15 such contaminants and does not enforce them: they are guidelines for aesthetic considerations such as taste, color and odor. Examples are total dissolved solids at 500 mg/L, chloride at 250 mg/L, iron at 0.3 mg/L and manganese at 0.05 mg/L, with a pH range of 6.5 to 8.5.
What the report means for treatment at home
A report tells you what is in the supply. It does not tell you what you want. If hardness bothers you, a softener deals with it: see water softener installation in San Jose. If something in the report concerns you, look for a filter or system certified to reduce that substance: water filtration in San Jose explains the NSF/ANSI standards, and reverse osmosis in San Jose covers treatment at the kitchen tap. This site makes no health claims about tap water or treated water.
The report covers the water your provider delivers. Your own pipes and fixtures sit between the main and your glass, so a test at your tap, from a state-certified laboratory, is the way to see what reaches you.
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Water Softener San Jose is an independent referral service, not an installer or plumber, and has no connection with San Jose Water or any other water company. When you send the form, your details are passed to an independent local water treatment pro, who can contact you and prepare a quote.
Questions people ask
Where can I find San Jose’s water quality report?
San Jose Water publishes its annual water quality report on its website (sjwater.com/ccr). If another company supplies your home, ask your water provider for its annual report.
Does San Jose water have PFAS?
San Jose Water’s 2025 report says it monitors 88 groundwater wells and 9 surface sources for PFAS. Read the report’s PFAS section for the results.
Is San Jose water hard?
It depends on the source: San Jose Water’s 2025 averages are about 5.8 grains per gallon for Valley Water treated surface water, 9 for mountain surface water and 16.8 for groundwater.
Is this site part of San Jose Water?
No. Water Softener San Jose is an independent referral service with no connection to any water company. For billing or service questions, contact your water company.