Scientists have discovered the contaminants get sucked into the water supply when there is a leak in the pipe. Many cases of a 'dodgy tummy' could be caused by the water we drink, and not some food we've eaten, says Prof Toby Boxall, an engineer at Sheffield University.
Although water regulators reckon that 99 per cent of our water is always fit to drink, the researchers have discovered groundwater around water pipes can easily get sucked into the public supply when pressure drops after a leak. The groundwater often contains viruses and bacteria from sewage.
Fellow researcher Dr Richard Collins said that the contaminants would be at very low levels by the time they reach our taps, but they would still fail safety tests-and certainly could be enough to cause an upset tummy.
(Source: Journal of Hydraulic Engineering, June 2015; doi: 10.1061/41203(425)55)