Affluent effluent: growing vegetables with wastewater in Melbourne, Australia—a wealthy but bone-dry city

Water scarcity in Australia has become a significant challenge for all water users and water reuse is now a critical component of Melbourne’s response to this water crisis, particularly for food production. While most vegetable production occurs in a large-scale commercial environment, there is a significant proportion produced in backyards. With the introduction of severe water restrictions, commercial vegetable production now relies heavily on high quality Class A reclaimed water, while households have turned to the use of greywater. While there are many benefits of wastewater reuse, there are also many potential risks to plant, environmental and human health. A quantitative microbial risk assessment of the two systems was conducted to evaluate the human health risks associated with both large-scale and backyard reuse of water for vegetable irrigation. This preliminary model suggests that for irrigation with typical greywater, the annual infection probability for enteric viruses is >10^?4, even after a two week period of no irrigation with greywater. The human annual enteric virus risk from Class A reclaimed water was much lower.