Commercial Plumber in Cupertino, CA

A Property Manager’s Guide to Plumbing in Cupertino

Water: two companies and a City-owned system

Cupertino doesn’t run its own water operations. California Water Service serves the northeastern part of the city from its Los Altos Suburban district (650-917-0152, also the after-hours line). San Jose Water serves the southeastern part and also operates the City-owned system in western Cupertino under a lease that was extended in 2024 to 2036 (408-279-7900). Use the City’s service-finder map to confirm which company serves a building, and keep that company’s number with your emergency contacts.

Sewer: the Cupertino Sanitary District

Sewer service comes from the Cupertino Sanitary District, not the City (some parts of Cupertino are served by Sunnyvale’s sewer system instead). For backups, overflowing manholes or raw sewage, call 408-253-7071 on weekdays from 8 a.m. to 5 p.m., or 408-299-2507 after hours and on weekends.

Lateral responsibility hinges on the cleanout. The District maintains and repairs the lateral in the public street, but only where there is an accessible, serviceable cleanout at the property line; without one, it can’t service its portion. The owner is responsible for the private lateral, the cleanout and the connection point. For older properties, that makes a property-line cleanout and periodic camera inspection worth planning. The District also lists a Sewer Lateral Loan Program, adopted in 2014, for home and business owners upgrading private laterals and cleanouts; ask the District whether it is currently funded. See commercial sewer repair.

Two District rules matter for lower floors. Properties with plumbing lower than the public sewer need a sewage backflow prevention device as a condition of connection, and it has to stay accessible and working. In new construction and major remodels, a private sewage pump is required where the lowest plumbed floor is less than one foot above the rim of the nearest upstream manhole.

Restaurants and grease interceptors

Grease control devices in Cupertino go through the District’s plan check and inspection. The District’s standard detail calls for precast grease interceptors in sizes of 1,500, 2,000, 3,000 or 5,000 gallons (larger sizes need District approval), with plumbing matched to the lateral size and a sample box downstream. If a garbage enclosure drains to the sanitary sewer, its area drain needs a sand/oil separator. The District doesn’t publish pumping frequencies online, so confirm maintenance requirements with the District. Scheduled hydro jetting keeps the kitchen lines leading to the interceptor open.

Permits: City and District

The City’s Building Division issues instant online permits only to licensed contractors, and only for listed residential work; the water heater permit covers like-for-like standard gas tanks, not tankless or heat pump units, and not HOA properties. Anything else, including commercial water heaters and repipes, needs a standard building permit with electronic plan submittal through the Permit Center (408-777-3228). Contractors and subcontractors need a City business license before the final inspection.

Sewer work needs a separate District permit. Fees must be paid before work begins, the request references the City building permit number, and inspections are requested 48 hours in advance. The District requires closed-circuit video of new laterals and property-line cleanouts, plus a video inspection before construction when an existing lateral will be reused. Contractors working on public sewers must register with the District.

Backflow testing

Both water companies require backflow protection where water use calls for it. San Jose Water states that every backflow preventer must be tested and recorded at least once a year by certified testers, generally requires a reduced-pressure assembly, and asks customers to check with its Backflow Department (408-279-7872) before buying a device. Cal Water’s cross-connection staff decide whether a site needs an assembly and confirm that existing assemblies are tested annually. We install and repair the assemblies these rules require; see backflow preventers.

Water heaters: hard groundwater and SVCE rebates

Both companies serve a mix of local groundwater and treated Valley Water (San Jose Water also has mountain surface water). San Jose Water’s 2025 report shows its groundwater averaging 288 ppm hardness and Valley Water surface water about 99 ppm; Cal Water’s 2025 Los Altos Suburban report shows groundwater averaging 305 ppm and Valley Water about 97 ppm. Hard water builds scale in tanks, tankless heat exchangers and fixtures, so flushing and descaling matter. When it’s time to replace, Silicon Valley Clean Energy offers business rebates for heat pump water heaters that replace gas or electric units, scaled by tank size; a reservation is required before installation, and the claim needs proof of permitting. See commercial water heaters.

Sources

City of Cupertino: Utilities · Water · Building Division FAQ · Instant permits. Cupertino Sanitary District: Home · FAQ · Backups and overflows · Residents & commercial · Sewer permits · Contractors · Grease interceptor detail · Sanitary sewer notes. San Jose Water: Backflow · 2025 water quality report. California Water Service: Los Altos Suburban district · 2025 water quality report. Silicon Valley Clean Energy: Business rebate equipment specifications. Checked October 2026.