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HG - Engineering Tomorrow

Kerepehi Water Treatment Plant Upgrade

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Hauraki District Council


Our award-winning upgrade of the existing and failing Kerepehi Water Treatment Plant, increased capacity by 30% and provided local dairy farmers with a reliable water supply - even during the worst drought in 70 years.


  • Optioneering
  • Feasibility studies
  • Preliminary and detailed design
  • Tendering
  • Construction contract administration and construction observation
  • Construction coordination and commissioning

Project Completion


Total project value

$10.2 million

The Kerepehi Water Treatment Plant supplies the Hauraki Plains area and the local dairy farming industry. Hauraki District Council commissioned us to upgrade the 70-year-old Kerepehi Plant to raise the plant’s capacity, meet drinking water standards, and provide farmers with a facility they could rely on for their water needs.

An award-winning $10 million upgrade helped to maintain the region’s economic production during the worst drought on record. Before the upgrade, the plant struggled to produce enough water during high demand periods, and sometimes failed to meet the revised New Zealand Drinking Water Standards.

Our work

We led the project from initial concept design and process selection, through to technology procurement, design, tendering, construction observation and commissioning. After considering numerous options, the design team chose to replace the plant’s aging sand filters with membrane filters and to convert the existing clarifiers into tube settlers. This delivered far greater reliability of supply and ensured that plant capacity would meet demand.

A key challenge was shutting down several of the existing core treatment processes for rebuilding, which involved the risk of compromising supply to the region.


The plant was completed on time and for $3 million less than the initial budget estimate. Most importantly, the plant has increased capacity by 30% providing an additional 3.5 million litres of treated water per day and operating during all conditions. The water always meets the Drinking Water Standards of New Zealand (DWSNZ).


Silver Excellence Award, ACENZ Innovate Awards, 2014

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