August 2021

Listening for leaks leads to nine million litres a day in water savings

They’re out in force in neighbourhoods across Tāmaki Makaurau. You may have seen them sporting hi-viz and carrying acoustic listening sticks that have more power than you might first assume.

Known as our proactive leak detection team, they certainly live up to their name. They’re listening for and detecting leaks before they’re even a drop on the surface. With the help of what could be referred to as modern-day magic wands, they’re saving nine million litres of water a day.

“There’s an art to acoustic leak detection," says water engineer and leak detecting expert Lucas Gan. "We listen for signs of a leak by tapping a stick microphone on a meter or pipe connection. Each leak has a different sound. A big leak will sound different to a trickle. The volume of the leak is determined by the sound detected."

When it comes to water savings, if you’re wondering how much nine million litres of water a day is, well, it could supply more than 50,000 people and is more than we produce at our treatment plant in Pukekohe.

Since the team started pacing the streets of Auckland in early 2020, they've swept almost six thousand kilometres of pipes, found 4,500 leaks, and as you can imagine, clocked up a fair few steps.

“Each leak detector walks roughly 5km a day. This includes retracing their steps to double check all the leaks they initially discovered on their first walk through,” says Lucas.

While Auckland has a lower leakage rate across the public network than the rest of the country, Lucas and the team have a solid goal to reduce it even further.

“We’ve increased our leak detection team from 11 to 17 people. Our goal is not only to find more leaks, but to fix them faster and reduce the total amount of water lost.”

There are many causes of leaks from ground movement in extreme weather, wear and tear in older pipes, and vibration damage from heavy traffic. Improvement programme manager Anin Nama says, “Parts of central Auckland seem to have more leaks, which could be because the pipes are older, but also because of the roading developments – in some places, pipes that were originally laid under footpaths are now under roads and therefore are more impacted by traffic movements".

To make inroads and stem the flow of hidden leaks, Lucas and the team have been focusing on areas with high numbers of reported leaks. In January 2020, the Maungakiekie zone, which includes Mt Wellington and Ellerslie, had 248 reported leaks. Fast-forward 12 months and the number had dropped to 67.

“When we find these invisible leaks in our network, we repair them and prevent the associated water loss. But also, by repairing these smaller leaks which are normally invisible on the surface, we prevent larger leaks that can occur when the ground dries up and retracts, causing pipe movement and sometimes breakages,” says Anin.

Once Auckland is back in business and out of lockdown, Lucas and the team will once again be out in force listening for leaks, but this time across Hillsborough, Mangere and Hobsonville.