This project has found that if basic precautions are adopted, waste water from vegetable washing sheds can be re-used, saving many millions of litres of water annually. It is estimated that 4.4 million ML of water is used in Australia every year for washing vegetables, yet very few growers are willing to re-use the water for feat that it may contain plant pathogens, human pathogens such as E. coli or significant residues of agrochemicals. Growers are most concerned about the re-use of waste water used to remove soil from root crops as it is highly coloured and often produces foul odours.

Australia-wide surveys of vegetable farm waste water derived from washing root crops showed that there were very few cases of excessive agrochemical residues but there was a slight increase in levels of plant pathogens, E. coli, nitrates, and phosphorus. The water was shown to be unsuitable for discharge into rivers and streams but could be treated economically and effectively on farm for re-use. The most common agrochemical residues were residual pre-emergent herbicides. Consideration should be given to recent herbicide application history and if recent applications were made, then the water should be tested for herbicide residue concentrations. In some instances, excessive linurom levels in waste water had the potential to harm sensitive crops.

A set of guidelines were developed to assist growers in designing effective waste water treatment systems to remove excess organic matter, plant and human pathogens, and nutrients. Safe re-use of waste water has the benefit of reducing farm costs and the requirement of water from rivers and bores.

This project has been funded by Hort Innovation, using the research and development levies listed below and contributions from the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture.

• Vegetable Fund