San Jose
Is San Jose water hard or soft?
It can be either. San Jose is served by three utilities and several supplies, so the answer depends on your address. Curtner Avenue and Highway 101 are the main dividing lines on San Jose Water’s system.
| Area | Supply | Character | Disinfectant |
|---|---|---|---|
| San Jose Water, north of Curtner and west of 101 | Wells | Very hard | Chlorine |
| San Jose Water, most other areas | Los Gatos Creek | Hard | Chlorine |
| San Jose Water, south of Curtner and east of 101 | Treated Valley Water | Moderately hard | Chloramine |
| Municipal Water, Alviso and north of Trimble | Hetch Hetchy | Soft | Chloramine |
| Municipal Water, Evergreen | Valley Water and wells | Varies | Varies |
| Municipal Water, Edenvale and Coyote Valley | Wells | Very hard | Check your report |
| Great Oaks, South San Jose | Wells | Very hard | Check your report |
What this means at home
Hard water causes scale and spotting. Chloramine causes the taste and smell people notice, and it needs its own filter. Many homes have one or the other, and blends can change by season, so test at your own tap.
Sources: San Jose Water 2025 report, Valley Water retailer finder, City of San Jose water quality.
These are published ranges and general guidance, not quotes. In the Bay Area, Soft Patagonian offers free water tests.
Quick answers
Is San Jose water hard?
Much of it is. Areas on well water are very hard. Parts of the city on imported water, such as Alviso, are softer but treated with chloramine.
Does San Jose water have chloramine?
Parts of it do. San Jose Water areas south of Curtner Avenue and east of Highway 101 and San Jose Municipal Water areas such as Alviso receive chloraminated imported water.