Backflow Prevention

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Cross-Connection Control and Backflow Prevention Program Background

What is cross-connection?

A cross-connection is any actual or potential connection between the potable (drinking) water system and any non-potable source or substance that could threaten water quality. Cross-connection control is the management of these connections to protect public health by preventing contamination caused by backflow.

What is backflow?

Under normal conditions, water flows from the public water supply to the consumer’s plumbing system. Backflow is the undesirable reversal of this flow, which can allow contaminants or non-potable substances to enter the drinking water system.

Backflow can occur in two ways:

Why do we need a cross-connection control/backflow prevention program?

The California Water Board Cross-Connection Control Policy Handbook (External Site) requires all public water systems to implement a cross-connection control program. To comply with this requirement, the City of Simi Valley and Ventura County Waterworks District No. 8 (District) developed a Cross-Connection Control Plan (CCCP) with the goal of ensuring backflow prevention assemblies are tested annually and records are maintained. The City of Simi Valley adopted the CCCP on October 6, 2025 under Ordinance No. WWD-19 (PDF)

Customer Support

The State of California requires backflow prevention assemblies to be installed on all properties with hazardous cross-connections to help protect the public water supply. These assemblies must be tested and certified at least once a year to ensure that they are functioning properly. The City of Simi Valley and Ventura County Waterworks District No. 8 (District) partners with Backflow Solutions, Inc. (BSI Online) to administer the backflow program.

You are responsible for hiring a licensed backflow tester to perform the annual test and certification of the backflow assembly. The District and BSI Online do not perform testing. Each year, affected customers will receive a mailed notice when their annual test is due.

Licensed backflow testers can be found using the BSI Online lookup tool (External Site). Enter your Customer Confirmation Number (CCN) located in the top right corner of your mailed notice. Your CCN is required for your backflow tester to properly file your backflow test reports. You may also use this CCN at BSI Online to verify when your backflow test has been filed.