This is a Smart Water Fund Project

Steriliser Water Conservation

Project Date: 31 December 2005
Project Status: Complete
Research Organisation: Western Health
Project Number: 1008

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The Challenge

Western Health operates three hospitals in Melbourne's western suburbs, offering a broad range of healthcare services.

Operating 24-hours a day, the Western, Williamstown and Sunshine Hospitals have a combined water usage of 580 kilolitres a day in their bathrooms, laundry, kitchen, cleaning and sterilisation areas.

The Facilities Management Department, which services all three hospitals, took up the challenge to reduce the amount of water used by Western Health without compromising the quality of care provided.

The Project

The Central Sterile Supply Department is responsible for cleaning and sterilising contaminated medical instruments and packaging them for reuse. This service is performed with a machine called a Hi Pre-vacuum steriliser. Western Health has nine of the sterilising machines located across three hospitals.

The machines use large amounts of water in the form of steam to sterilise the instruments. At the end of the process the steam leaves the steriliser at 80ºC and must be cooled using a cold water condenser before it can be released into the sewer.

To create a sterile environment, the machines are vacuum sealed using a liquid ring pump that also uses a significant amount of water. Each 35 minute cycle of the steriliser can produce as much as 770 litres of wastewater.

Western Health looked at two options to reuse this wastewater.

The first option was to store and reuse the water to flush toilets. Further investigation into this option, however, revealed a number of issues including:

  • space requirements and storage problems with respect to Legionella
  • existing infrastructure and building design which would create redirection problems; and
  • concerns from City West Water about the quality of waste water.

The second option was to modify each steriliser to use chilled water. The machines could then be connected to the hospital's existing reticulated air-conditioning systems.

The systems operate by circulating chilled water throughout the buildings on a closed loop circuit. Each steriliser operates using the chilled water, after which the wastewater is returned to the central cooling unit, ready for reuse.

It was found that both options saved approximately similar amounts of water. However in light of the number of concerns raised with regard to recycling water for toilet flushing, the Department moved to implement the chilled water option. To ensure patient safety, the machines were modified, connected and tested one at a time to ensure they worked effectively.

The Outcome

Lessons Learnt

By connecting the sterilisation machines to an existing air-conditioning system, the hospitals expect to save over 20 million litres of water a year.

Engineering staff at one hospital office have noticed an immediate difference.

"The staff could hear wastewater running down the pipe outside their building 24 hours a day," said Cecil D'Cruz, Director of Facilities Management and overseer of the Smart Water Fund project. "Now they don't hear anything."

The project has also encouraged Western Health to look for additional ways to save water.

"We realised the flow rates for some of our showers were extraordinarily high – upwards of 22 litres per minute," said Mr D'Cruz.

"We've now put new water restrictors in place, and we're down to the recommended level of between nine to twelve litres per minute."

The Benefits

The project has reduced the hospitals' water bill and sewerage costs with a saving of $24,950 expected per year.

As a bonus, the cost savings associated with the project can be directed to enhance the delivery of care across Western Health hospitals.

Following the success of the project, several hospitals have contacted Western Health and are looking to implement similar programs at their facilities.

Mr D'Cruz believes there are numerous opportunities for health facilities to connect to existing recycled water systems as well as implementing new methods of using wastewater.

"I encourage all health facilities to think about what they can do to save water when investing in new and existing equipment," said Mr D'Cruz.

For all Smart Water Fund Project enquiries please contact swfinfo@melbournewater.com.au

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