Private Investor-Owned Utility
California Water Service - San Carlos System
Serving San Carlos and vicinity, San Mateo County
Population served
34,801 people; 9,359 residential, 1,034 commercial, and 74 industrial service connections reported for active PWS CA4110007
State system code
FIPS 06
Billing frequency
Monthly. The South San Francisco/San Carlos Bayshore district materials state that district services are metered, meters are read monthly, and customers are billed monthly based on metered water use. The issued statement controls the exact due date and service period.
Provider briefing
How this utility’s billing works
California Water Service - San Carlos System operates as a private investor-owned utility serving San Carlos and vicinity, San Mateo County. Customers should use the provider’s current account-specific bill and official customer-service instructions as the final authority for deadlines, balances, and service requests.
The published water-rate framework is described as Increasing-block conservation pricing for residential metered customers under CPUC Schedule BAR-1-R, Bay Area Region. Effective July 1, 2026, the 5/8 x 3/4-inch monthly readiness-to-serve charge is $34.47; usage is $4.2083 per CCF for 1–6 CCF, $16.8152 per CCF for 7–9 CCF, $21.0842 per CCF for 10–13 CCF, and $25.2184 per CCF above 13 CCF. One CCF is approximately 748 gallons. San Carlos residential bills also include a 1.111% San Carlos franchise-tax surcharge, and bills can include CPUC, Rate Support Fund, CAP, and other approved surcharges or surcredits.. Bills are generated monthly. the south san francisco/san carlos bayshore district materials state that district services are metered, meters are read monthly, and customers are billed monthly based on metered water use. the issued statement controls the exact due date and service period., and a typical residential cost reference is Using the July 2026 BAR-1-R 5/8 x 3/4-inch schedule, a 5,000-gallon month is about 6.68 CCF and produces approximately $71.15 in basic water charges, or about $71.94 after the 1.111% San Carlos franchise-tax surcharge, before other approved surcharges, surcredits, taxes, or separate sewer service. A 7,000-gallon month is about 9.36 CCF and produces approximately $117.76 in basic water charges, or about $119.07 after that surcharge. The exact bill depends on meter size, days in the billing period, usage, and line-item adjustments; this is a tariff calculation rather than a guaranteed average bill.. These descriptions are useful planning benchmarks; actual charges can change with meter size, usage, sewer averaging, local taxes, drought stages, or account-specific fees.
Wastewater and sewer calculation
The active CWS record and Cal Water Bayshore tariff cover potable water service. The reviewed Cal Water materials do not publish a San Carlos wastewater formula, winter-average method, or percentage tie-in. Sewer charges, if applicable, are billed or administered separately by the responsible local sewer agency or property arrangement; customers should use that agency's sewer account rules rather than infer wastewater charges from the Cal Water meter bill.
Meter and infrastructure notes
The San Carlos system is metered and the Bayshore district reads meters monthly. Cal Water's 2025 planning materials say it is piloting automatic meter reading and advanced metering infrastructure in several districts, but they do not state that AMR or AMI has been deployed to every San Carlos account. Customers should use the bill's read dates, meter number, and current/previous reads; the portal provides usage history, while Cal Water can confirm the exact meter technology and leak-alert capability for an individual premise.
Emergency water support
Report a leak or water emergency
The Bayshore district main and after-hours number is 1-650-558-7800. Use it for urgent leaks, breaks, outages, or water-system emergencies; the Cal Water leak page also provides an online report form for public leaks and water waste. For a customer-side plumbing leak, shut the house valve when safe and arrange repair promptly.
Official starting point
Choose the right next step
Reading this profile
A practical reference for San Carlos and vicinity, San Mateo County
California Water Service - San Carlos System is listed here as a private investor-owned utility. The profile separates account actions—such as paying a bill or requesting service—from explanatory material about rates, meters, wastewater, leaks, and delinquency.
Because utility rules can vary by account class, meter size, service address, billing date, and local ordinance, treat the published bill and current provider website as the final authority. Use this profile to locate the correct channel and prepare better questions for customer service.
If your issue is urgent, start with the provider’s emergency number or official payment route rather than waiting for an email response. Keep a written record of calls, confirmation numbers, notice dates, and documents you submit.