In the pipeline

Oct 27th 2009
From Economist.com

A new system could save water by sealing small but pervasive leaks

WATER is precious, yet much is wasted. The World Bank estimates that 88 billion litres of treated water is lost from leaking urban pipelines every day, a quantity split evenly between rich and poor countries. Now an Israeli company called Curapipe has developed a system that aims to seal leaks cheaply with only a small disruption to the water supply.

Much of the wasted water is lost through what the International Water Association, an industry body, calls “background leakage”—that is, small but widespread cracks that drip water continuously. Indeed, background leakage is so pervasive that water suppliers accept 3,500 litres of water per kilometre of pipe per day as the minimum achievable loss. Short of replacing the entire water main, which is both expensive and disruptive, the only way to cut background leakage below these levels has been to reduce the water pressure.

Curapipe’s system piggybacks, as it were, on the system of “pigs” commonly used to clean urban water mains. This cleaning regime works by suspending the supply for a couple of hours while a bullet-shaped, spongy object allegedly resembling a pig is inserted into the pipe and then forced through it using water pressure, taking mineral scale and sediment with it.

The device developed by Curapipe consists of a train of two pigs with a viscous composite trapped between them. This composite acts as the sealant. The train is forced through the system in the usual way. When it reaches a crack, the sealant is sucked out of the train and into the crack in the same way that water is lost. The composite fills the crack and then hardens in situ. Once the pipe has been flushed, the water supply can be restored.

And not only water. Oil and gas pipelines are more closely monitored and more thoroughly maintained than water mains, yet Peter Paz, Curapipe’s boss, thinks the firm’s system could also be used to prevent small but devastating leaks in such pipelines. Big leaks in oil and gas pipelines are tackled immediately, but “pinhole” leaks can go undetected and result in a larger spill than a rupture would produce. In August, for example, some 4m litres of oil were spilt at the Coussouls de Crau nature reserve close to the Camargue, in the south of France. Although the pipeline was monitored, the leak went undetected until a park warden discovered it. If the system developed by Curapipe had been used, Mr Paz reckons it would have prevented the spill, thereby saving wetlands as well as water.

Comment

"88 billion litres of treated water is lost from leaking urban pipelines every day". This is water that we need to drink.