By John Radcliffe

Australians are the third-highest users of water in the world after the USA and Canada. By world standards, our drinking water is cheap, costing about $1/ kilolitre while Britain, Belgium and Germany pay nearly $2.50/kl. But Australian cities are finding it increasingly difficult to get enough drinking water.

This was brought forcibly home in Canberra following the impact of the bushfires on water catchments. NSW has said no more dams, is providing more water for the environment and is exploring desalination. Inflow to Perth’s reservoirs has halved since 1974: the city has now realized its groundwater is running low and has committed to desalinating sea-water. Adelaide pumps up to 85% of its water from the River Murray.

Australians use 34% of our domestic water for gardens and another 20% to flush toilets. Even if we needed that much water for gardens and toilets, we don’t need to use drinking water.

Only about 10% of our treated wastewater is re-used for other purposes. The rest finishes up in oceans, rivers and estuaries. In 2004, Sydney reused about 2.5% of its wastewater, Perth 4% and Brisbane 4%. This reuse mainly went to irrigating crops or public parks - little drinking water was saved. Adelaide is recycling 19% due to new schemes to grow high value vegetables and wine grapes outside the city.

There are large recycling opportunities in industry. Bluescope Steel at Wollongong is showing the way, recycling up to 20 Megalitres (ML) a day. In Brisbane, the Amoco-BP refinery is taking up to 13 ML of recycled water daily from the Luggage Point Wastewater Plant, saving the cost of a new pipeline as well as saving drinking water.

Rouse Hill in Sydney is the first major suburb in Australia built with a dual water supply. Drinking water is only used in the kitchen and bathroom, recycled water in the toilet, garden and now, laundries. Similar subdivisions are developing at Aurora in Melbourne and Mawson Lakes in Adelaide.

Recycled stormwater is an attractive option, pioneered in Adelaide by the Salisbury City Council for use in industry and at Mawson Lakes.

New research has improved membrane technologies as a preferred technology for recycling and desalination. However, there is still a challenge in disposing of the saline waste stream that is a by-product. Well-managed wetlands, which can also be amenity features, have value for the natural remediation of wastewater and stormwater.

If the recycled urban wastewater is used for agriculture, there is strong seasonality of demand. If stormwater is used, there is strong seasonality of supply. In either case, storage is required. Surface storage takes large areas of land. Aquifer storage and recovery offers a promising solution where the hydrogeology is right.

Price is an important issue. Rouse Hill showed that, with the recycled water costing only 28 cents/kl while drinking water was 98 cents, residents tended to use more water than people in conventional subdivisions.

Compact on-site recycling plants like those at Melbourne’s Flemington Racecourse and Canberra’s Southwell Park offer further solutions, as do self-contained wastewater recycling units in large apartment and office buildings like those of Tokyo and Los Angeles.

Canberra, Melbourne and Perth have established 20% recycling targets by about 2012.

Quality control of recycled water is crucial: there must be no risk to human health. Through sound R&D it is technically possible to safely recycle water back to the drinking water storages, as Singapore already does. Australian cities like Toowoomba are now exploring these options.

There is no single solution to the water challenge. Communities must together identify the water supply strategies that suit them best. This may involve combinations of household rainwater tanks, catchments with dams, use of groundwater, wastewater recycling, remediated stormwater and desalination.

Water strategies should not be imposed on people. The community must recognise the need for change and take responsibility for the necessary decisions. Recycling has a large role to play in solving Australia’s water challenges.

Dr Radcliffe AM FTSE is a CSIRO Honorary Research Fellow. In 2004, he completed the review Water Recycling in Australia for the Australian Academy of Technological Sciences and Engineering , and in 2005 was appointed a Commissioner of the newly-created National Water Commission.

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