Water Recycling

Salisbury's water recycling solutions set an example used to showcase best practice urban stormwater management to audiences worldwide. The links in this section will assist you in understanding water management techniques that have been implemented and how Salisbury has achieved this.

The City of Salisbury receives an average annual rainfall of 430mm, which results in some 33GL of annual stormwater run-off from catchments within its jurisdiction.

Catchments are critically analysed using models such as ‘Watercress' to determine stormwater run-off patterns (volume & flow intensities) in response to rainfall events. The quality of the urban stormwater flows are also analysed to determine treatment processes required for reuse.

Detention basins (temporary stormwater storage areas) are then able to be sized and designed to capture stormwater during rain events, providing essential flood mitigation objectives and opportunities to harvest stormwater.

Detention basins often incorporate gross pollutant traps to remove floating debris and litter, and a sedimentation area that allows much of the suspended solids in the stormwater to settle out of suspension. Detention basins are fitted with automated controlled release mechanisms to enable the release of stormwater at an optimal flow rate for treatment.

Once released from controlled detention, stormwater is treated through constructed wetlands which remove nutrients, heavy metals and other pollutants to produce stormwater quality suitable for recycling. In addition to wetlands, other treatment mechanisms such as bio-retention systems are also currently being trialled.

Hydro-geological investigations are undertaken to determine the characteristics of the aquifers in the area. Cleansed stormwater from wetlands is pumped into, and later recovered from, aquifers by a process known as aquifer storage and recovery (ASR) With most of the rainfall in Salisbury received during the winter months (May to August), ASR provides the storage necessary to be able to provide recycled stormwater all year round.

Recycled stormwater is extracted from the aquifer using submersible bore pumps. The recovered water is pumped to storage tanks which are part of automated distribution pump stations that deliver the recycled stormwater to customers via a purple pipe recycled water reticulation network.