Wellington councils have agreed to further investigate the viability of using water meters across households.
A new report, commissioned by Wellington Water and completed by Ernst Young, showed in a worst-case scenario, the region will be running out of water as soon as 2026.
Demand as well as the population was growing, and there was not enough being done to mitigate it, the report found.
One option to provide such resilience to mitigate the risk was to find a new water source, but the report warned "the financial cost and environmental impact of a new water source is likely to be significant. Initial estimates place the finacial cost of construction at $250m".
There are two storage lakes in use, and appetite to construct a costly third is non-existent.
An alternative solution is to reduce demand on water supplies. Network performance modelling by Wellington Water showed a 10 percent reduction in demand would mean the need for a new water source could be delayed by 12 years.
A way to reduce overall demand is to install water meters across the region.
"The installation of advanced meter infrastructure (AMI, or "smart" meters) in every household with automated reporting has been identified as a proven methodology to find leaks and provide customers timely advice on water usage," said David Bassett, chair of the Wellington Water Committee.
"The committee will be working closely with shareholder councils before any final decision is made and this will involve consultation with all communities."
What is the pressure on the capital?
Out of the five largest cities, Wellington's water daily residential consumption is second highest, at 227 litres a day per resident.
Many of Wellington Water's resources are under strain, and all the supply catchments are fully allocated in terms of core allocations.
The region is expected to grow in population, and the demand for water is soon expected to outstrip supply.
Wellington Water is also facing pressure managing its network - the organisation has low confidence in the condition of its pipes. More than 46 percent of the network has been described as "fragile."
The organisation has accepted it does not have the capacity to deal with a one-in-50-year drought.
What are the solutions being offered?
Three options are being considered which would bring in residential metering:
- Universal metering with analogue customer meters and Manual Meter Reading (MMR) with feedback given to customers on quarterly consumption
- Universal metering with Automatic Meter Rading (AMR) customer meters with feedback given to customers on monthly consumption
- Universal metering with Advanced Metering Infrastructure (AMI) and a self-service customer portal (app) for each customer showing daily consumption and comparison against others plus leak alerts pushed to customer
The first option has already been implemented in the Kāpiti Coast, and has equated to a 26 percent drop in peak consumption.
None of the options come cheap. The first would cost more than $60 million, the second more than $120m and the third nearly $145m.
The last option was the only one which was assessed to bring value for money, with $138m of the costs offset by deferred capital expenditure, deferred operational expenditure, and long-term savings of reduced electricity and chemicals cost.
That is still significantly less than the cost of constructing a new storage lake.
Only Upper Hutt Mayor Wayne Guppy opposed, saying the real issue was with lack of storage supplies across the region.
"That's the urgent thing, making sure we increase bulk storage in the Wellington region. Otherwise, in 10 years time, we'll be sitting round here like they did in Auckland last year, saying we're short of water.
"Don't get distracted by the other thing, the priority should be the bulk storage to Wellington."
Porirua mayor Anita Baker suggested work to get people to reduce their water consumption should start now.
"In the short term, we need to actually do a push out to our residents about how to save water. In Auckland, they don't brush their teeth with the tap running, in Wellington they do. Have a bucket in the shower to save your water for the garden.
"There's so much we're not telling our residents, and there's so much they don't actually understand."
Wellington Water will now complete a business case into the cost and rollout of water meters for approval by councils.