Alternatives to desalinated water

Friday, February 23, 2007

What are the alternatives to the "last resort" plan — the $1.9 billion desalination plant at Kurnell — that NSW Premier Morris Iemma's Labor government is so keen to get moving on?

One obvious one is to recycle storm water and grey water (from washing machines and bathrooms), something that would require a significant investment of funds into new infrastructure, but which would be a more sustainable use of energy and resources than building the desalination plant.

Rainwater harvesting is being heavily promoted by the Greens in their campaign for the March 24 NSW elections. They argue that household rainwater tanks would significantly reduce the city's demand on water supplies.

According to NSW Greens MP Ian Cohen, "multiplying the number of Sydney homes with water tanks effectively moves the catchment to the coast". The Greens want the rebate on tanks to be increased, and will push the government to allow homeowners to pay via instalments added to their quarterly water bill rather than as an upfront cost.

While such reforms head in a good direction, they can only ever be a partial solution to the problem. This is because many Sydney residencies couldn't physically accommodate a rainwater tank, and many residents would simply not be able to afford one, even if subsidised. (How many flat owners do you know who would be willing to fork out for tanks for their tenants?)

The Greens are also urging Labor to fund local water capture and storage projects, such as the old Balmain reservoir under Gladstone Park and the collection of rainwater from the roof of the Leichhardt Oval grandstand. They are calling for people's welfare and the health of the rivers to "be put ahead of the profits of agribusiness".

These would be important reforms, but any comprehensive plan would have to address the water use of the biggest water users in Australia — industry and agriculture. Between them, they account for the use of about 90% of the current water supply of 22,186 billion litres per year, according to the Australian Bureau of Statistics.

The Greens call for "low net water usage industrial processes", an end to inefficient irrigation practices, the development of low water-demand agricultural crops to replace higher demand crops, and for research into planting and watering techniques that minimise water consumption.

But there needs to be a plan to force industry to recycle its waste water. This would go a long way to reduce fresh water use. While subsides should be given to working farmers to recycle and to convert open irrigation channels to below ground irrigation, there should also be a plan drawn up to phase out high water-using crops such as rice and cotton. While groundwater can be used, it has to be in a measured and sustainable way (currently about one third is being pumped to the surface). New dams also have to be placed in better catchment areas.

Currently only about 2% of water used in Sydney is recycled, compared to about 20% in Adelaide. The City of Sydney Council estimates that approximately 70% of all water used in Sydney is piped to sewerage treatment plants before being channelled out into the ocean after negligible treatment.

Water recycling has proven effective in other parts of the world. In California, for example, recycling was chosen over desalination. In Singapore, the government scrapped plans to build six desalination plants to meet the city-state's water needs, building only one after introducing recycled water.

Sara Phillips reported in Cosmos magazine last June reported that Sydney, with 4 million people, gets, on average, 1217 mm of rain a year, Brisbane gets 1146 mm and Perth 773 mm. Compare this to London — city of 7.3 million — which gets 611 mm and has not had water restrictions for 15 years because it recycles its water.

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