Plug leaks, not reservoirs

Ofwat would prefer water companies to reduce leakage before building new reservoirs. But what is an acceptable level of leakage?

A number of listening devices can be used to locate damaged water mains

A number of listening devices can be used to locate damaged water mains

Thames Water did have plans for a new reservoir to supply London from Abingdon. But the government demanded leak reduction instead of reservoirs, so Thames has had to find new ways of repairing mains without traffic disruption. Thames has, until recently, been losing around 30% of its water supplies through leaky pipes.

Now Ofwat figures show Thames, with 32,000 km of water mains, has made one of the largest reductions (14%) of all water companies over the past year. Over the last three years, the company has cut leakage by 38%. Tackling leakage is particularly difficult in London. The London clay in which its pipes are buried expands and contracts a great deal when temperatures change, and traffic congestion can make it difficult to find leaks and fix them. Much of Thames' leak detection work is therefore done at night. Another problem is that London has so many tall buildings, meaning water has to be at a high pressure to reach the upper floors. In addition to standard leak detection equipment, Thames is using 'leakage bollards'. These metering devices now exist throughout the Thames network and relay information back to the company's control centres.

Thames is also trying to promote the efficient use of water by its customers, through the provision of information and water saving devices. A free leakline has been introduced for customers to report leaks and a free repair service for customer pipes.

Yorkshire Water has a very different situation and is having to deal with a vast and ageing network in hilly terrain. Leakage has now been cut by 40%, enough to supply a city the size of Leeds. For the 1999/2000 period, Yorkshire Water's target was to reduce leakage to 338Ml/d across the whole region but this has now been reduced to 317Ml/d. Most water companies have developed their own approach to leak detection. Yorkshire is working with the government's Defence Evaluation and Research Agency (DERA), to see if technology developed for the Navy to track submarines can also be used to detect leaks.

North West Water claims to have achieved the greatest reduction of all, reducing leakage by 48% since 1992-93. North West has about 40,000km of water mains with about 27M joints, any of which could be leaking. For instance, Manchester, Salford and Trafford have nearly 3,000km of water mains with more than 2.5M joints.

Years of subsidence, road vibration, corrosion, frosts and dry spells have weakened many of the old cast iron mains, many of which are more than 100 years old.

More than 5,800km of water mains have been refurbished or replaced across the North West region since 1989. Pressure control is also being used to reduce leakage. The majority of leaks are never visible on the surface, so tracking them down is a difficult and skilled job. North West is working with a number of research companies to develop new techniques, such as 'aqua-logging' technology. A highly sensitive microphone is attached to the water main to listen for telltale sounds given off by leaks. The information is then downloaded to a computer and analysed.

The company is also working with a research company to develop a radar system that senses where a pipe is vibrating due to a leak. Trials have also been carried out with a new electronic listening device in Greater Manchester. A larger trial is due for completion in December.

There must be a limit
Of course there is a limit to how far leakage can be reduced. Anglian Water has been among the most outspoken in this regard. Once a 'floor' of minimum losses is reached, investing in new resources becomes a cheaper option than spending further millions on cutting leaks.

Anglian believes 11% leakage is about right, and that below this remediation is simply too costly. Beyond this, water companies may well have to look at a fundamental industry restructuring.

Increased competition should in theory encourage leak reduction, and Ian Byatt was always keen to try and create competition in what he saw as a complacent industry. He favoured direct competition between water companies, in which one would develop resources in another's company's established territory, using the latter's pipes to reach a new market under the "common carriage" principle.

Philip Fletcher, the new Ofwat boss, has indicated that he will consider other options, for instance separating the ownership of assets from their operation. Speaking in September for the first time in his new role as water regulator, Fletcher said that allowing water companies to put the operation of their networks out to tender could be the best way of creating competition.

Although competition is by no means well-established, leak reduction is already well underway. This is despite a considerable disincentive to carry out repairs in the rules drawn up after privatisation.If water companies invest in new reservoirs or other large schemes, they are allowed to increase water bills but no such provision exists for leakage repairs. This anomaly was not lost on deputy prime minister John Prescott on taking over the DETR. Prescott ordered a water summit in 1997 and demanded action on leaks before the construction of any new reservoirs, and the water companies were duly set targets for leak reduction.

Last year Prescott announced the results of his crackdown on leaks and, for the first time since 1993, said hose pipe bans would be unlikely in England and Wales. Following the summit, Prescott said levels of leakage had fallen consistently. All but South East Water and Dee Valley Water managed to meet Ofwat's targets for 1999-2000.

According to Ofwat, water companies' leakage levels have fallen by almost 35% since 1994. By March 2002, Ofwat says leakage in England and Wales could fall by a another 9%. This would see leakage in England and Wales down to just over 3,000Ml/d, a reduction of more than 2,000Ml/d from the 1994/5 level - enough to serve more than 13M people.

A lesson learnt?
To Yorkshire Water, it was the only solution but to the public it was an unbelievable fiasco. A dry summer in 1995 left Yorkshire with no option but to deliver water supplies to Leeds from Cleveland by road. Over 200 tankers worked around the clock to carry raw water over 100km.

Around 5-6Mg/d of water were carried from Long Newton reservoir near Darlington to Yorkshire's Eccup WTW near Leeds. It was a ridiculous situation, but it helped to focus attention on leakage. It is a story with a happy ending or, at least one with a happy ending in sight.



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