According to a report from Brunel University London, deadly bacteria in drinking water storage tanks — the kind found on roofs or in public building basements — is often overlooked by traditional health and safety tests.
Despite being regularly tested for dangerous pathogenic bacteria such as E.coli and Legionnaires’ disease, researchers determined that samples of the water are generally taken from the top of cold water storage tanks instead of from the bottom. As such, the research team believes that samples taken from the top of the drinking water tanks are 40 percent less likely to cause concern than those samples taken from the bottom.
"These results call into question the reliability of present measures used to protect the public from waterborne pathogenic diseases, including Legionella," said Aji Peter, a Ph.D. student from Brunel's Institute of Environment, Health and Societies, who carried out the research.
Because they can often be a source of repeated bacterial contamination, current regulations require that water samples from water storage tanks regularly be taken from beneath the ball valve at the top of the tank. However, scientists are now suggesting that water from the far end of the tank — water that is likely to house more bacteria-feeding sediment and water that is warmer — should be sampled and tested as well.
"Given the disparity between measurements taken at different ends of the tanks, monitoring at the far end would provide a much more accurate indication of microbiological contamination. This would allow appropriate precautions to be taken to protect the public from waterborne pathogenic diseases, including Legionnaires' disease," said Peter.
The research is published in the journal PLoS ONE.