Water report exposes leaks, overflows and consent breaches

New Zealand’s water infrastructure is under strain. A new national report reveals widespread leakage, wastewater overflows and ongoing non-compliance across council networks.

The Water Services Authority – Taumata Arowai’s Network Environmental Performance Report 2024/25 paints the first complete national picture of public drinking water and wastewater network performance, and the findings are stark. The report says many networks are under “severe” pressure, with better data, maintenance and targeted investment urgently needed to reduce risks to public health, the environment and long-term system resilience.

Among the most concerning findings is the scale of wastewater overflows. Councils reported 11,535 overflows in the past year, averaging about 31 a day, with causes including capacity constraints, wet weather, blockages, infiltration and poor asset condition. The report also notes that blockages remain a major preventable cause, often linked to fats, oils, wet wipes and other unsuitable items entering the system.

South Island councils feature prominently in the report’s problem list. Grey District Council recorded the highest annual water loss of any council, at more than 1300 litres per connection per day, followed by Queenstown Lakes District Council at 675 litres, Ashburton District Council at 597 litres and Clutha District Council at 441 litres. Christchurch City Council was significantly lower at 240 litres per connection per day.

Wastewater performance was also especially poor in parts of the South Island. Buller District Council reported 1041 wastewater overflows per 100km of pipe, while Waitaki District Council recorded 91 overflows per 100km. By contrast, Christchurch City Council recorded just two overflows per 100km.

The report highlights another major concern: compliance. Around 22% of wastewater treatment plants nationally are operating on expired resource consents, some for more than 20 years, and close to half will need re-consenting within the next decade. Taumata Arowai says non-compliance with wastewater consent conditions is widespread across the three-year period covered by the report.

For councils, the message is clear: maintenance backlogs, ageing assets and climate-driven pressure are no longer abstract risks. They are already showing up in leaking pipes, overflowing wastewater systems and breaches of consent conditions — with communities, waterways and public health all exposed to the consequences.