They may not be the most glamourous of scientific instruments, but tampons could help experts clean up polluted rivers. Engineers believe the super absorbent properties of tampons could be used to detect pipes that shunt sewage into streams instead of treatment plants. They found that the cotton products absorb chemicals commonly used on toilet paper, laundry detergents and shampoos, which glow under UV light, meaning that they could shed light on previously undetectable misplumbed pathways. Engineers believe the super absorbent properties of tampons could be used to detect pipes that shunt sewage into streams instead of treatment plants. Here, a discharge pipe dumps raw sewage into a river . It’s estimated that around five per cent of homes in the UK have pipes that are misconnected, causing them to leak sewage. Professor David Lerner, who led the study at the University of Sheffield's Faculty of Engineering, explained: ‘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. ‘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’ But now his team have shown that tampons can glow in ultra-violet (UV) light, because they absorb chemicals found in products containing ‘optical brighteners’ which are used to whiten and brighten colours. Experts think tampons (pictured left) could be a cheap solution to detecting pollutants in rivers. On the right,  Professor Lerner tests for sewage pollution in a stream in Sheffield, UK, using a conductivity and temperature meter - a more expensive but less effective method than using tampons and UV lighting . Tampons absorb chemicals commonly used on toilet paper, laundry detergents (pictured with a stock image) and shampoos, which glow under UV light, meaning that they could shed light on previously undetectable mis-plumbed pathways . Engineers have shown that tampons can glow in ultra-violet (UV) light, because they absorb chemicals found in products containing ‘optical brighteners’ which are used to whiten and brighten colours. Optical brighteners are found in toilet paper, laundry detergents and shampoos. Lab trials determined that just five seconds exposure in 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 – enabled a tampon to glow for 30 days. Therefore, if a tampon is dunked in a river and glows under UV afterwards, experts can be sure there are pollutants in it. By using this technique at the opening of different pipes, they can trace the source of the sewage to certain households so that pipes dumping sewage into rivers can be redirected. When tampons are suspended in water contaminated by even very small amounts of detergents or sewage, they will pick up these ‘optical brighteners’ and glow. ‘The main difficulty with detecting sewage pollution by searching for optical brighteners is finding cotton that does not already contain these chemicals,’ Professor Lerner said. ‘That's why tampons, being explicitly untreated, provide such a neat solution. Our new method may be unconventional - but it's cheap and it works.’ Lab trials determined that just five seconds exposure in 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 – enabled a tampon to glow for 30 days. 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. The scientists found that nine of the tampons glowed, confirming the presence of optical brighteners - and therefore sewage pollution. 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. This enabled them 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. A visual inspection in one area immediately revealed a house where both a sink and soil stack were connected to the wrong sewer, according to the results of the study, which were published in Water and Environment Journal. 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. This image shows a 'scum' caused by detergent in the Peak District National Park . 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. Here, fluorescent powders glow under UV light . Professor Lerner said: ‘Often the only way to be sure a house is misconnected is through a dye test - putting dye down a sink or toilet and seeing where the coloured water appears in the sewer.’ ‘It's clearly impractical for water companies to do this for all the households they supply, but by working back from where pollution is identified and narrowing it down to a particular section of the network, the final step of identifying the source then becomes feasible.’ Pollutants found in domestic waste water change the bacterial and invertebrate life in rivers, encouraging pollutant tolerant species and leading to the build-up of 'sewage fungus', which is visible as a grey lining to the river bed. Waste water discharges can also carry pathogens such as norovirus. Most misconnected households are unaware they are discharging their waste water into the wrong system and - once it has been identified - immediately rectify the problem. Local authorities do have the power to complete the work and charge it back to the householder, but in practice, this power is rarely used. Now that Professor Lerner has proved his method works in practice in the field, he hopes to trial it at a larger scale to identify all the sources of sewage pollution on the Bradford Beck, the river which runs through the city of Bradford.
Engineers at the University of Sheffield made the discovery .
Tampons glow under UV light when they have absorbed detergent .
This enables experts to work out where pollution is coming from .
Innovation could stop sewage being accidently shunted into rivers .