News and views

Private sewer adoption stores up problems unless water companies get a clear map of the network

21 July 2011

Recent media coverage has indicated that the forthcoming transfer to water companies of private sewers and lateral drains could affect up to 200,000 kilometres of pipework. That spells trouble for the industry unless sufficiently detailed surveys are undertaken, says Mike Page, Quality Manager at Subscan Technology, the UK’s leading specialists in underground surveying.

When the draft regulation for the transfer was published in August 2010, the Minister, James Paice, said, “Transfer will … provide much greater efficiency of effort, environmental stewardship and expenditure at a time when climate change impacts and housing growth may impose greater demands on urban sewerage systems.”

Yet, while water companies, as the statutory sewerage undertakers, maintain publicly available records of their sewerage network, the majority seem to have no desire to upgrade these to include the private sewers they will soon inherit. Indeed, Water UK has admitted that the network is largely unmapped.

It is therefore troubling that the majority of water companies seem content to leave the survey until there is a problem. The repair contractor will be heading to a situation where he has no idea where the private sewers run, what size they might be and to which homes they are connected. Demand for repairs is likely to be high: many householders put off repairs because they know they will have to foot the bill themselves. As soon as they are aware the task is no longer their responsibility, they will be straight on the phone demanding something is done.

While it may seem to make economic sense to map the drains only when a repair is needed, this will inevitably take years to complete and will not provide a comprehensive record of the layout and condition of these sewers. Consumers need clarity and confidence in the service they receive from the water companies; this type of record will enable water companies to estimate the true impact of repairs on customers’ water bills.

A thorough survey will also help the industry identify cross connections of foul water from washing machines and dishwashers illegally connected to the surface water system. This problem constantly shows itself in the pollution of water courses and costs water companies a great deal of money. A good survey of private drains will quickly identify the offenders so action can be taken.

Professional mapping of the private sewer network represents good value for money for water companies and their customers. The record such surveys provide will reduce unnecessary works, enable preventative measures to be taken before priority sewers fail at greater cost and enable companies to identify and quantify their risk and potential expenditure with much greater accuracy.