Recycling not the 'magic bullet' in water supply

There is no one "˜magic bullet' for securing Australia's future water supplies and all options on the water menu should be considered, according to agricultural scientist and Commissioner of the National Water Commission, Dr John Radcliffe.

"Since the introduction of the National Water Initiative (NWI) from 2004, water recycling has gained a high public profile as a source of urban water, accompanied by a polarisation between political opponents on the merits of wastewater recycling versus desalination," said Dr Radcliffe.

Writing in the latest edition of ATSE Focus, the quarterly magazine of the Academy of Technological Sciences and Engineering (ATSE), Dr Radcliffe discusses how the best solution should involve a consideration of all water source options including dams, rivers, lakes and groundwater basins, recycling wastewater, harvesting and remediating urban stormwater, desalinating of seawater and reducing demand by more efficient water use.

"All options should initially be on the table to identify what is the best set for each community," said Dr Radcliffe, adding that location and demand, community ownership and a triple bottom line approach should drive water supply choices, with the overriding requirement that water be fit for purpose.

In the article Dr Radcliffe discusses:

• Catchment dams are expensive; many of the best sites have already been used; land and construction costs are high; lead times are long; and downstream environmental flows need to be maintained.
• Groundwater can be an attractive source but replenishment may be very slow, resulting in a risk of over-extraction for short-term convenience.
• Desalination is energy-expensive and may have a high greenhouse gas emission cost, although the membrane technology costs are reducing.
• Wastewater recycling uses similar membrane technology and — although technically there is very little risk in putting recycled water straight into the supply scheme — the community is not sanguine about the prospect.

"Separation of water and sewage supplies has arguably been the biggest single contribution ever made to public health and there can be an inherent resistance to wastewater recycling based on the "˜toilet to tap' perception, the disgust factor," he said.

"The community must have faith in the competence and credibility of the water supplier if recycled water is to be incorporated into a drinking water system, even though there are numerous examples of unplanned indirect wastewater recycling."

"Knowledge that further natural remediation can occur within a large water body such as a river or reservoir gives comfort to users. The ability for this function to be also performed in groundwater basins is currently being researched in Perth and Adelaide," says Dr Radcliffe.