Modelling Intermittent Water Supplies to Improve Public Health

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Modelling Intermittent Water Supplies to Improve Public Health

In Toronto, when you turn on a water tap, water comes out. But for more than a billion people around the world, that is not always the case.

“About 21% of the world’s water pipes don’t usually have water in them,” says Professor David Taylor (CivMin, CGEN), who studies water treatment and distribution in the developing world.

“For example, in many neighbourhoods in Delhi, where I’ve worked extensively, the city will deliver you two hours of water in the morning, and then another hour in the evening,” he says.

North American water industry experts may consider this form of intermittent water delivery bizarre: pipes that are constantly emptying and filling are more prone to wear. Keeping pipes full also creates positive pressure that keeps contaminants out — when they are empty, sewage or other contaminants can leak in, only to get washed downstream the next time the pipes fill.

But Taylor’s research shows out that turning off the taps at the source can actually have some advantages.

“If you have no budget to repair leaking pipes, the simplest solution is to turn the water off, because an empty pipe can’t leak,” says Taylor, who recently became the first budgetary appointment to the Faculty’s Centre for Global Engineering (CGEN). “If Delhi’s pipes were full all the time, they would leak seven times as much water as they do now.”

During his PhD research at the Massachusetts Institute of Technology (MIT), which was supported by The Tata Trusts, Taylor focused on modelling the distribution system in Delhi and trying to determine how much water per day would meet the needs of the city’s 18 million residents. One of the key challenges was a lack of basic information about the system’s structure.

“Missing information is a classic problem for old infrastructure; in London, England, many of the storm sewers are still unmapped,” says Taylor. “The same is true for Delhi’s water pipes. I had operators tell me ‘We know we’re missing at least one 12-inch diameter pipe that joins network one and network two. How do we find it?’”

Without the resources to deal with missing or broken infrastructure, utility operators typically use trial and error to make the best use of the system that they have. That’s where Taylor sees his modelling and analysis work providing the most value.

“It’s partly a triage problem,” he says. “Maybe 24 hours a day really is ideal, but it could also be the case that four to six hours a day is exponentially better than one or two. So maybe we should get all areas to that level as a first step. And if that’s the goal, where do we start? Those are the questions I work on – which we need to answer if we’re serious about meeting the UN’s Sustainable Development Goal 6.1 and the Human Right to Water.”

Reference: 

David D. J. Taylor, Alexander H. Slocum, Andrew J. Whittle, "Analytical scaling relations to evaluate leakage and intrusion in intermittent water supply systems", Los One, May 2018, DOI: 10.1371/journal.pone.0196887

Source: University of Toronto

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