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101 Collins St, Melbourne, VIC, 3000


101 Collins St is among the tallest buildings in Melbourne, with 83,000 square metres of office space accommodating approximately 4,000 office workers.

Water Use:

Toilet flushing, tenants’ use and wash basins previously accounted for 70% of the building’s water use. Although dual-flush toilets are becoming increasingly common in Melbourne’s commercial and industrial buildings, a number of buildings still have inefficient 11 litre single-flush or 11/6 litre dual-flush toilets.


Having already improved water efficiency in the building’s cooling towers, management committed to doing the same with its toilets. To achieve this, new water-efficient 6/3 litre dual-flush toilets were installed in the building’s 44 tenanted floors.

Pressure ratio valves have been used to maintain the water pressure in all toilets, and computer-based monitoring of the system has been integrated into the maintenance program, making leaks easily identifiable and quick to fix. To complement this, 101 Collins St switched to a less fibrous toilet paper, which is more suitable for toilets with minimal flush volumes, and began a behavioural change campaign to alert tenants to the changes.

The toilet upgrade has not only improved water efficiency, but has helped contribute to the overall sustainability of the building’s operations. Careful planning has ensured workplace disruptions were minimised by carrying out the toilet retrofits after hours and on weekends.


By retrofitting 6/3 litre toilets, 101 Collins St is now at the forefront of water-efficient commercial office spaces. The project was anticipated to save a total of 14 million litres of drinking water each year, helping the building to exceed the 2007 Melbourne water retailer industry best practice benchmark for commercial office water usage.

Total Project Cost: