What is Backflow Prevention?

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

Back pressure is another way that an undesirable contaminant may enter the potable water supply system. 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 an almost constant risk of overcoming the static water pressure in the piping.

The threat of deadly chemicals in our drinking water is a major problem that cannot be taken lightly. These hazards can be severe with over 10,000 reported cases of backflow contamination each year worldwide. Some cases can be fatal.

Solution

To reduce the risk of contamination, a backflow prevention device must be fitted by law and must be installed in accordance with plumbing and building codes.

As a matter of course, new buildings are now required to install these valves during initial construction. In Sydney however, Sydney Water is undertaking a constant audit of all commercial and industrial properties and are issuing directives for the installation of devices according to the risk factor of the property. This is determined by the nature of the business undertaken on the site. Outside of Sydney, this compliance is administered by local water authorities or local councils.

There are three main categories that need to be considered when establishing what and where a device is fitted in accordance to the risk associated.

Containment
To safeguard the entire property and placed at the main meter assembly.

Zone
To safeguard an area internal of the property.

Individual
To isolate a high risk area from a potable tap on the same line – e.g. kitchen.