Backflow testing & repair in Menlo Park, CA
Menlo Park (San Mateo County) gets its water from 2 suppliers, and the one on your water bill sets your backflow rules:
- Menlo Park Municipal Water: you hire a certified tester. We test, file the results with Menlo Park Municipal Water, and repair failed devices.
- California Water Service – Bear Gulch District: you hire a certified tester. We test, file the results with Cal Water Bear Gulch, and repair failed devices.
- County
- San Mateo County
- Water suppliers
- Menlo Park Municipal Water; California Water Service – Bear Gulch District
- Annual test
- Menlo Park Municipal Water: owner hires a certified tester and Cal Water Bear Gulch: owner hires a certified tester
- Our price
- $199 per device ($25 off for new customers), or from $180/year on a plan
- ZIP codes
- 94025
Menlo Park Municipal Water rules for Menlo Park customers
- San Mateo County Environmental Health manages the City’s program and mails the account holder a letter when a test is due.
- Test results go to San Mateo County within 10 days of the test.
Source: Menlo Park Municipal Water backflow program (official page), checked October 17, 2026.
Rules for new and replacement devices in Menlo Park
Menlo Park Municipal Water
- Devices are installed above ground after the water meter, typically no more than five feet from the property line.
- Installing a backflow device needs a City building permit; the annual test does not.
Source: Menlo Park Municipal Water backflow program (official page).
Cal Water Bear Gulch
- Only approved, testable backflow prevention assemblies may be installed at the water meter.
- Air gaps must also be inspected every year.
- The assembly installed must be the type Cal Water’s local cross-connection specialist specifies.
Source: Cal Water Bear Gulch backflow program (official page).
Installing or replacing a device takes a licensed plumbing contractor, usually with a permit. We can refer you to one we trust, test the new device once it’s in, and make minor repairs to existing ones.
Backflow questions from Menlo Park property owners
Which water supplier serves Menlo Park?
Menlo Park is split between Menlo Park Municipal Water and California Water Service – Bear Gulch District. Your water bill names your supplier, and its notice sets your backflow rules.
Who tests backflow devices for Menlo Park Municipal Water customers in Menlo Park?
Testing must be done by a certified backflow tester on San Mateo County’s list, on installation and at least once a year after that.
Who tests backflow devices for Cal Water Bear Gulch customers in Menlo Park?
Property owners are responsible for their backflow assemblies, which Cal Water requires to be inspected and tested every year by a certified backflow prevention assembly tester.
When is the backflow test due in Menlo Park for Menlo Park Municipal Water customers?
San Mateo County Environmental Health manages the City’s program and mails the account holder a letter when a test is due.