Water & Wastewater Treatment Magazine
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www.wwtonline.co.uk | WWT | DECEMBER 2017 | 19 M ost water companies in England and Wales have AMP6 projects which focus on improvement of environmental water quality in their local catchments – whether for inland watercourses or for bathing water – which include an element of highlighting and tackling misconnections. This type of proactive work typically forms a part of the River Basin Management Plan (RBMP) which water companies work on together with the Environment Agency, local authorities and other environmental stakeholders. In addition, water companies will react to reports of pollution from the public, and where misconnections are identified as a likely cause this can be the spur for further action. In such areas a sustained campaign, with the help of specialist contractors, can uncover hundreds of misconnections and make a marked difference to environmental water quality. "If we identify diffuse, light pollution that comes from multiple sources, it's highly indicative that it's misconnections or private sewer issues," says Thames Water's Andrew Broadbent. "In these circumstances, that could be channelled into a specific programme of work where we appoint specialist contractors to go out and do a methodical strategic approach to investigating the whole catchment. Misconnection discharges can be intermittent, depending on when the household has been using the appliance, so you can't just look at a catchment at a single time on one given day, you've got to assess the catchment repeatedly over a period of time, and then follow it up with a survey of the individual properties down to the appliance level." Water companies typically use a combination of techniques in these investigations: • Visual checks around surface water outfalls are usually the starting point for investigations. Sewage fungus – a mass of filamentous bacteria that grows in response to excessive nutrients in the water – is normally a clear sign of pollution, while the presence of grease and fat is oŠen indicative of kitchen waste. • The installation of temporary traps or screens is oŠen then used to pick up tell-tale debris, such as kitchen scraps, bathroom waste or traces of detergent, that should not be found in a stormwater. • Once at the property level, dye testing, where a harmless coloured dye is put into a sink or appliance to work out where it is connected to in the network, is the most commonly used way of establishing that a misconnection has occurred. • Some utilities and contractors also use CCTV attached to crawler devices to enter the sewer network and follow its route towards the source of pollution. • PREVENTION While water companies, in collaboration with local authorities, can do a lot individually in their regions on tackling misconnections, there is also a sector- led national effort on awareness and educational campaign to prevent misconnections from happening in the first place. The National Misconnections Strategy Group, which has representation from water companies across the UK, runs a campaign called Connectright (info at www.connectright.org.uk) to give the public information about how household drains should be connected. One of the key messages of the campaign is persuading the public to use plumbers that are part of the water industry's accreditation scheme, Watersafe (www.watersafe.org.uk) when making alterations to their pipes and drainage. Using an accredited plumber can reassure the customer that the plumber is conversant with WRAS water regulations and the risk of misconnections. It remains the case that the majority of plumbers do not come with this reassurance: only 5,500 plumbers are Watersafe accredited, out of an estimated 84,000 working in the UK. • FACTFILE • It is estimated that 15% of rivers in England and Wales, and 9% of bathing waters, have failed water quality standards as a result of misconnections • Thames Water has uncovered around 5000 properties with misconnections so far in AMP6. • Although they currently receive less attention, misconnections in which surface water is directed into foul sewers are also problematic: this can overburden sewers with rainwater during storms and contribute to sewers leaking or cracking. • WATER COMPANY RESPONSE Washing machines, along with sinks, are the most commonly misconnected appliances