Commercial Plumber in Foster City, CA

A Property Manager’s Guide to Plumbing in Foster City

Water and sewer come from EMID

The Estero Municipal Improvement District (EMID), run by Foster City’s Public Works Department, provides water and sewer service to Foster City and part of the City of San Mateo. EMID’s Wastewater Division maintains more than 43 miles of sewer lines, 8.5 miles of force mains and 49 pumping stations, which send the city’s wastewater to the San Mateo Wastewater Treatment Plant. Foster City/EMID owns 25% of that plant and the City of San Mateo owns 75% and operates it.

Save these numbers with your building’s emergency contacts: 650-286-8140 for the Wastewater Division during working hours (Monday to Thursday 7:30 a.m. to 4:30 p.m., Friday 7:30 a.m. to 3:30 p.m.), and 650-286-3345, Police Dispatch, after hours. The City asks that sewer overflows not be reported by email. Water leaks, broken hydrants and other water problems go to the Public Works Maintenance Division at 650-286-8140.

Sewer laterals: the owner’s pipe

EMID’s Sewer System Management Plan states that the District is not responsible for maintenance or repair of sewer service laterals. When a building backs up, City crews check the District’s manholes; if the blockage is in the lateral, they tell the customer to call a plumber or drain cleaning company. We found no Foster City ordinance requiring a lateral inspection at sale.

District sewer standards for new and rebuilt connections also matter on larger properties:

• Size: commercial connections and properties with five or more units get 6-inch laterals, and laterals 6 inches or larger connect at a manhole.
• One connection: each parcel has only one connection to the public main.
• Cleanouts: a cleanout where the building sewer leaves the building, kept watertight.
• Backwater valves: a lot whose finished pad is lower than the street where its sewer main runs needs a backwater valve on private property, in a valve box visible from the street. The owner keeps it working.

Because the lateral is the owner’s, a camera inspection on a schedule finds roots, sags and cracks before they back up into a unit.

Restaurants: the San Mateo/EMID grease permit

Grease is regulated through a program shared with the City of San Mateo, administered by San Mateo’s Department of Public Works, Regulatory Compliance Division (650-522-7300). The key points:

• Who needs a permit: any food store, eating place or food preparer that bakes or cooks on the premises. New businesses apply at least 30 days before they start discharging.
• Pretreatment: a grease trap or interceptor sized to the plumbing code; at minimum, every utensil cleaning sink and wok range drains through one.
• Cleaning: at the frequency set in the permit, and often enough that a device never holds more than 25% grease.
• Records and inspections: maintenance records on site, available on request; facilities are inspected annually, during business hours, and inspections may be unannounced.

County health inspectors don’t inspect grease devices; the City/District does. Interceptor pumping handles the device itself; scheduled hydro jetting keeps the kitchen lines leading to it clear.

Backflow and fire services

EMID’s water standard details call for a USC-listed double check detector assembly on fire sprinkler services, and a reduced-pressure principle assembly where a property has an auxiliary water supply or uses chemicals. Under the San Mateo County Environmental Health Cross Connection Control Program, assemblies are tested at installation or repair and at least once a year by a County-certified tester, who sends the report to the County within 10 days. Ask EMID how tests for your account are tracked. We install and repair backflow assemblies; see backflow preventers.

Permits for commercial plumbing work

The Building Division takes applications through its eTRAKiT portal or at the City Hall counter. Its commercial permit guide requires a permit to install, alter, repair or replace any plumbing system, and replacing a defective concealed drain or water pipe counts as new work. Clearing stoppages and stopping leaks without replacing pipe needs no permit. Every permit starts with a pre-inspection. For emergency repairs, the permit application is due the next working business day. Contractors need a Foster City business license, and work in the street or sidewalk needs a Public Works encroachment permit. In or within 100 yards of a residential district, construction equipment may run 7:30 a.m. to 8 p.m. on weekdays and 9 a.m. to 8 p.m. on weekends and holidays, which matters for condo and HOA jobs.

Water heaters: soft water and electrification help

EMID buys all of its water from the San Francisco Regional Water System, which the City lists as Hetch Hetchy water. The 2025 water quality report lists hardness averaging 62 ppm (range 8.1–112 ppm), so scale builds slowly, though tanks still need regular flushing. For a switch from gas, WestLight Energy (formerly Peninsula Clean Energy) offers businesses free Technical Design Assistance with no obligation; its business offers list no heat pump water heater rebate, so check eligibility before planning on one. See commercial water heaters.

Sources

City of Foster City / EMID: Wastewater · Public Works FAQs · Water · Water Quality · Water Quality Report · 2025 water quality report · Wastewater Management Plan · Sewer System Management Plan · City Standard Details · Water Standard Details · Building Division FAQs · Work Requiring a Permit, Commercial · eTRAKiT. City of San Mateo / EMID: Waste discharge permit instructions and FAQ · Waste discharge permit application. San Mateo County Health: Cross Connection Control Program. WestLight Energy: Home · Business rebates and offers · Electric buildings. Checked October 2026.