People often complain that backflow prevention is costly, and it is this presumption that leads to incorrect protection being applied. That is often because the installer either does not understand the types of devices and their protection levels, or it is just easier to install a Reduced Pressure Zone device as it is the highest level of protection. Peter McLennan, CEO of the Backflow Prevention Association of Australia Inc. (BPAA), explains.

We all know that there are two types of backflow events – backpressure and backsiphonage – but does the installer consider which type is likely at each installation? They should.

Let’s consider the humble hose tap or hose cock. There are usually two on every house and millions more used throughout Australia.

How many of these are protected from a backsiphonage event?

To understand this more, what is backsiphonage and how does it occur? Backsiphonage is the result of supply pressure being lower than that of the system it feeds. This may occur when a supply is interrupted or drained down.

The two most common causes of backsiphonage are water being drawn out of the water main by fire appliances taking water for firefighting and watermain breaks.

Every time a water main breaks, a backsiphonage event occurs. This does not happen much, I hear you say; well it does!

Evidence suggests that Sydney Water experiences over 4,000 watermain breaks per year. That means alone, and each will result in a backsiphonage event. there are around 11 water main breaks per day in Sydney

In the USA, WASDA, the Water & Sewer Distributors of America, suggest that a watermain breaks every two minutes across the USA. That is 720 watermain breaks a day, with every instance initiating a backsiphonage event.

So let’s focus again on the humble hose tap. Hoses get left dangling in drains, swimming pools, laundry tubs, cleaners sinks and worse, so if a backsiphonage event occurs and there is no backflow protection on the tap, where does the siphoned, contaminated water end up? In your drinking water, that’s where.

The National Construction Code, Volume Three, the Plumbing Code of Australia identifies hose cocks as points of cross-connection to the drinking water, and as such require backflow protection in line with the hazard, or potential hazard that could be cross-connected to the hose cock. In most cases it will likely be a low hazard, but if the hose cock is within 18m of a hazardous potential cross-connection, the hose cock must have backflow protection suitable for that hazard.

For more information on the National Construction Code (NCC) cross-connection requirements visit the NCC.

The solution can be as simple as an inexpensive hose connection vacuum breaker affixed to the outlet thread of the hose tap. They sell for around $25 and provide the backsiphonage protection needed to protect your drinking water. They are readily available from plumbing outlets or contact your licensed plumber.

If you have a backflow prevention question, contact us at the Backflow Prevention Association of Australia at bpaaoffice@bpaa.org.au and we will get back to you.