Cities as Water Supply Catchments: Risk and health – understanding stormwater quality hazards (Project C1.2)

Overview

Harvesting and reuse of stormwater runoff provides ecosystem services and increases water security. Impediments to the implementation of stormwater harvesting systems are mainly related to concerns regarding potential public health risks. Testing stormwater for micropollutants, toxicity and pathogens is costly and time consuming and has not been undertaken on a large scale, particularly for raw or blended stormwater.

The project aims to characterise the chemical, microbial and toxicological quality of raw and blended stormwater in diverse Australian catchments. Comprehensive water quality testing and characterisation has been conducted and researchers have applied in-vitro bioassays (biological assessments of substances to determine their activity and the effect they have on a living organism) to evaluate toxicity to screen for chemical pollutants. In addition, water quality data has been combined with data from catchment audits to increase knowledge regarding the influence of catchment characteristics on stormwater quality.

Key outcomes

Through studies of urban catchments in Victoria, Queensland and New South Wales the project has shown that urban stormwater in some catchments can have characteristics similar to secondary treated wastewater, with remnants of pathogens found. This is an important finding that informs the selection of stormwater treatment technologies to produce fit-for- purpose water supplies.

Information gained in this project will contribute to the improvement of guidelines for stormwater harvesting and the development of stormwater treatment technologies to provide fit-for- purpose water.

Researchers are developing a report characterising the chemical and microbial qualities of untreated stormwater, and will publish recommendations for assessing risks associated with untreated stormwater including the role of chemical surrogates.