Water & Wastewater Treatment

WWT December 2017

Water & Wastewater Treatment Magazine

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Page 16 of 39

www.wwtonline.co.uk | WWT | XXXX 20XX | 17 The rights and wrongs of misconnections The Works D omestic misconnections, in which household wastewater ends up in the surface drainage system rather than the sewers, are a nationally significant water problem. Whether the result of ignorance, carelessness or sloppy workmanship, hundreds of thousands of toilets, sinks, washing machines or dishwashers are incorrectly connected into drains and channels that are intended to receive clean rainwater. It has been estimated by Defra that between 0.6% and 2.0% of households in the UK – or 150,000 to 500,000 households - may have some sort of misconnection. The most commonly misconnected appliances are washing machines (35%), sinks (20%) and dishwashers (10%), but 5% of instances involve a toilet being misconnected; cross-connections below ground can also be responsible for sewage mixing with surface water. This waste ends up untreated in watercourses or beaches, impacting the environment and potentially public health. Nobody quite knows how much pollution in total is caused by "DIY is the only unregulated trade industry, so anybody can go to their local building supplies shop, pick up some pipework and modify any drainage they want on their home," says Broadbent. "Most misconnections are above ground, although there are a proportion which are below ground which have been done either through error or convenience by building contractors, and the clients are ignorant of it." While misconnections can occur in any context – commercial and domestic, urban and rural – they are most associated with densely populated urban areas, and with homes built since the 1950s that have been modified from their original character by extensions, en-suite bathrooms, conversion from houses into flats, and so on. "A lot of people are completely unaware that there are two separate systems for wastewater and surface water, and it probably isn't helped that central London is a single combined system," says Broadbent. "People have the incorrect perception that everything goes into the same drain eventually." www.wwtonline.co.uk | WWT | DECEMBER 2017 | 17 Appliances which have been incorrectly connected to surface drains rather than sewers are a significant cause of pollution. So where does responsibility lie for putting them right, and how are water companies tackling the issue? By James Brockett Kitchen waste in drains can be a sign of a misconnection misconnections, but there is little doubt that it is enough to negatively impact the status of many bodies of water under the Water Framework Directive. Yet because of the diffuse nature of the pollution caused, misconnections can lie undetected for years. So where does the responsibility lie for resolving this problem, and what are water companies doing about it? Andrew Broadbent, Environmental Protection Manager at Thames Water and chair of the National Misconnections Strategy Group, says that many misconnections can be blamed on dodgy DIY from householders.

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