Up to 31 per cent of treated and supplied water is being lost through leaks in Wellington's network. Photo / 123RF
Up to 31 per cent of treated and supplied water is being lost through leaks in Wellington's network. Photo / 123RF
Nearly one third of Wellington City's most critical drinking water pipes are in poor or very poor condition, but there's no concern about a contamination risk.
The issue is the amount of water being lost through leaks - up to 31 per cent of treated and supplied water is lost in Wellington's network.
Wellington Water has completed an urgent assessment of "very high criticality assets" across the capital.
This was a recommendation of the mayoral taskforce into three waters after two major wastewater pipelines unexpectedly failed within a month of one another.
An asset is considered to be very high criticality if its failure has an unacceptable and extensive impact on the livelihoods of people and the environment, and it would take more than one day to restore service.
A condition assessment update published in an upcoming Infrastructure Committee agenda shows nearly a third of these drinking water assets are in poor or very poor condition.
That's the equivalent of about 2.5km worth of pipes.
Wellington Water is investigating these pipes for renewal and has recommended a valve maintenance and replacement programme.
The assessment said pipes in poor condition don't always require urgent replacement or repair, but they are near or at the end of their expected life.
Only those assets in very poor condition where service failure has occurred, like a collapsed pipe, require urgent intervention.
Wellington Water network engineer Aidan Crimp said high criticality assets made up about 7 per cent of Wellington Water's asset base.
Overall, there are 922km of drinking water pipes in Wellington City.
"This programme is important as it assesses the condition of the region's infrastructure as part of our ongoing work to improve the water system.
"We can then lay out short- and long-term renewals programmes that will minimise outages and reduce the cost of unplanned repairs."
Infrastructure Committee chairman councillor Sean Rush. Photo / Mark Mitchell
Only 10 per cent of very high criticality wastewater assets were in poor or very poor condition, 10km, and just 2 per cent of stormwater assets, 1.6km.
Infrastructure Committee chairman councillor Sean Rush said Wellington's drinking water remained clean and was not at all in danger.
"The problem here is water losses and a mix of renewals and metering will address that."
The Wellington City Council is yet to make a decision on installing residential water metering.
Rush said Wellington Water was undertaking the largest asset condition assessment programme ever completed in New Zealand.
This is supported by ratepayers who have told councillors they want more investment in three waters, Rush said.
"We need to update ourselves regularly on the asset condition if we are to complete renewals in a planned manner, rather than as a response to an unexpected event."
The committee's deputy chairwoman, councillor Jenny Condie, said the focus publicly has been more on wastewater failures because those have been the high-profile ones.
"But within the council, and certainly within the mayoral taskforce on three waters, we're very aware of the fact that there are also likely to be failures in our drinking water pipes.
"We know we have high water loss in this region. The reality with drinking water pipes is that when they break we don't always notice it."
