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Recycled water explained

Recycled water is wastewater that has been collected and treated so that it can be used again for a variety of non-drinking purposes.

How is recycled water treated?

Wastewater produced in the area previously serviced by Western Water is transferred from customers' properties to one of seven recycled water plants and treated to a Class A, Class B or Class C standard. Depending on the process used, the treatment period can last anywhere from eight hours (mechanical treatment plant) up to approximately 100 days (lagoon based treatment plant).

Primary stage

The primary stage removes solids as water passes through a screen, preventing large objects such as bottles and plastic bags from entering the rest of the system. Water then passes into a tank where remaining solids sink to the bottom and are removed.

Secondary stage

In the secondary stage, liquid moves into large aeration tanks where oxygen is pumped in to encourage the growth of micro-organisms. These break down organic matter into simple materials such as water and carbon dioxide. A floating sludge separates 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 remaining solids settle to the bottom.

Tertiary stage

Phosphorous is removed during this stage. Phosphorous is a chemical which is often added to detergents. It is harmful to the environment.

Sewage is filtered one last time and remaining solids (biosolids) are removed. The remaining water is disinfected with chlorine. This 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.