Chemical water quality and health risk assessment of urban rainwater tanks

Abstract

There has been strong interest in recent years to use rainwater tanks in urban areas of Australia, as catchments yields become less predictable and urban populations continue to increase. The CRC Water Quality and Treatment is conducting research to assess the quality of water from rainwater tanks in urban and industrial areas of Australia. The aim of this research is to concentrate on tanks where a potable supply exists and to use the data in health risk assessment. Storm event data has shown that discarding the first millimetre of runoff via a first flush device usually does little to substantially reduce the mean concentration of contaminants. First flush devices can also substantially reduce the catch of rainwater tanks. Rain sampling shows that there is some lead in rain, though there may be a greater input from the roof itself. The use of rainwater in hot water systems (HWS) can lead to increases in copper and lead concentrations. The lead concentration from hot water sometimes exceeds the drinking water guidelines. The source of the lead from the roof requires further study.