Cross Connection Control

Cross Connection Control
“Backflow” means the undesirable reversal of flow of water or other substances through a cross connection into the public water system or consumer's potable (drinking) water system.

When this happens, contamination of your drinking water can occur. Backflow conditions may occur due to a drop in line pressure in the water main, which can happen due to use of hydrants for fire fighting, water main break, high usage or backpressure.

A “cross connection” is any potential or actual connection (piping or hose) between a water system and a source of contamination.  Cross connection control refers to systems and devices that prevent backflow contamination due to cross connections.

Washington Administrative Code WAC 246-290-490 establishes rules for the implementation of cross connection control programs.  Silverdale Water District administers a stringent cross connection control program to protect your drinking water supply as it travels through our infrastructure to your water meter.  But after it goes through the meter, the owner of a premises may need to implement additional protection.

Here are some common examples of cross connection hazards that need to be protected by using a backflow preventer:



Fire sprinkler system
lawn irrigation systems
Auxiliary water supply (wells)
hot tubs/spas
swimming pools
hose bibs/garden hose

carbonation equipment
film processors
x-ray machines
dental equipment
etching tanks

Note: toilets and sinks have an air gap separation for backflow protection

If you have questions regarding cross connection control, please contact us at or (360) 447-3500.

Types of Cross Connection Control for Backflow Protection
  • An Approved Air Gap Separation
  • Mechanical Assemblies used in the prevention of backflow are separated into three types:
  • Pressure Vacuum Breaker Assemblies (PVBA) and Spill-Resistant Pressure Breaker Assemblies (SVBA)
  • Mechanical Devices used in the prevention of backflow include:
    • Atmospheric Vacuum Breaker (AVB)
    • Hose Bib Vacuum Breaker device (HBVB), also known as a Hose Connection Vacuum Breaker 
    • Dual Check with Atmospheric Vent, also known as a Backflow Preventer with Intermediate vent
    • Dual Check Backflow Preventer
    • Residential Meter Check

Testing Backflow Assemblies
Backflow Assemblies must be tested at the time of installation, annually after installation, after a backflow incident, and after any repairs have been made by a Certified Tester.

If an assembly is relocated and/or reinstalled it must be retested. Anytime a backflow assembly is tested, a test report needs to be submitted to Silverdale Water District at