1 July, 2025

Watercare installs sensors to get the jump on wastewater spills

Flood sensitive… Installed beneath manhole covers, new equipment will provide more data on water levels

Sensors will be installed across Watercare’s wastewater network, including the flood-prone Wairau catchment, to better monitor overflows in real time.
The rollout of 5000 sensors beneath manhole covers began this month and is expected to take a year. They will record wastewater levels every 15 minutes and provide daily data reports to a monitoring system, allowing proactive management and intervention.
When a spill is detected, sampling frequency will be automatically increased. The sensors will also identify pipe blockages and can detect any stormwater or groundwater intrusion. In time, they will be linked into Safeswim, helping improve communications about water safety.
Watercare was unable to tell the Observer how many sensors were planned for Wairau or when they would be installed.
Smart systems manager Dave Moore said they were part of a $12 million investment to gain insights into the performance of the network of almost 9000km of pipes.
Watercare was also investing in a wastewater analytics package that would analyse the data from the sensors and other sources, employing artificial intelligence tools.
The Devonport-Takapuna Local Board is eager to know when the sensors are coming locally, given Wairau was particularly hard-hit during the floods of early 2023.
But council department Healthy Waters, like Watercare, was last week unable to provide a local timeline.
Healthy Waters, which manages stormwater, is also investing in more technology.
During storms at Easter, it used a flood intelligence camera in Milford to monitor fast-rising water. The camera surveyed upstream from East Coast Rd to a trash grille in the lower Wairau Creek which was quickly swamped overnight on 19 April. This helped identify a blockage in the grille that was removed the following day. Three more cameras are in the wider Waiaru area.
“It’s a really powerful tool that should give reassurance to the public we are monitoring issues,” said Healthy Waters principal for strategic programmes, Elizabeth Johnson.
The Easter downpour was as intense for two hours as that which caused the Auckland Anniversary Day floods of 27 January, 2023, she said. Luckily the rain stopped more quickly.
The trash rack is checked and cleared before and after storms.
Healthy Waters gave other examples of work it was doing locally to mitigate flood risk, including more catchpit checks and flushing. Water channels were inspected every three months and the 2500 catchpits in Wairau checked at least twice yearly, it said.
Since the 2023 floods, upgrades had also been done on Kitchener Rd, East Coast Rd and Shakespeare Rd in Milford; on Altona Rd in Forrest Hill; and Arrow Rd in Castor Bay.
Board members welcomed the monitoring and maintenance work, but were frustrated at the slow progress towards any substantial infrastructure improvements locally
Healthy Waters said these would only come after Stage 1 work on the proposed AF Thomas Park-Takapuna Golf Course water detention scheme.
“The benefits of Stage 2 can only be realised when we can detain this water,” said Tom Mansell, head of strategic partnerships for flood resilience. With physical work not forecast to start on Stage 1 until 2027 and take several years, Milford will have to wait for the focus of works to shift there.

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