Quantifying water quality characteristics of stormwater

Recycled stormwater has a range of possible uses that have different levels and types of human exposure. Before systems to collect and re-use stormwater are established it is important to identify and measure the risk stormwater poses to human health and the environment. This research collected samples from two sites after 12 rainfall events. Low levels of herbicides and other chemicals were found in all samples, lower than the threshold considered safe by the Australian Guidelines for Drinking Water (ADWG), but higher than levels Environment Protection Agencies permit for injection into natural acquifers. These low levels probably caused some of the toxic effects observed in the in vitro cell culture tests. There were very low levels of pathogens that can infect humans in some samples. It was concluded that stormwater should be treated before being re-used for a range of applications which might include replenishing acquifers and that it would be sensible to survey stormwater catchments and in some cases treat stormwater from specific contaminated sites because this would be more cost-effective than treating the entire stormwater outflow.