Cross Connection Control


To provide information to the public on Cross Connection: how it occurs, how to control it, and guidance on the selection and installation of backflow preventers.

Bylaw 2005-02 is currently under construction.

References and Background

What is a Cross Connection?

In water supply systems, water is normally maintained at a significant pressure to enable water to flow from the tap, shower, etc. When pressure falls or is reduced, as may happen if a water main bursts or there is unexpectedly high demand on the water system, the reduced pressure in the pipe may allow contaminated water from the ground, from storage or from other sources to be drawn up into the system.

Points at which a potable (drinking water) system connects with a non-potable water system are called cross connections.

There are two types of backflow: back-pressure and back-siphonage.

Back-pressure occurs when the pressure in a private water system is greater than the pressure in the City's water supply system. Back pressure can force an undesirable contaminant to enter potable water piping. Sources of back pressure may be pumps in the water distribution system, boilers, heat exchanging equipment, or power washing equipment. In these cases there may be a risk of overcoming the static water pressure in the piping. To reduce the risk of contamination, a backflow preventer must be fitted. A backflow preventer is also important when potentially toxic chemicals are used, for instance for commericial/industrial descaling (boilers) or when bleaches are used for residential power washing.

Back-siphonage is the reversal of normal flow. This is caused by a reduction in the pressure in the local water supply system which can be caused by nearby fire-fighting or water main break. Back-siphonage can cause contaiminated water to be pulled into the water supply system.

Cross Connection Devices

Air gap: The least expensive and most effective way to provide backflow prevention is to provide an air gap. A simple example is the space between a wall mounted faucet and the sink rim (this space is the air gap). Water can easily flow from the faucet into the sink, but there is no way that water can flow from the sink into the faucet without modifying the system. This arrangement will prevent any contaiminants in the sink from flowing into the potable water system by siphonage.

Vacuum breaker: A vacuum breaker typically contains a plastic disc that is pressed forward by water supply pressure, and covers smal vent holes. Should the supply pressure drop, the disc springs back, opening the vent holes which let in outside air, preventing backflow of water.

Double Check Valve Assembly: A double check valve assembly (DCVA) consists of two check valves assembled in series. This employs two operating principles: firstly one check valave will still act, even if the other is jammed wide open. Secondly the closure of one valve reduces the pressure differential across the other, allowing a more reliable seal and avoiding even minor leakage. The double check valve assembly is suitable for prevention of back pressure and back siphonage, but is not suitable for high hazard applications. It is commonly used on irrigation, fire sprinkler, and boiler systems. If the hazard is higher, such as using antifreeze in the fire sprinkler system, then a more reliable check valve such as reduced pressure backflow assembly must be used.

Reduced Pressure Backflow Assembly: This device consists of two independent check valves, plumbed in series, with a pressure monitored chamber between. The chamber is maintained at a pressure that is lower thant the water supply pressure, but high enough to maintain downstream pressure. The reduced pressure is guaranteed by a differential pressure relief valve, which automatically relieves excess pressure in the chamber by discharging to a drain. Because certain combinations of check valve failure and/or system backpressure cause the relief valve to discharge, the device must be mounted in a location where the drain will not become flooded.

The City of Penticton's Cross Connection Control Program

The City of Penticton is working to ensure all properties are provided with premise isolation. Premise isolation is the isolation of a property's private water system from the City's potable water system. In addition, we are examining the potential for contamination within the building to its occupants from fire, sprinklers, irrigation, air conditioning, boiler, and other systems.

  • We will conduct a survey of your building facility to identify possible cross connections.
  • Once complete, you have 6 months in which to hire a certified plumber/tester to install the device(s) and provide the initial test forms to the City. A Plumbing Permit is required for installation of backflow preventers.
  • To ensure that backflow prevention devices are functioning properly, a certified tester must then test them annually, and also if they are repaired, relocated, or replaced. 

As of April 1, 2017, BSI Online is maintaining our backflow test records.  They will be sending testing notices to water customers as well as collecting results from testing companies.

Water Customers - Need to know if your results have been submitted? 

Testing Companies – Need to register with BSI Online?

If you have any questions about the program, call Lynelle Arsenault at 604-492-0163 or email

Please note:

As of January 1st, 2020, testing companies will pay a filing fee of $15.95 for every test report submitted.

Partial List of Certified Testers

Backflow Prevention Testers.pdf [PDF - 98 KB]

Need More Information?

Please contact the Cross Connection Control Coordinator at 250-490-2562.