24/7 Emergency Plumber in Cupertino, CA

A Homeowner’s Guide to Emergency Plumbing in Cupertino

First, stop the damage

Call us any time at (408) 978-3093; after hours the call goes to our emergency service and an on-call plumber is dispatched. While you wait:

• Burst pipe or failed supply line: close the fixture valve, or the house shutoff where the water line enters the house. Keep clear of water near outlets or the electrical panel.
• Sewage coming up a drain: stop running water anywhere in the house, including the washer and dishwasher, and call the Sanitary District (below).
• Leaking water heater: close the cold-water valve on top of the tank and turn the heater off, gas control to “off” or the breaker for an electric unit.
• Gas smell: don’t use switches or phones nearby. Leave, call 9-1-1, then PG&E at 1-800-743-5000.

Sewer backups: the Cupertino Sanitary District

The City of Cupertino doesn’t run the sewer. For most addresses the Cupertino Sanitary District does, and it asks to be called first when sewage backs up into a house or yard, a manhole overflows, or you smell raw sewage: (408) 253-7071 on weekdays from 8 a.m. to 5 p.m., (408) 299-2507 after hours and on weekends. It responds 24/7 and doesn’t monitor email for emergencies. A few addresses drain to the City of Sunnyvale’s system instead (408-730-7400); the City’s utility service-finder map shows which.

What the District can do depends on your property-line cleanout. With an accessible, serviceable one, it maintains the lateral under the street. The house lateral from there to the building is yours, and without a cleanout the District can’t reach its part at all. Homes with plumbing lower than the public sewer also need a working sewage backflow device; the District warns that a buried or damaged one can let sewage flow back into the house. See main drain and sewer cleaning and sewer line service in Cupertino.

Water emergencies: which company, which side of the meter

Cupertino is split between two private water companies; the City’s water service-finder map shows yours.

• California Water Service (Los Altos Suburban district) serves the northeastern part of the city: (650) 917-0152, which is also its after-hours number.
• San Jose Water serves the southeast and operates the City-owned system in western Cupertino: (408) 279-7900, listed as its 24-hour customer service line.

San Jose Water handles the service line from the main to the meter, plus the meter and box, and takes reports of leaks on its side around the clock. Everything from the meter to the house, including the house valve, is the owner’s. Don’t close the valve in the meter box yourself; San Jose Water asks you to call it, and says you’re responsible for any damage done there. If your house shutoff won’t close, that’s a repair we can make. See burst pipe repair and leak detection.

Slab homes and hidden leaks

The Fairgrove neighborhood’s 220 Eichlers, built in the early 1960s, sit on slab foundations with radiant-heat floors, according to the City’s Eichler Design Handbook. A warm spot in the floor, the sound of running water with every fixture off, or a meter that keeps spinning can mean a leak under the concrete. Shut off the water at the house valve and call; we locate the leak before opening anything. See slab leak repair.

After the emergency: permits and the follow-up repair

Clearing a stoppage or repairing a leak generally needs no City permit. Replacing a defective concealed pipe counts as new work and does; so does a replacement water heater, though a licensed contractor can pull an instant permit for a like-for-like standard gas tank at a non-HOA home. Sewer lateral repairs need both a City plumbing permit and a District sewer permit.

After hours, the job is quoted as a fixed price before we start, typically based on $200–$300 per hour, plus parts and drive time, with a minimum charge. When the damage is stopped, we can often finish the repair during regular hours, and we’ll say so on the phone.

Sources

Cupertino Sanitary District: Home · Backup/Overflow Emergencies · FAQ. City of Cupertino: Utilities · Water · Building Division FAQ · Instant permits · Eichler Design Handbook, Fairgrove. City of Sunnyvale: Sewer. San Jose Water: Contact us · Who’s responsible for what. California Water Service: Los Altos Suburban district · Is Cal Water responsible for plumbing leaks?. PG&E: Gas safety. Silicon Valley Clean Energy: Home Rebates. Checked November 2026.