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Payment research · dataset 2026.08

Payment options for California Water Service - San Mateo System

This page identifies provider-specific public payment information without accepting payments or asking for account credentials.

Provider-published destination

Official online route identified

Confirm the utility name, service address, balance, processing date, funding method, and final fee on the external page before submitting. US Water Bill Pay cannot see or post the transaction.

Continue to provider-published portal ↗

Provider-specific findings

Payment research for this provider

The compiled notes distinguish confirmed channels from details the public material did not expose. Fields containing only an unavailable-information marker are grouped in the research record below.

Payment platform
Cal Water customer portal (vendor not publicly identified)
Phone payment number
1-888-598-9824
Pay-by-text
Cal Water's PromisePay arrangement service at calwater.promise-pay.com can provide payment-plan reminders by text to residential customers with a past-due balance of at least $50, but the reviewed materials do not describe a general text-to-pay keyword or a standalone San Mateo text-payment enrollment flow. Customers should enroll through the official Cal Water assistance page or customer portal and confirm the sender before following a payment link. Regular bill payment is available through the portal or the automated phone number.
Mail-in payment address
California Water Service, P.O. Box 7229, San Francisco, CA 94120-7229. Include the Cal Water account number on the check or money order, use the payment stub when available, and do not send cash through the mail.
In-person payment
The Bayshore district office serving San Mateo is at 341 North Delaware Street, San Mateo, CA 94401, with posted district hours Monday through Friday, 7:00 a.m. to 7:00 p.m.; Cal Water expressly states that in-person customer service is not available at that location. Customers can use the secure Cal Water office drop box where available, Walmart Bill Pay during the store's normal business hours, or a Western Union pay station. Walmart accepts cash or debit card for Cal Water Bill Pay, requires the full account number, uses WMBP same-day processing, and has a $1,500 transaction limit; Western Union availability and any fee should be confirmed at the location.
Digital payment methods
The Cal Water portal and one-time guest payment support Visa, Mastercard, Discover, debit card, and bank-account/electronic-check payments. Cal Water AutoPay can draw from a bank account, Visa credit or debit card, or Mastercard credit or debit card; the payment-options table also lists Discover for online payment. Walmart Bill Pay accepts cash or debit card, while the available instrument depends on the channel. Apple Pay, Google Pay, and other digital wallets are not identified in the reviewed Cal Water materials.
Online convenience fees
Cal Water's current payment-options table lists no online, one-time online, or phone convenience fee for the standard portal and automated phone channels. Mail payments incur ordinary postage. Western Union's fee is stated as temporarily suspended on the reviewed page, but third-party retail terms can change and should be confirmed before payment.

Directory comparison

Payment-information visibility

MeasureThis providerCaliforniaNational index
Usable payment URL identifiedYes81%73%
Fee or no-fee amount disclosedNo24%15%
Payment fields documented8 of 8——

This comparison measures directory documentation, not payment quality, cost, or provider performance.

Research record

Broad public detail found

8 of 8 fields in this section contain provider-specific public detail in dataset August 1, 2026.

Documented

100%

Primary verification routes

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