Olivenhain Municipal Water District works diligently to deliver safe and reliable drinking water to its customers. However, some hazardous conditions may exist on customer properties which threaten the safety of the drinking water supply.

What does backflow or cross connection refer to? 
Backflow is a term for unwanted flow of water in the reverse direction of a customer’s water meter.  It can be a serious health risk for the contamination of the potable water supply by a private water system.
A cross-connection is a point in a plumbing system where the potable (drinking) water supply is or can be directly connected to a nonpotable source (water unfit for drinking).

Water systems are designed to have higher pressure than a customer’s system to keep water flowing in the right direction. However, when there is a drop in water main pressure, a reverse flow – or backflow – can occur. This can be caused by incidents such as water main breaks or high demands such as fire fighting. A backflow condition can result in water contamination if hazardous cross-connections exist, regardless of all treatment processes.

     Examples of backflow:

  • A toilet flush cistern and its water supply must be isolated from the toilet bowl.
  • A bucket of soapy water to wash a car should never have a hose from the potable water supply left in it.  If a break occurs in the water line, it could suck that soapy water into the system.

To protect OMWD’S water system from actual or potential cross-connections with customers’ private plumbing systems, backflow prevention devices are required for certain OMWD customers.

What does a backflow device do?
The device prevents back siphonage and backpressure into OMWD’s water supply, protecting the water supply from cross contamination.

Who installs the device?
Most multi-family, commercial, and industrial properties as well as properties with an auxiliary water supply and properties with irrigation meters in OMWD’s service area are required to have a backflow device, specifically a reduced-pressure-assembly backflow device.  It is the responsibility of the customer/water user to install all required assemblies in accordance with OMWD’s Standard Drawings and Specifications. Any approved backflow prevention assembly shall be the property of the water user and OMWD shall have no responsibility or liability for the cost of operation, maintenance, repair, or replacement thereof. The water user shall maintain the physical condition of the backflow prevention assemblies and shall be solely responsible for any claims that may arise from injuries or damages caused by the assemblies

Who inspects the device?
Initial inspections and a backflow assembly test of all approved backflow prevention assemblies shall be performed by OMWD and can be scheduled by calling 760-632-4201 or emailing us.  Thereafter, it shall be the duty of the water user to have certified inspections and operational tests made at least once per year. In instances where OMWD deems the hazard to be great enough, it may require certified inspections at more frequent intervals. These inspections and tests shall be at the expense of the water user, and shall be performed by an approved Certified Backflow Tester.

All installed devices must be tested on an annual basis. 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.

Where can I find additional information?
Cross Connection Control Ordinance 429
Certified Backflow Tester List
Cross-Connection Questionnaire
USC Foundation’s List of Approved Backflow Prevention Assemblies

What can I do at home to prevent backflow?

While single-family residences are not generally required to have a backflow device, you can help prevent backflow contamination by:

  • not leaving hoses attached or submerged in unsafe water such as fertilizer or cleaning solution
  • confirming that anti-siphon type irrigation valves are installed
  • installing a hose bib vacuum breaker

Please note: Many new homes are already equipped with anti-siphon faucets.