Whole-House Repiping in Sunnyvale, CA

A Homeowner’s Guide to Whole-House Repiping in Sunnyvale

How old Sunnyvale’s homes are

Sunnyvale’s 2023–2031 Housing Element (adopted December 2023) counts homes by year built, from 2015–2019 Census estimates:

Year built	Homes
1939 or earlier	1,046
1940 to 1959	13,103
1960 to 1979	23,867
1980 to 1999	13,673
2000 to 2009	3,538

The City says homes over 30 years old are likely to show rehabilitation needs, naming new plumbing among them, while adding that many have been remodeled or rebuilt. Galvanized supply pipe from the postwar decades corrodes inside, cuts pressure and leaks at threaded joints; pinhole leaks in aging copper are another reason owners repipe. Our repiping cost calculator gives a first estimate. See whole-house repiping.

Eichlers and slab homes

Joseph Eichler’s first homes went up in Sunnyvale in 1949. The City’s Eichler Design Guidelines (2009) count more than 1,000 built here through 1972 and list slab-on-grade construction, radiant floor heating, flat roofs and open-beam ceilings among their features. They also note that radiant floors often deteriorated where copper piping wasn’t available.

For a repipe, that means little hidden space for new lines. We map each run with you first and use the City’s rules for pipe within and underneath the building. Leaks under the slab are a separate repair; see slab leak repair and leak detection.

What the City requires (January 2026 brochure)

The Building Division’s Residential Water/Sewer Pipes brochure applies to permits submitted on or after January 1, 2026:

• Permit first: a plumbing permit is required to replace distribution pipes, and it must be obtained before the old system is removed.
• Materials: copper (Type K, L or M), malleable iron, galvanized steel, CPVC, PEX or other approved material meeting NSF 61. Plastic distribution lines need a label at the main electrical panel.
• Like materials: the system must be of like materials unless the Chief Building Official approves otherwise, with brass adapters, dielectric unions and listed fittings at transitions.
• Insulation: the first 5 feet of hot and cold pipe at the water heater, hot lines of 3/4 inch or larger, hot lines to the kitchen, buried hot lines and any recirculation loop.
• Backflow: non-removable backflow devices on every hose bib.
• Walls: opened shear walls, braced panels or firewalls are inspected before they’re covered.

Bonding, grounding and the two inspections

All re-pipes need a bonding jumper between the hot, cold and gas lines at the water heater, sized to the main panel. The brochure’s grounding rules call for a conductor from the panel to a ground rod and the cold water pipe, connected within the first 5 feet of pipe entering the building. Then come two inspections: rough plumbing with the new pipe exposed, and final when the work is done.

Service lines and water quality

The City owns the line from the main to the meter; the owner has the line from the meter to the building. Its service line inventory field-checked 1,150 lines and found no lead or galvanized service lines needing replacement on either side. The pipe inside your walls is a different matter. On repipe day the water goes off at the house shutoff; if yours can’t be found or won’t close, the City’s 24-hour water line, 408-730-7400, will help.

The 2025 water quality report shows SFPUC water averaging 60 ppm hardness in the north, Valley Water 97 ppm in the south, and City wells 290 ppm when they’re used for summer peaks. A few pockets of the city get water from Cal Water instead. See water line replacement. Compare other cities in our South Bay water hardness table.

Sources

City of Sunnyvale: Residential water/sewer pipes (rev. 1/2026) · 2023–2031 Housing Element (p. 3-40, Figure 3-30) · Eichler Design Guidelines (2009) · Lead-free water systems · 2025 water quality report · Water · Permit Center. Checked October 2026.