bhiggins@dailyadvertiser.com.auA CHARLES Sturt University study has found the potentially dangerous bacteria E.coli in a majority of rural water tanks.The pilot study conducted by microbiology lecturer Andrea Crampton surveyed almost 50 farms from across the Riverina and 54 per cent exceeded the Australian Drink Water Guidelines.E.coli was the main bacteria found in the study, finding its way into the water system through bird and possum droppings.A secondary study is now underway into rural residents' attitude to water quality with the belief tank water does not have the chemical levels of city water and also helps build the immune system.NSW Health is now hoping to establish a larger scale study with a public forum to be held early next year.Dr Crampton said while relatively small, the study had resulted in some important findings."We are still assessing some of the health risks associated with E.coli but importantly we also looked for salmonella and traces of lead and they were miniscule," she said."Contamination comes largely from people not cleaning their gutters and roofs and when rain comes, those toxins flush into the water source."