Image: Chris Southwood, City of Sydney
The City of Sydney is taking a bold step to reduce its reliance on drinking water for street cleaning by utilising runoff water filtered from kidney dialysis machines at Royal Prince Alfred Hospital.
The council’s plan to use filtered runoff tanks rather than Sydney drinking water is expected to save 1.5 million litres of water every year.
What is dialysis?
Dialysis is a medical procedure that cleans the blood when the kidneys are not functioning properly, acting as filters to remove waste and excess fluid. There are two main types of dialysis:
Haemodialysis: This involves extracting blood from the body, cleaning it through a dialysis machine, and returning it. This treatment typically occurs three times a week for 4 to 5 hours each session.
Peritoneal Dialysis: This method utilises the lining of the abdomen, known as the peritoneum, as a natural filter. Treatments can occur up to four times a day.
Why is water from dialysis machines different?
Around 50 dialysis machines at Royal Prince Alfred Hospital operate for up to 14 hours a day, each requiring approximately 500 litres of ultrapure water per treatment.
To ensure no bacteria is present during these critical procedures, a reverse osmosis unit generates the necessary ultrapure water.
During the purification process, excess runoff is collected and stored in two on-site tanks, which were designed and built as part of the redevelopment of the Professor Marie Bashir Centre in 2020.
The City of Sydney’s latest initiative reflects the city’s commitment to environmentally responsible practices, with “wasted” water now being collected to be used by street washers.
The “reject” water collected from Royal Prince Alfred Hospital will now be used for council cleaning tasks, including hosing off footpaths and removing graffiti.
Sydney’s water conservation efforts
Lord Mayor of Sydney Clover Moore emphasised the importance of water conservation, stating “Water is our most precious resource and finding ways to better manage it is crucial to Sydney’s resilience. This is increasingly important as the climate crisis lengthens periods of drought.”
“Not only does this collaboration mean there is more drinking water available, the filtered supply is great for street cleaning because it has low levels of particles, calcium and magnesium – that means it’s less likely to leave residue and streaking, is less abrasive on road and footpath surfaces, and reduces equipment scaling,” she said.
The surplus water from dialysis is collected in two large onsite tanks, each holding 10,000 litres. The City of Sydney then uses this water to fill its cleaning trucks, resulting in an estimated savings of 30,000 litres per week.
“By collecting the water from Royal Prince Alfred, we are also reducing emissions and travel time for our trucks, which don’t have to return to depots in Alexandria or Ultimo to refill after cleaning the streets,” Moore said.
According to the City of Sydney, their collaboration with the Sydney Local Health District enables access to an alternative water source. This initiative allows both organisations to enhance their water sustainability efforts, while also reducing their environmental impact.
