Where do we get our water?
We source our water from a combination of the River Murray, local catchments, groundwater, recycled stormwater, treated wastewater, local rainwater and desalinated water.
Our rainfall, including how much and where this falls, determines the relative contribution of the various water sources.
The ABS Water Account 2015–16 distinguishes between 4 categories of water supply (Figure 33):
- Self-extracted – water extracted directly from the environment in accordance with licences and permits (including desalination)
- Distributed – water supplied by SA Water, irrigation trusts and local councils
- Reused – treated wastewater or stormwater
- Regulated discharge – water discharged to the environment after use, for example treated wastewater.
At full capacity, the 10 reservoirs located throughout the Mount Lofty Ranges catchment area can hold almost 200 GL of water. This is a little less than a year's supply for metropolitan Adelaide. The main reservoirs in the Mount Lofty Ranges, in order of capacity, are Mount Bold 46.5 GL, South Para 44.4 GL, Myponga 27.6 GL, Little Para 20.9 GL, Kangaroo Creek 18.7 GL, Millbrook 15.7 GL, and Happy Valley 12.7 GL.
The remaining three Barossa, Hope Valley and Warren all hold less than 5 GL of water each. The primary water supply for metropolitan Adelaide relies on inflows into the Mount Lofty Ranges reservoirs as well as water pumped from the River Murray.
Water for regional SA is provided by a combination of pumping from the River Murray, small rural reservoirs, local dams and groundwater bores. Regional reservoirs are located at Baroota, Beetaloo, Blue Lake, Bundaleer, Middle River and Tod River.
The 100-GL Adelaide Desalination Plant was completed in 2012 to provide a climate-independent source of water for metropolitan Adelaide. It supplements the state’s traditional sources, such as the Mount Lofty Ranges reservoirs and the River Murray.
The combination of these resources provides the necessary water security to underpin economic and population growth to 2050. In recent years, the plant operated at minimum production mode, contributing on average 30 ML per day for 9 months of the year (about 8 GL per year). This approach has been verified as prudent and efficient by the Essential Services Commission of SA in its determination of the SA Water Regulatory Business Proposal 2016–2020
Stormwater and treated wastewater
South Australia’s stormwater harvesting capacity is 22 GL (with a target of 35 GL by 2025), and treated wastewater capacity is almost 74 GL. Household rainwater tanks provide about 20 GL of SA’s water capacity.
Groundwater is the world’s largest source of freshwater. In Australia, groundwater provides about 40% of the flow in streams and helps to earn Australia about $34 billion a year from mining, food production and manufacturing.
Groundwater collects in underground waterbodies known as aquifers. South Australia has 32 drinking water supply systems drawing water from aquifers as their primary source of domestic water. Most of these are located in the South East, Eyre Peninsula and the northern region of the state. The Blue Lake, which supplies the city of Mount Gambier, is a volcanic crater containing groundwater from regional aquifer systems.
The relative amounts of water used from particular sources varies between sectors. Figure 34 depicts water sources used for farming, and shows the relatively large quantity coming from groundwater.