Recycled water: understanding the usage patterns and drivers to maximise use by residential customers in Victoria

ABSTRACT

Analysis of typical household consumption of Class A recycled water in Victoria shows that the resource is underutilised, and there is potential to increase use, thereby saving our precious drinking water for consumptive purposes. A joint study with Victorian water corporations found that average household use across Victorian third-pipe customers is approximately 23% of total water use. Compared with a potential 40–45% for allowable end-uses (toilet flushing, washing machine, and outdoor uses such as irrigation, cleaning, and car washing), there is an opportunity equivalent to around 2.2 GL per annum for immediate savings of potable water if usage behaviours were shifted. One striking finding is the potential volume of additional recycled water usage that can be achieved through behavioural change. The study compared observed usage against expected usage from suitable end-uses. This model estimated a current underutilisation of 2.2GL per annum based on the number of connections in 2023 across the service areas. Projecting this underutilisation to future service connections, it is predicted that by 2030, a minimum of 4GL of drinking water savings per year could be achieved and 7GL per year by 2050, if usage behaviours can be changed.