A cross connection is any point where an external system is connected to a potable water supply. Such connections will usually require a “cross connection device” that prevents water from flowing back to its source. For sprinkler systems, cross connection devices are required to protect your municipality’s drinking water supply from contaminants such as fertilizers or pesticides.
Backflow can be caused by a drop in pressure at the potable water source (siphonage) or an increase in pressure in an external system (backpressure). In either case, backflow usually goes unnoticed. We need to be certain that cross connection devices work properly, or a minor source of contamination can become a major issue over time.
It is the testing of the device used to protect your municipality’s potable water supply from backflow contamination. In Calgary, Alberta it is required by the water purveyor for these devices to be tested every year. A cross connection on an irrigation system must be tested yearly and before the irrigation system is turned on.
They are required annually wherever there is a cross connection that could potentially contaminate the water supply. Underground sprinkler systems are a prime example, as dirt and chemicals such as herbicides or fertilizers can enter the system unnoticed over time, without causing any other issues. The City of Calgary requires you to have your sprinkler system’s cross connection tested before the system is activated each year.
These tests are mandated by section 39.3e of the City of Calgary’s Water Utility Bylaw. This reflects a similar mandate in the National Plumbing Code of Canada, as do similar bylaws in countless other municipalities.
A sprinkler cross connection is the point at which the sprinkler system hooks up to the potable water supply. That is why a backflow prevention device (typically a Double Check Valve Assembly) is needed at that location. Backflow preventers are mandatory, nationwide, at any cross connection between a potable water supply and an external system, as per the National Plumbing Code of Canada. DCVAs are the recommended backflow preventer for most modern residential irrigation systems, as outlined in CSA B64.10-17.
The most common cross connection is a hose attached to a garden tap. If this garden tap is hooked up to an irrigation mainline, it should have a cross connection device installed where the irrigation water line hooks up to the potable water supply. If it is just a regular garden tap, it should have a hose bib vacuum breaker on it.