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Macarthur Fact Sheet
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The Macarthur Water Supply Project
The Macarthur Water Filtration plant, which supplies water to over 200,000 Sydney Water customers in the Camden, Campbelltown and Wollondilly areas, was built to improve water quality. Completed in 1995, the plant is jointly owned by a consortium comprising United Utilities Australia and Transfield which provided finance, design and construction services as well as on-going operations and maintenance.
United Utilities Australia operates and maintains the plant on behalf of the consortium. After 25 years, Sydney Water has the option to buy the plant or renegotiate another operations contract. Capable of treating up to 265 megalitres of water a day, the plant was required to overcome variable water quality problems in Sydney’s south west. During storms, fast flowing creeks which feed local water storages, pick up sediments and make the raw water turbid. In addition water from the catchments has a high iron content which can discolour water and stain washing. The filtration process removes sediments and colour, eliminating these as sources of water quality problems.
The treatment plant operates to an exceptionally high standard, making it one of the most efficient in Australia. Raw (untreated) water is sourced from Broughton’s Pass Weir, a local beauty spot located directly downstream from Cataract Dam.
Tunnels also connect the weir to the Nepean, Cordeaux and Avon dams. The raw water is elevated of 130mk via low and high lift pumps to raw water storage tanks on site. From here, the water flows by gravity through the filtration plant. At the treatment plant, coagulants or thickeners such as Ferric Chloride and Polydadmac are added to the water so that particles of sediment will join together or floc, facilitating removal. This material, sludge, is collected and dried on-site prior to removal. It can be used for landfill or reused in other ways such as adding colour to bricks. The water passes on to filtration tanks where it passes through coal and sand filters.
During the treatment process lime and carbon dioxide are also added to control pH during the process and for final correction. Chlorine is dosed between the filters and the treated water storage tanks for post-filtration primary disinfection and into treated water gravity main. Ammonia is also dosed into the main where it converts the free chlorine residual to a chloramine residual which is a longer lasting disinfectant. Fluoride is also added for dental protection. A relatively small volume of treated water is used locally. Most gravitates some 15km to reservoirs supplying the fast-growing Campbelltown and Narellan areas.