Water & Wastewater Treatment Magazine
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14 | APRIL 2019 | WWT | www.wwtonline.co.uk The Works: Pipes and water quality with the regulator to understand what criteria could be used to con rm when phosphate dosing can be switched o , and a project is to be carried out in the coming year which aims to clarify these issues." The cost of pipe replacement ought not to be considered a barrier, since the whole-life-cost saving from stopping phosphate dosing for any particular geographical area outweighs the cost of replacing communication and supply pipes, adds Philp. GIS mapping Water companies south of the border have the same challenges. Severn Trent will be installing boundary boxes and meters at all properties in its area over the next three AMP periods as part of its water re- sources management plan, and it intends to take the opportunity to record and map exactly which buildings are served by lead pipes. The approach will eventually give the utility a comprehensive picture of the remaining lead that is present, but the company's 2020-25 business plan makes it clear that this will take many years. "In 25 years' time we will know where all lead pipes are, both ours and those that are privately owned," reads the plan. "To get there, we will need to improve asset data records on communication and supply pipe material and location. We have started to do this and have created GIS based risk mapping which uses data gathered when we have replaced/ separated common supply pipes, also using housing age, postcodes and water quality failures. This provides broad areas where lead is most likely to be so we can target investment and communications." Awareness and ownership But with supply pipes and plumbing being the householder's responsibility, customer awareness and willingness to pay for replacement is a major barrier to creating a lead-free network. In a survey of 2,000 people by WRAS WaterSafe in 2018, 68% were unable to say whether they had lead pipes in their home, and only 7% said they would check whether a home was supplied by lead pipes when moving into a new property. "Our customer research shows that there is a generally low awareness of lead, with most customers assuming lead pipes were eradicated some time ago," adds Scottish Water's Rachel Philp. "Younger people do not recall the move from leaded to unleaded petrol and, as a result, are less aware of lead issues." Most water companies have a policy of replacing lead communication pipes if requested by a householder who is having their part of the pipework replaced, but only a relatively small number of " LEAD WATER QUALITY FAILURES BY COMPANY2007 Water company Number of failures Affi nity Water 4 Anglian Water 4 Bristol 1 Dwr Cymru 1 Essex & Suff olk 2 Northumbrian 5 Portsmouth 2 Scottish Water 14 South East Water 4 SES Water 0 Severn Trent 12 Southern Water 2 South Staff s Water 0 South West Water 3 Thames Water 20 United Utilities 5 Wessex Water 1 Yorkshire Water 4 (Source: DWI/DWQR) and minimises water quality failures, companies will require a comprehensive knowledge at a property level before they can have the con dence to turn o the orthophosphate dose – a knowledge that is currently lacking. For example, Scottish Water uses dosing at 85 of its 233 water treatment works – although this dosing covers most highly populated urban areas, to the extent that 95% of the Scottish population receives water that has been dosed with orthophosphate. The utility has made good progress over the years in replacing communication pipes that are its responsibility – it estimates that there are only 72,000 lead communication pipes le™ among its 1.8 million connections – yet uncertainty over customer-side lead pipes needs to be resolved before dosing can be switched o . "Because supply pipes are the responsibility of the customer and the quantity of lead supply pipes and plumbing are not recorded, there is concern about switching o phosphate before knowing whether or not customers have removed their lead pipework," says Rachel Philp, Water Service Strategy Team Leader with Scottish Water. "The position has been that our regulator, DWQR, will only allow us to stop phosphate dosing if all lead supply pipes have been replaced. We are working Lead pipes: who has responsibility?