The Stormwater Harvesting and Reuse module is one of the three modules that comprise the second phase of the Australian Guidelines for Water Recycling, which address health and environmental risks associated with water recycling. The stormwater guidelines cover only nonpotable (ie non-drinking water) potential end uses of roofwater and stormwater and extends the scope of Phase 1 of the water recycling guidelines (NRMMC– EPHC–AHMC 2006), which focuses primarily on reuse of wastewater and grey water.
Due to the limited available peer reviewed literature at the time, the Stormwater treatment criteria for public, open-space irrigation was calculated on the basis of the ratio of the mean E. coli concentrations from Table A2.4 and the corresponding concentration in raw sewage from the Phase 1 guidelines. As a result treatment requirements were determined to be less stringent than those in the Phase 1 guidelines (NRMMC–EPHC–AHMC 2006) for wastewater irrigation. The reason for this is that levels of faecal-derived microbial indicators and pathogens in stormwater were calculated to be less than 1% of those found in sewage.
Since the drafting of these guidelines in 2009, there has been significant improvement in the knowledge of water quality risks and variability for stormwater. It is proposed to undertake a state of knowledge review of the currently available data on stormwater quality and risks and use this new information to update and refine the AGWR stormwater module.
26th Jun, 2020