Waging war on leaks won’t win Mother City’s water battle

Minister of Water Affairs and Sanitation Nomvula Mokonyane met Cape Town mayor Patricia de Lille and other officials early last month and urged the city to fix leaks as a way to further prevent unnecessary losses.

But experts say, at this stage, it’s no silver bullet to solve the city’s problems.

Kobus van Zyl, a hydraulic engineer in the University of Cape Town’s department of civil engineering, said, in fact, the city has the best water infrastructure in the country when it comes to leaks.

“You can’t get leakage to be zero in any system. There will always be some and you won’t find them all, because some will be hidden from view underground.”

The infrastructure leakage index rates how leaky a system is. Cape Town, at 2.2, is the best in the country, said Van Zyl. Johannesburg is at about eight.

“If the city spent all the money in the world on leakage reduction, they could get it down to maybe 8% instead of 16%. That is part of the solution, to continue to reduce leakage. But if you can spend the same money and get people to use water more efficiently, that is a bet- ter solution,” he said.

“For the same money, you could replace all shower heads with waterefficient shower heads. As a water manager, there are various things you can do. It is about how to spend the available money in the best way to get where you want to be.”

In a water crisis, you reduce consumption and look for short-term gains in supply, which is what the city is trying to do, he said.

Reducing pressure in the pipes reduces stress and helps to contain leakage. But intermittent supply, dubbed water shedding, as a general rule is very bad for the water system. When water is shut off, pollutants can enter externally into cracked pipes. The air in the system also increases the incidence of burst pipes by 300%, Van Zyl said.

“Cape Town has been pretty good in resisting instituting intermittent supply. What they are doing now is probably the right thing to do. This is really an emergency short-term measure … It’s not a good thing, but not as bad as the alternative.”

Ultimately, Cape Town faces a large technical failure brought on by a failure to plan for the worst, he said.

Van Zyl said planning water infrastructure to meet projected water demand is critical and the custodian of that, the department of water affairs and sanitation, should be the driver of long-term planning and thinking about water resources.

The department has said it will fast-track the implementation of the Berg River-Voëlvlei augmentation scheme, which it hopes to complete by the winter of 2019. There are also plans to start work on the raising of the Clanwilliam Dam wall.

The minister has described the water shortage as “the new normal”. —