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Each year Western Water transfers 7000 megalitres of sewage to our seven recycled water plants. After the sewage is treated, most is re-used as Class A, B, or C recycled water, remaining waste is turned into biosolids for approporate re-use. At the recycled water plant, sewage is treated in three stages 'primary', 'secondary' and 'tertiary', to obtain either Class A, B or C recycled water. Depending on the process used, treatment can take anywhere from eight hours to 40 days.
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The primary stage removes solids as the water passes through a screen, which prevents large objects such as bottles and plastic bags from entering the rest of the system.
The water then passes into a tank where the remaining solids sink to the bottom and then they are removed.
In the secondary stage, liquid moves into large aeration tanks, where oxygen is pumped in to encourage micro organisms to grow, which break down the organic matter into simple materials such as water and carbon dioxide. A floating sludge becomes separated from the water during this process and is sent to a sludge digester where it breaks down. This takes about 15 days.
The remaining liquid from the secondary tanks is moved to stabilising tanks, where the left over solids settle to the bottom. During the tertiary stage, phosphorous, a chemical often added to detergents that is harmful the environment, is removed.
The sewage is then filtered one last time, where remaining solids (biosolids) are removed and the remaining product is disinfected with chlorine. The purified water is then pumped into a shallow holding tank, where sunlight penetrates the water killing remaining bacteria.
Once this process is complete the water is recycled or discharged into the environment. A Fact Sheet called Help Protect our Waterways can be downloaded for more information.
Spills Safety
If there is sewage flowing into your yard from the gully trap or a sewage spill due to a break in a pipe, it is advised that you avoid contact and telephone Western Water on 1300 650 425 or 13WATER (1392837) or call a private plumber immediately.
If you notice a blockage within your sewage system firstly, determine whether it is internal or external. If a constant flow is seen coming from the gully trap (normally located near an outside wall of the building), this indicates the blockage is external. This is a Western Water issue. If this occurs, Western Water will notify the relevant depot staff to visit your property.
If the flow is intermittent and is only noticed when a washing machine, toilet or shower is in use then this usually signifies an internal problem and a qualified plumber should be contacted immediately.
More Information
Biosolids
Recycled Water
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