The South Australian Water Corporation reports that greater Adelaide currently uses approximately 140 GL of water each year (averaged over five years) from mains drinking water supply (when not on water restrictions), and that regional SA uses approximately 70 GL each year. These figures are slightly different from those used in the Audit.460 This water is provided through the metropolitan Adelaide system, which consists of more than 9,000 km of pipeline, more than 120 large storage tanks, 59 pumping stations, nine reservoirs and six water treatment plants.461 With its relatively low rainfall and long, dry summers, SA depends heavily on water from the River Murray to meet its requirements. In an average year, the River Murray supplies about 40 per cent of the state's urban water needs,462 while in dry years this can increase to as much as 90 per cent.
For many decades SA relied on using unfiltered water from the River Murray. However, SA Water now provides 98 per cent of the population with high quality filtered water which meets or exceeds the standards of the Australian Drinking Water Guidelines.
As part of SA's Water for Good Plan to secure water for the future, the SA Government has built a seawater desalination plant at Port Stanvac, south of Adelaide, to ensure drinking water is available even in times of drought. The plant has the ability to produce up to 100 GL of drinking water per year,463 or up to half of Adelaide's current drinking water needs.
SA Water collects and treats about 95 GL of wastewater in Adelaide and about 100 GL state-wide every year. SA Water's metropolitan wastewater system serves Adelaide's population through more than 8,700 km of sewer pipes and three major wastewater treatment plants: Bolivar, Glenelg and Christies Beach, and a small plant at Aldinga. It manages 19 of the 20 wastewater treatment plants, with the Victor Harbor plant privately operated under contract. Adelaide's three major metropolitan WWTPs process more than 250 ML of wastewater a day. Since 1997-98, SA Water has more than tripled the percentage of wastewater being recycled across SA.
Under initiatives contained in Water for Good Plan, greater Adelaide's water supply for drinking and non-drinking purposes is projected to meet demand beyond 2031. The Water for Good Plan contemplates meeting future demand with new water sources, and through the better management of the current water sources (including water saving measures, as distinct from water restrictions). The major contributors to meeting future demand are:
■ desalination, especially for small regional townships where water quality is identified as being an issue; and
■ stormwater harvesting and the use of recycled wastewater as an important supply source, especially for irrigation and industry.
As part of SA Water's Long Term Plan for Eyre Peninsula, investigations are underway regarding the construction of a desalination plant for Eyre Peninsula.
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460. South Australian Water Corporation (2014), p. 81
461. South Australian Water Corporation (2014), p. 80
462. South Australian Water Corporation (2014), p. 80
463. South Australian Water Corporation (2014), p. 23