Water Recycling Frequently Asked Questions

Why use recycled water?

Where is it used now?

How safe is recycled water?

Where can we use recycled water?

What about using recycled water for residential gardens?

Why use recycled water?

Using recycled water can help reduce the pressure on our drinking water supplies and, in some cases, offers additional environmental benefits. For example, treated wastewater contains nutrients that can be recycled by plants, reducing fertiliser costs and making it perfect for irrigation.

Reuse in Western Australia has increased significantly in recent years, due mainly to the construction of the Kwinana Water Recycling Plant (KWRP).  This supplies 17 million litres per day of highly treated recycled water to industries in the Kwinana Industrial Strip.  This was a major step forward for water recycling for the Perth Metropolitan area. Investigations are underway to expand the capacity of the KWRP plant.

There is a high level of water recycling in country areas of Western Australia, mostly for irrigation of fields, parks, school grounds and golf courses, with more than 60 water recycling schemes across the State.  In most cases the recycled wastewater is used directly from the treatment plant following disinfection.  In Geraldton and Mandurah it is used indirectly via infiltration to the groundwater. Other uses in regional areas include irrigation of a vineyard in Mt Barker, woodlot irrigation at many south-west towns including Albany, Kemerton, Margaret River and Dunsborough and industrial uses in Pinjarra.

Where is it used now?

Reuse in Western Australia has increased significantly in recent years, due mainly to the construction of the Kwinana Water Reclamation Plant (KWRP). This supplies 17 million litres per day  of highly treated recycled water to industries in the Kwinana Industrial Strip. This was a major step forward for water recycling for the Perth Metropolitan area. The KWRP plant is approaching capacity and when this occurs recycling for Western Australia will be at about 14%. Investigations are underway to expand the capacity of the KWRP plant.

There is a high level of water recycling in country areas of Western Australia, mostly for irrigation of fields, parks, school grounds and golf courses. In most cases the recycled wastewater is used directly from the treatment plant following disinfection. In Geraldton and Mandurah it is used indirectly via infiltration to the groundwater. Other uses in regional areas include irrigation of a vineyard in Mt Barker, woodlot irrigation at many south-west towns including Albany, Kemerton, Margaret River and Dunsborough and industrial uses in Pinjarra.

How safe is recycled water?

Many people are concerned about health implications if they come into contact with recycled water - if they are accidentally sprayed by reticulation or receive a cut from a sporting accident or walk on wet grass. Wherever recycled water is used, strict Health Department guidelines for water quality and management including watering times must be met.

Before being recycled wastewater is treated to stringent health regulations to meet a standard that is appropriate for its intended use. When reused for a beneficial purpose this water is known as "recycled water". Currently, in Perth most treated wastewater is returned to the marine environment via ocean outlets.  A small amount is returned to the environment via infiltration/evaporation ponds.

Extensive work is carried out to ensure that recycled water schemes are designed and monitored to minimise any environmental impact. Each scheme will require the approval of the Department of the Environment.

Where can we use recycled water?

Recycled water can be used for various functions, including:

  • to flush toilets and wash clothes (greywater only);
  • to water ovals, gardens and golf courses;
  • in industrial processes;
  • to grow crops;
  • topping up superficial aquifers, wetlands and lakes; and 
  • to recharge groundwater from which drinking water is drawn.

In each case, the recycled water would be treated to a quality suitable for its intended use, for example recycled water for irrigation could not be used for recharging groundwater drinking supplies as this has more stringent health and environmental requirements.

Industry

Suitable industries include manufacturing, mining, mineral processing and power generation. Generally recycled water can be used for cooling or process water.

Perth's major industrial area is in Kwinana where the top 10 users of scheme water consume 7.3 gigalitres each year. The Kwinana Water Recycling Plant is the first major water recycling scheme for Perth.  Water is treated by reverse osmosis and used in industrial processes.

Operation began in November 2004.  At full capacity the plant supplies 6 gigalitres of low salinity recycled water to industry.  It is planned the plant will be expanded to meet future demand for water in the Kwinana Industrial Area.

The co-location of this large industrial area and the Woodman Point wastewater treatment plant (which supplies water to KWRP) is fortuitous as it ensure the costs of recycling remain low, however this situation is rare.

Playing fields, parks and golf courses

Broome Golf Course is now green thanks to water recycling

Playing fields, parks and golf courses use large quantities of water - usually groundwater. Replacing this supply with recycled water cam be practical and offers significant benefits.

In country WA recycled water has been used for over 40 years to irrigate playing fields, parks and golf courses. In fact there are currently over 60 schemes of this type in the State.


Horticulture/ Agriculture

Horticulture and agriculture are significant users of water. Using recycled water for irrigation is possible and could provide significant reuse of the nutrients contained in recycled water. Recycled water is currently used to irrigate horticultural and orchard crops on the Northern Adelaide Plains in South Australia, and in many other parts of the world.

Woodlots

Using recycled water to grow tree crops is another common practice. Recycled water is used to irrigate a tree farm north of Albany. These trees demonstrated higher growth rates than those that are rain-fed and timber harvesters reported that quality of the wood was exceptional.

Groundwater recharge

There are various methods to recharge groundwater, whether the superficial aquifer or the deep confined aquifers, with recycled water.  This is sometimes also known as Managed Aquifer recharge.

The intent is to increase water storage in the aquifer, to make more water available for irrigation and other uses and also to preserve water levels in wetlands that are maintained by groundwater. Groundwater recharge may also be used to mitigate or control saltwater intrusion into coastal aquifers.

Perth is well suited for this practice with sandy soils and well defined confined and superficial aquifers.

The Water Corporation has undertaken research into the different replenishment methods, including recent trials in partnership with CSIRO at the Halls Head wastewater treatment plant in Mandurah and at the CSIRO headquaters in Floreat.

From 2010 to 2012, the Water Corporation will also conduct the Groundwater Replenishment Trial at the Beenyup Wastewater Treatment Plant in Craigie.

What about using recycled water for residential gardens?

The Corporation is focusing its efforts on developing water recycling schemes where the recycled water will be used in place of drinking-quality water, therefore, making this drinking-quality water available for uses which require a high quality of water such as bathing and drinking.

Although some new developments have introduced a third pipe scheme providing recycled water for gardens, it is unlikely that this would be adopted in existing suburbs given the massive cost and disruption to communities in laying new pipes in every street and re-plumbing every home.