Cross-Connection and Backflow

Olivenhain Municipal Water District works diligently to deliver safe and reliable drinking water to our customers. 

Conditions may exist on customer properties that could pose a threat to the safety or quality of OMWD’s drinking water supply. As such, our cross-connection specialists conduct hazard assessments to identify and reduce these risks, helping to protect your drinking water.

To provide an additional safeguard against potential risks from private plumbing systems, OMWD requires certain customers to install backflow prevention devices at their meter.

What do cross-connection and backflow refer to? 

A cross-connection is any point where the drinking water supply could come into contact with another substance, such as chemicals, liquids, or non-potable water. Cross-connections can compromise water quality and safety.

Backflow is the unwanted flow of water in the reverse direction of its normal flow towards a customer’s property. It can be a serious health risk if a private water system contaminates the potable water supply.

Water distribution systems are designed to have higher water pressure than a customer’s private plumbing to keep water flowing in the right direction. If there is a significant drop in water pressure in one of OMWD’s main pipelines, a reverse flow, or backflow, from a customer’s property could occur.

A water main break could cause a drop in water pressure. High demands in water use, such as those required for firefighting, can also cause a drop in water pressure. If unprotected cross-connections exist on a customer’s property, backflow during a drop in water pressure can lead to water contamination.

What are ways to prevent backflow?

• Design irrigation systems with backflow prevention in mind. Install pressure vacuum breakers or anti-siphon control valves to protect against contamination from fertilizers or pesticides.
• All hose bibbs should have a vacuum breaker or anti-siphon device. This way, a hose submerged in a bucket of soapy water or a swimming pool will not suck that soapy or pool water into your drinking water system if water pressure drops significantly.
• Have a certified professional inspect and test backflow prevention devices each year to confirm that they are functioning properly.

What does a backflow prevention device do?

A backflow prevention device stops the reverse flow of water from a customer’s property into OMWD’s public water supply. This protects the community’s drinking water from potential cross-contamination.

Who is required to have a backflow protection device?

OMWD requires backflow prevention devices (specifically, reduced-pressure principle assemblies) for most multi-family, commercial, industrial, and agricultural properties. Additionally, OMWD requires backflow prevention devices for properties with fire sprinkler systems, auxiliary water supplies (such as ponds or wells), irrigation meters, or livestock on the premises.

Who installs and maintains the device?

It is the customer’s responsibility to install all required devices outlined in OMWD’s Standard Specifications and Drawings.

Any backflow prevention device is the property of the water user. OMWD has no responsibility or liability for the cost of operation, maintenance, repair, or replacement of such devices. The water user must maintain the physical condition of any backflow prevention devices. Additionally, the customer is solely responsible for any claims that may arise from injuries or damages caused by the devices.

Who inspects the device?

OMWD will perform the initial inspection and testing of all newly installed backflow prevention devices at the meter.  Call 760-632-4201 or email us to schedule. After that, the water user must have a certified tester inspect and test these devices at least once per year.

In instances where OMWD deems the hazard to be great enough, more frequent certified inspections and testing will be required. These inspections and tests will be at the expense of the water user.

Ensuring devices are working properly helps safeguard OMWD’s water system. Each year, customers will receive a reminder notice along with a certified list of testers. Failure to have the device tested could result in the termination of service.

Additional Resources

• Cross-Connection Control Ordinance 529
• Certified Backflow Tester List
• Cross-Connection Questionnaire
• USC Foundation’s List of Approved Backflow Prevention Assemblies
• State Water Resources Control Board’s Cross-Connection Control Policy Handbook
• US Environmental Protection Agency’s Cross-Connection Control Manual

For questions or to report concerns, please call 760-632-4201 or email us.