Cross-Connection Survey and Webinar

At San José Municipal Water System (Muni Water), providing clean and safe drinking water to every home and business within our service area is our top priority. To help us maintain these high standards, we are conducting a brief survey and hosting an informative webinar.

Cross-Connection Survey: 

Complete the 5-minute questionnaire by June 30, 2026 to help identify any special plumbing or activities that may pose a potential risk of contamination to our public drinking water system and your service line. Take our Cross-Connection Survey today. 

Cross-Connection Control Webinar:

If you have questions about the Cross-Connection Survey or want to learn more about the Muni Water’s Cross-Connection Control Program and the State Water Board requirements, attend our virtual webinar. 

• Date: June 9, 2026
• Time: 6 p.m. - 7 p.m.
• Registration link: bit.ly/Cross-ConnectionWebinar

WHAT IS A BACKFLOW?

Backflow is the undesirable or unintended reversal of flow of water and/or liquids, gases, or other substances from the customer’s onsite plumbing back into the public drinking water system. Backflow can occur when there is a sudden decrease of pressure in the distribution system (such as from a water main break) or when the pressure in a customer's onsite plumbing is made to be higher than the distribution system pressure.

Backflow prevention assemblies stop our water supply from possible contamination by residential and commercial sources. Properly installed and maintained assemblies, devices, or methods provide protection against the threat posed by many conditions typically found in an onsite plumbing system.

WHAT IS A CROSS-CONNECTION?

A cross-connection is an interconnection between drinking water from a public water system and a non-drinking water source (like a private groundwater well) through any actual or potential connection.

How can contamination occur?

Contamination may occur when pressure changes cause unsafe water or substances to enter the drinking water system through unprotected cross-connections. Air gaps, backflow prevention assemblies, and other devices are used to protect against backflow at cross-connections.

Helpful Tips For Residential Customers

Without the proper protection, something as simple as a garden hose has the potential to contaminate or pollute the drinking water lines in your house. Muni Water recommends that homeowners install hose bib vacuum breakers on all hose bibs. You can purchase them at most plumbing and hardware stores.

TO REPORT A BACKFLOW INCIDENT, LEAKING BACKFLOW PREVENTION ASSEMBLY, OR POTENTIAL CROSS-CONNECTION, YOU MAY REACH US BY:

• Phone: (408) 277-3671
• Email: backflow@sanjoseca.gov
• Using the online Backflow Incident or Potential Cross-Connection Complaint Form

ANNUAL TESTING

Federal and State laws require water utilities to protect public water systems from contamination or pollution due to cross-connections and backflows into the distribution system. To ensure safety of our drinking water supply, Muni Water requires annual testing of backflow prevention devices installed on water service lines. Muni Water staff sends notices to customers two months prior to when their backflow prevention assemblies are due for testing. The notice includes the test due date along with a copy of the test report(s).

For more information on the customer and backflow tester responsibilities, please refer to the requirements for testing and maintenance of backflow prevention assemblies (last updated January 2026).

Only Backflow Prevention Assembly Testers certified with the American Water Works Association (AWWA) and in good standing with Muni Water are allowed to test backflow prevention assemblies within Muni Water’s service area. Please email the Backflow Prevention team at Backflow@sanjoseca.gov to request an updated list of registered backflow preventor testing companies before having your backflow tested.

• To become a certified backflow tester, visit the American Water Works Association homepage.
• To become a Muni Water registered backflow tester, e-mail: Backflow@sanjoseca.gov.

Reduced Pressure Principle Backflow Assembly