(Inside Science) -- Across the United States, underground labyrinths of leaky pipes lose more than a trillion gallons of water a year -- and the problem is mirrored around the world.
"It’s a huge problem, especially in the cities," said Daniel Tartakovsky, a professor of energy resources engineering at Stanford University in California. Tartakovsky and his former student Abdulrahman Alawadhi from the University of California, San Diego have proposed a way to improve a traditional method of detecting these leaks.
Water companies know the supply pipes -- some of which are more than a century old -- lose water because a significant portion of what the companies put into the distribution system never reaches customers. In North America, it’s estimated that between 20% to 50% of the water escapes from water utilities’ pipes before it’s delivered to homes or businesses. In areas of the country already experiencing water shortages, the leaks exacerbate the problem. Burst pipes can also flood buildings and destroy roadways.
One tool that water companies use to locate leaks is called a water hammer test. They suddenly close a valve, forcing the water to change direction. The resulting shock wave, which the companies can measure using existing pressure sensors, holds clues to the location and size of any leaks.
Tartakovsky and Alawadhi developed a new way to interpret the data from these water hammer tests. Their method narrows the range of possible leak locations without requiring lots of additional computing resources. That is important, Tartakovsky noted, because especially in cities, water companies don’t want to tear apart any more infrastructure than necessary to find a leak. It should be easy for companies to try out the new method with their existing resources, Tartakovsky said, and the team has already been approached by water companies from Great Britain and Italy that want to learn more. The researchers published an analysis of the method applied to leak detection in transmission mains in February in the journal Water Resources Research, and they submitted another paper that applies the technique to water distribution networks.
While it might be better to replace all aging water infrastructure, rather than continually patch it, the costs and disruption are daunting. The U.S. Environmental Protection Agency’s latest drinking water infrastructure assessment, released in March 2018, estimated that more than $300 billion was needed to replace or refurbish the country’s deteriorating pipelines. Since then, hundreds of thousands of water mains have sprung new leaks.