AS the Greater Sydney population continues to expand, the North Richmond Water Filtration Project will have an increased role to play in treating sewage to top-up the Hawkesbury’s drinking water.
This is according to Western Sydney University’s Dr Ian Wright – an expert in water conservation based at the School of Science and Health – who said many people did not realise that Sydney already relied on recycled sewage to top-up its water supplies.
“Drinking recycled sewage is a very confronting topic. But even in Australia’s biggest city – Sydney – it is an important part of the water supply,” he said.
Dr Wright said the townships of Goulburn, Lithgow, Moss Vale, Mittagong and Bowral all discharge their treated sewage into the catchment rivers that supply the city’s drinking water to Warragamba Dam.
Hawkesbury’s tap water comes from a number of sources including Warragamba and the Upper Nepean catchments, and the Hawkesbury River via the North Richmond Water Filtration Project, according to the WaterNSW website.
Dr Wright said there are also sewage treatment plants located in the Blue Mountains, Penrith, Wallacia and West Camden, all of which discharge their treated sewage into the Hawkesbury-Nepean River.
“The North Richmond Water Filtration Plant extracts and treats this water to supply some parts of north-western Sydney,” he said.
Dr Wright said this method of ‘indirect potable reuse’ of treated sewage is common, and the water is highly treated to ensure it meets Australian drinking water guidelines.
But Greater Sydney is forecast to gain another 1.74 million residents in the next 18 years, meaning there will be an increased demand for water.
Dr Wright said while no Australian urban water supply currently uses ‘direct potable reuse’ – which involves treated sewage being transferred directly into the city’s water source, without it first being mixed in a dam, river or reservoir – this method will need to be considered if population numbers continue to rise as forecast.
“Available data is limited, but in the recent dry summer I estimate that treated sewage comprised about 20 per cent of the Hawkesbury-Nepean flow in the North Richmond area,” Dr Wright said.
“Much of Sydney’s population growth will be in western Sydney, one of the most rapidly growing urban populations in Australia. And this will result in more treated sewage, and urban runoff, contributing to the Hawkesbury-Nepean River flow.”
Visit the WaterNSW website for more information about where your town water comes from.