Maketu Wastewater Treatment Plant – soakage field upgrade

Kia ora, welcome to the Maketū Wastewater Treatment Plant project page. Here, you’ll find everything you need to know about the project, including latest updates, and a timeline of upcoming steps.

About the project

Starting in June 2025, we began upgrading the soakage field at the Maketu Wastewater Treatment Plant to make sure the system continues to work efficiently and protect the surrounding environment - including the nearby estuary.

The 4.2 hectare soakage field sits next to the treatment plant and plays a vital role in the final stage of the treatment process. Once wastewater has been fully treated, it’s piped into the field where it soaks down into the soil. This land-based approach helps filter out any remaining nutrients, with grasses planted over the area to absorb nitrogen. A local farmer cuts and removes the grass to prevent nutrient build-up. This is all part of our resource consent to help protect the estuary and avoid contamination of local waterways.

Click on the below image to open a photo sphere of the

Maketu Wastewater Treatment Plant and surrounding area. Scroll to look around.

What's happening now? (24 June 2026)

Since our last update, we’ve been making improvements to the infrastructure that delivers treated wastewater to the disposal field. This has included upgrades to the controls, valves and main pipeline.

We’ve also completed a new design for the underground pipe network that distributes treated wastewater throughout the disposal field. Work to replace the existing pipes is expected to begin in August 2026.

26 September

We're making good progress on upgrading the soakage field. Recently, we've fixed some leaks, cleaned the main pipeline, replaced a few broken valves and adjusted pumps so water flows correctly. Next, we'll test all pipes to make sure nothing is blocked, check the valves work properly, set up the cleaning system, and flush the pipes with a safe cleaning solution.

For the technically inclined, here's a more detailed breakdown:

Recently completed

• Identified and repaired more field leaks
• Cleaned the main pumped pipeline
• Replaced faulty switching and controlling valves in the field chambers
• Tuned the decant pumps to provide the required pressure and flow out into the field

What's next

• Running the disposal field and testing each dripline to prove there is no blockage
• Testing each submain and dripline flushing valve via telemetry, to prove that this valve is operational
• Commission the chlorine (Cleaning) injection system
• Clean all submains and driplines with chlorine solution

Got questions, or want to kōrero?