Water Heater Repair and Replacement in Cupertino, CA

A Homeowner’s Guide to Water Heater Repair and Replacement in Cupertino

Instant or standard permit

Cupertino’s handout states it plainly: every water heater installation or replacement needs a plumbing permit, followed by a water heater inspection and a final building inspection. How fast the permit comes depends on the heater:

• Instant permit: licensed contractors only, through Accela Citizen Access. It covers a standard gas tank of the same or lower BTU rating, not tankless and not at an HOA property.
• Standard building permit: everything else, including every heat pump and tankless water heater.

Questions go to the Permit Center at (408) 777-3228 or permitcenter@cupertino.gov. We pull the permit for you as part of the job. See water heater repair and replacement.

What the City’s handout requires

The Building Division’s Water Heater Installation and Replacement handout (revised June 11, 2026) sets the minimum 2025 California Plumbing Code checks:

• Seismic bracing: straps in the upper and lower thirds, the lower at least 4 inches above the controls; other methods need the City’s approval.
• Expansion tank: required on a closed system, whatever type of heater, installed on the building side of the check valve or backflow preventer and sized to the maker’s instructions.
• Relief valve drain: full size, by gravity, unthreaded, pointing down, ending 6 inches to 2 feet above the ground, never into the pan, and easy to see.
• Venting: a Type B or L vent at least 5 feet above the highest draft hood, through roof flashing to a listed cap, and 3 feet above a forced-air inlet within 10 feet.
• Gas: a sediment trap after the shutoff and bonded aboveground gas piping.
• Insulation: domestic hot water piping insulated to the pipe’s diameter.
• Location: 18-inch burner height in garages unless flammable-vapor ignition resistant, barriers against cars, a drain pan where a leak could cause damage, and attic access of at least 22 by 30 inches with a platform, outlet and light.

Two water companies, both partly on groundwater

The City’s water page lists three systems: California Water Service in the northeast, San Jose Water in the southeast, and the City-owned system in the west, which has two wells and is run by San Jose Water under a lease extended to 2036. Their 2025 reports:

Supplier	Groundwater hardness (avg., range)	Valley Water hardness (avg.)
Cal Water, Los Altos Suburban	305 ppm (137–440)	97 ppm
San Jose Water, incl. City system	288 ppm (175–451)	99 ppm

Groundwater-heavy water leaves sediment in tanks and scale on tankless heat exchangers, so flushing and descaling matter more here. See tankless water heaters.

Gas water heaters and the Air District

Cupertino’s electrification codes address new buildings, and the City suspended enforcement of its all-electric chapter on May 15, 2024. For a replacement, the regional rule is the one to watch. Under the Bay Area Air District’s Rule 9-6:

• gas water heaters of 75,000 BTU/hr or less manufactured after January 1, 2027 must be zero-NOx; larger units, tankless included, follow on January 1, 2031;
• on November 4, 2026 the Board votes on moving those dates to 2028 and 2033 and adding exemption certificates;
• working heaters can stay, and propane units aren’t covered.

See the zero-NOx rules and gas water heaters.

Heat pump water heaters and SVCE

Cupertino is in Silicon Valley Clean Energy’s service area. Its Home Rebates pay toward a heat pump water heater that replaces gas or electric resistance in a home of up to four units. Conditions from SVCE’s April 2026 specifications: 40 gallons or more, NEEA Tier 3 or higher, a thermostatic mixing valve, proof of permitting, and no tankless models. Apply before installing; approved reservations hold up to 120 days, and SVCE asks emergency replacements to contact it. Because a heat pump unit needs a standard permit here, plan the reservation and permit together. See SVCE heat pump rebates and heat pump water heaters.

Sources

City of Cupertino: Instant Permits (Residential Only) · Forms, Handouts and Fee Schedules · Water Heater Installation and Replacement (rev. 06.11.2026) · Water · All-Electric Building. San Jose Water: 2025 Annual Water Quality Report. California Water Service: 2025 Los Altos Suburban water quality report. Silicon Valley Clean Energy: Home Rebates · Appliance Specifications, April 2026 · Service area. Bay Area Air District: Rules 9-4 and 9-6 Building Appliances · Building Appliances Rule Implementation. Checked October 2026.