A visual inspection in one area immediately revealed a house where both a sink and soil stack were connected to the wrong sewer.

They were able to successfully isolate the sections of each network where the sewage originated, narrowing down the households which would need to be inspected in more detail. With the help of Yorkshire Water, the team followed the pipe network back from four of the nine polluted outlets they'd identified, dipping a tampon in at each manhole to see where the sewage was entering the system. Nine of the tampons glowed, confirming the presence of optical brighteners - and therefore sewage pollution. The technique was then trialled in the field by suspending tampons for three days in sixteen surface water outlets running into streams and rivers in Sheffield and then testing the tampons under UV light. When a tampon was dipped for just five seconds into a solution containing 0.01ml of detergent per litre of water - over 300 times more dilute than would be expected in a surface water pipe - the optical brighteners could be identified immediately and continued to be visible for the next 30 days. The study, funded through the Engineering and Physical Sciences Research Council, used laboratory trials to determine how much detergent would need to be in the water to be picked up by the tampon test. Our new method may be unconventional - but it's cheap and it works.' That's why tampons, being explicitly untreated, provide such a neat solution. 'The main difficulty with detecting sewage pollution by searching for optical brighteners is finding cotton that does not already contain these chemicals. Unfortunately, it's very difficult to detect where this is happening, as the discharge is intermittent, can't always be seen with the naked eye and existing tests are complex and expensive. Professor David Lerner who led the study, explains: 'More than a million homes have their waste water incorrectly connected into the surface water network, which means their sewage is being discharged into a river, rather than going to a treatment plant. The findings are published on March 31 in the Water and Environment Journal. Using a mixture of laboratory tests and field trials, the team from the University of Sheffield's Faculty of Engineering have shown that when tampons are suspended in water contaminated by even very small amounts of detergents or sewage, they will pick up optical brighteners and glow under UV light.

Glow in the dark tampons