Recharge water was harvested for drinking from urban stormwater.

Recharge: turning stormwater into drinking water

A South Australian project demonstrates that water, currently left to flow down our gutters, can be treated to produce drinking water.

• 16 September 2009 | Updated 14 October 2011

• Project process
• Project achievements
• Project benefits
• Partners to 'Recharge'

An Aquifer Storage, Transfer and Recovery (ASTR) project has shown that harvested urban stormwater can be injected into a brackish aquifer and recovered and treated to produce high quality water of drinking standard.

Project process

The water, labelled ‘Recharge’, was harvested for drinking from urban stormwater that was collected from the 1 620 hectare (ha) residential and light industrial area of Salisbury, South Australia.

The water was first treated by passing it through a reed bed. This allows for the particles to settle and removal of sorbed constituents. It was then injected via wells into a limestone aquifer, 160 metres below ground, for storage.

Traditional Aquifer Storage and Recovery (ASR) uses the same well for injection and recovery.

The ASTR concept involves using separate injection and recovery wells to extend residence time and allow months of natural slow filtration through the aquifer.

The water for ‘Recharge’ was extracted after more than a hundred megalitres of fresh water had already been recovered for industrial and municipal irrigation and residential non-potable supplies. It contains a blend of 95 per cent stormwater from 2007 and 2008 and five per cent residual native groundwater (resident for 10 000 years).

‘Recharge’ retains a slight mineral flavour because the native groundwater was originally brackish and too salty even for irrigation supplies. 

Recovered water was rigorously tested and found to meet drinking water health criteria. To further ensure drinking water safety, the recovered water was given aeration, activated carbon filtration, microfiltration and ultraviolet disinfection. It also received ozone disinfection.

Project achievements

The project demonstrates that stormwater can be harvested and passively treated, using initially brackish aquifers and recovered to meet drinking water quality on a single sampling occasion.

When managed aquifer recharge is supplemented with engineered treatments via replicable procedures that comply with the National Water Quality Management Strategy, water quality can be produced that is fit for drinking.  

’Recharge’ signifies the potential value of urban stormwater as a resource. Further research is required to show whether this can be reliably done on an ongoing basis for normal water supplies, taking account of all the hazards likely to be present in an urban catchment. Results to date look very encouraging.

Project benefits

Once proven, use of stormwater can allow for a cost-effective expansion of urban water supplies.

Its use as part of a diverse water supply portfolio approach has a number of benefits, such as:

• reducing pressure on river catchments that would otherwise be used for source water
• detaining and capturing stormwater before it flows out to sea reduces suspended solids and other contaminants entering urban coastal waters
• a low carbon footprint compared with other common alternative supplies
• averting the economic, social and environmental costs of building new dams for water storage
• avoiding the costs of duplicating distribution systems if stormwater can be sustainably harvested for drinking supplies
• saving money on alternative water supplies where the costs of aquifer and engineered treatments of stormwater are substantially less than costs of, for example, desalination
• exploiting existing resources to help address water shortages in urban areas.

Partners to 'Recharge'

'Recharge' was produced by CSIRO Water for a Healthy Country Flagship program and City of Salisbury from water derived from the ASTR site.

Read more about the Water for a Healthy Country Flagship.