Cross Connection Program

Certified Tester List Link

What is Cross-Connection Control?

A cross connection is any actual or potential physical connection between a potable water line and any pipe, vessel, or machine containing non-potable fluid, solid or gas, such that it has the potential to enter into the potable water system by backflow. 

We are making sure that water used for non-potable purposes (irrigation, industry, chemical dilution, fertigation, etc…) does not contaminate our potable (drinking) water system. The simplest measure we can all take to reduce the risk involves ensuring an air gap exists between the tap or water outlet and the holding tank. For example, always ensure the garden hose is above the flood rim of the janitor bucket or sink. Remember: never leave a garden hose submerged. 

Town of Oliver Bylaw No. 1043
Town of Oliver Bylaw No. 1089 Amendment

What is Backflow?

Backflow is a flow of solid, liquid or gas from any source opposite to the normal direction of flow, back into the potable water supply/system.

There are 2 types of backflow, backsiphonage and backpressure:

Backsiphonage is caused by negative pressure in the supply piping. Some common causes of backsiphonage are:

  1. High velocity in pipelines
  2. Line repair or a break that is lower than a service point
  3. Lowered main pressure due to high water withdrawal rate such as fire fighting or water main flushing
  4. Reduced supply pressure on the suction side of a booster pump

Backpressure is caused whenever a potable system is connected to a non potable supply operating under a higher pressure by means of a pump, boiler, etc… There is a high risk the non potable water may be forced into the potable system whenever these interconnections are not properly protected.

Degree of Hazards

High Hazard

A substance that could pose an immediate health concern because of the risk of death, spread of disease or illness, or injury to the customer if it were introduced into the potable water system.

Low Hazard

A substance that would not impose an immediate health concern, but could result in the water in the purveyor’s system not meeting drinking water standards, or could interfere with the monitoring of water quality.

Where are Cross Connections Found?                                    


Whenever a plumbing fixture is connected to the potable water supply, a potential cross connection exists. Fortunately, many of the plumbing fixtures have built-in backflow protection. Listed below are  commonly found cross connections in our water systems:

  1. Wash basins and service sinks                              
  2. Hose bibs
  3. Irrigation sprinkler systems
  4. Auxiliary water supplies
  5. Laboratory and aspirator equipment                                  
  6. Processing tanks
  7. Boilers
  8. Water recirculation systems
  9. Swimming pools
  10. Solar heat systems
  11. Fire sprinkler systems

Common Testable Backflow Prevention Assemblies

Reduced Pressure Backflow                             Double Check Valve                        Pressure Vacuum Breaker
Assembly (RPBA)                                             Assembly (DCVA)                            Assembly (PVBA)


Web Sites that Offer  Information on Cross Connection Control & Certified Products

CSA Certified Product Listings

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