Too much lead in rain water tanks prompts scientists to discourage drinking from them

New research by scientists from Monash University and the CSIRO has raised concern over the use of rainwater tanks.

Threats of water shortages and a genuine desire to do their bit to conserve resources has meant many Australians have installed tanks in their yards to collect rainwater.

However this latest research implies the tanks could in fact present a health issue because the researchers have found that many are often contaminated with high levels of lead and other heavy metals such as aluminium and iron.

The joint project conducted in a Melbourne suburban area has revealed a third of the Melbourne suburban rainwater tanks studied have lead levels which exceed the Australian drinking water guidelines - one household's tank contained lead concentrations that exceeded safe drinking levels by 35 times.

Senior researcher Dr Grace Mitchell from Monash University, says traces of other heavy metals such as cadmium were also found but the main concern is to isolate the source of the lead.

Dr. Mitchell says the source could be environmental or atmospheric and associated with the dust that blows around an urban area.

Dr. Mitchell suggests the lead could come from lead flashing on roofs or pipes that haven't been properly coated, or industrial processes which may be emitting lead - until relatively recently lead was also present in petrol.

According to Dr. Mitchell the lead will not have an effect if people do not drink the water; if the water is drunk the main concern then is the developmental delays associated with lead in children.

Lead levels and the Australian drinking water guidelines are set at a level which assumes a person is drinking a reasonable amount of the water each day but most households only used the tank water for washing, watering the garden and flushing toilets.

Dr. Mitchell says only a few households reported drinking from their lead-contaminated tanks and none of those tested, had blood-lead levels which were a concern.

According to the Australian Bureau of Statistics 20 per cent of homes now have rainwater tanks, and most have been installed for conservation reasons and others to service properties not connected to mains water.

The highest number is in South Australia with almost half of all its households sourcing some water from tanks.

Dr. Mitchell suggests people drink only mains water and use their tank water for washing or watering and regularly flush and test their tank water.

However in many rural areas tank water is all there is and many Australians living in the bush have no other choice.

For them the research will be of concern particularly if they have young children.