Media release: Plugging the gap: Aotearoa’s piped water loss far worse than global leaders

Aotearoa New Zealand’s water infrastructure system is leaking at a rate far higher than global leaders, posing risks to public health and wasting around $122 million each year according to the latest Briefing from the Public Health Communication Centre.

Research by Prof Nick Wilson and co-authors from the University of Otago shows NZ’s leakage levels at 22% are far worse than leading European countries such as the Netherlands at 5% and Germany at 6%.

“We also compared countries using the more sophisticated Infrastructure Leakage Index (ILI). NZ ranks near the bottom of 15 OECD jurisdictions in this index, with a median ILI of 2.7 compared to Denmark’s 0.7,” says Prof Wilson.

The authors say it is encouraging that there has been recent progress in managing leaks in places such as beleaguered Wellington and also that nearly three-quarters of New Zealanders surveyed support water metering. Such metering is valuable for detecting leaks and reducing water waste. 

The Briefing calls for more decisive action from policymakers, urging central and local government representatives to commit to sustainable infrastructure investments.

“We must act to address leaking water systems that impact public health, strain local resources, and cost our communities millions of dollars every year. It’s essential for central government to do more to support local infrastructure investments for a resilient and secure future,” says Prof Wilson.

“More generally the broken local government funding model needs fixing. There are many ways to address this – just one being local government keeping GST on rates.” 

The Briefing also includes a historical comparison by estimating leakage rates from four ancient Roman aqueducts. While the calculated estimates ranged from as low as 11% loss for one aqueduct up to 68% for another, these were thought to be likely overestimates. This was because aqueducts typically also supplied water to towns on route to Rome but data on this could not be included in the analysis. Nevertheless, a notable feature of Roman aqueducts was their resilience with one of them, the Valens Aqueduct in Constantinople, functioning for over 1,300 years with ongoing repairs. Another aspect of the resilience of Roman aqueducts, in contrast to modern systems, was that they were entirely gravity-powered.