Drinking Recycled Stormwater

A few months back, there was some discussion on this blog regarding opportunities for the use of urban stormwater as a drinking water supply (see comments from Mark at the bottom of this post). An article from the Adelaide Advertiser this week, points to the likelihood of such a strategy being undertaken on a large scale in Australia sometime in the future.

The City of Salisbury in northern Adelaide is where most of the activity has been focused. A decade ago, the city began to investigate potential means of eliminating the flow of polluted stormwater into the environmentally sensitive Barker Inlet of Gulf St. Vincent. The Inlet is a significant fish nursery which supports the majority of South Australia’s fishing industry.

The key strategy adopted was the creation of wetlands for stormwater treatment. Some of this treated water is now reused for a variety of non-potable purposes in the region. The scheme has been very successful and there has been great interest in expanding it in order to be able to reclaim larger volumes of water.

Among the main challenges has been the need to overcome the seasonal variability between available water supply and demand. Naturally there is more stormwater available during the wetter months, but these wet months are when irrigation users (in particular) least require it.

To address this need for large-scale water storage, the CSIRO has spent more than a decade researching a process known as aquifer storage and recovery (ASR). This involves preparing the water to a suitable quality whereby it can be safely used to recharge a depleted aquifer and then recovered at a later time when required. The general concept is nicely summarised in the following figure from CSIRO Land & Water.



As the above figure indicates, ASR can be used for appropriately-treated reclaimed water from any source including stormwater and municipal sewage. Under suitable conditions, it can even have a significant benefit in terms of further improving the water quality during the process.

Given these benefits, it may be no surprise that the Government of South Australia and the National Water Commission appear to agree that there is great potential for Adelaide to use urban stormwater reclaimed by ASR as a future drinking-water supply.

The article from The Adelaide Advertiser appears below.

I’d be grateful for your thoughts or comments...


Stormwater for drinking
The Advertiser (Adelaide)
October 22, 2007
By Cara Jenkin

ADELAIDE residents will be drinking recycled stormwater as traditional water supplies continue to dwindle, says the National Water Commission.

South Australia's representative on the commission Dr John Radcliffe says treated stormwater will form part of SA Water's metropolitan supply in the future to ensure long-term water security in the city.

Dr Radcliffe said governments had traditionally treated stormwater as a "hazard" and as waste which could not be used.

He said stormwater should instead be seen as a resource.

"People naturally feel a little concerned about drinking water that doesn't fall off the hillsides, but some of these hillsides aren't that pristine," he said.

"All water is recycled water, that's the hydrological cycle."

Stormwater is already collected, stored and used for irrigation purposes in parks across Adelaide.

A world-first trial to treat stormwater naturally in underground aquifers to a standard suitable for human consumption is now under way at Parafield.

Dr Radcliffe said the trial was one reason why South Australia was more advanced in stormwater reuse than elsewhere in Australia. "One has to look at all water resources that are around and there is no perfect resource for a particular circumstance," he said.

"One of the benefits is that (treated stormwater) has a lot less salinity than is found in Adelaide tap water."

Treated stormwater will be added to the mains water pipes and dispersed among households.

The water will supplement existing sources but figures on what portion of existing supply could be supplemented are yet to be researched.

Draft guidelines on the use of recycled water for drinking have been developed by the National Water Commission.

They are expected to be endorsed by state water ministers, including SA Water Security minister Karlene Maywald, when they meet to discuss the guidelines early next year.