Santa Clara County · San Jose–Sunnyvale–Santa Clara metro
Plumbing help in San Jose, CA
Very Hard WaterOlder Pipes
In San Jose, how hard your water is depends on where it comes from. Valley groundwater is very hard, local mountain water is harder than average, and imported water is softer. That mix drives many local calls about scale, water heaters and softeners.
- Median home built
- 1976
- Built before 1980
- 59%
- Owner-occupied
- 56%
- Water hardness
- Very hard
- ≈ 16.8 grains/gal
- Winter
- Hard freezes are rare
- Plumbing code
- Local
The plumbing calls that come up most in San Jose
- Water Softener Installation
Homes served mostly by valley groundwater can see water above 16 grains per gallon, where softening protects heaters and fixtures.
- Water Heater Replacement
With the median home built in the mid-1970s, many houses are on their second or third water heater, and hard water shortens each one's life.
- Repiping
Older galvanized and early copper supply lines in mid-century homes cause pressure loss and pinhole leaks.
San Jose's very hard water and your plumbing
San Jose Water reports hardness by source: groundwater averages about 16.8 grains per gallon (10.2 to 26.4), local mountain surface water about 9, and purchased imported water about 5.8 (4.5 to 8.5). [1]
Emergency plumbing in San Jose
Call (833) 878-1592Shut off your main water supply if it's safe to do so. The emergencies below are listed most likely first for San Jose homes, based on local conditions.
San Jose's 1970s housing and its pipes
The median home in San Jose was built in 1976, and 59% of homes predate 1980. Homes from that era were typically built with copper supply, early plastic (ABS or PVC) drains, some cast iron.
- Galvanized steel supply (1900–1960)
- Copper supply (1950–2000)
- Polybutylene (some homes) (1978–1996)
- PEX / CPVC (1995–today)
Plumbing services for San Jose homes
San Jose plumbing questions
Why does my San Jose water hardness change?
San Jose Water blends groundwater, local mountain water and imported water, which have very different hardness. The mix at your address can shift with the season and demand.
What hardness should I set my softener to in San Jose?
Test at your tap or check San Jose Water's report for your area. Groundwater-heavy areas can exceed 16 grains per gallon, while imported water is closer to 6.
Sources (2)
- U.S. Census Bureau, ACS 2024 1-year (B25035) · checked 2026-10-01
- San Jose Water, 2025 Annual Water Quality Report (main system) · checked 2026-10-01