Ngā take totoka koiora
Our biosolids challenge
Every time you flush or shower, your wastewater begins an important journey. It travels through a network of pipes to a treatment plant, where it’s carefully cleaned before being returned to nature. During this treatment process, soil-like material called biosolids are produced. By 2035, we’ll need a new way of managing biosolids in Auckland – so planning is getting underway now.
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Why are we talking about this?
All of Tāmaki Makaurau’s wastewater treatment plants produce biosolids. We have a range of options available for their disposal, which include trucking them to certified commercial landfills or turning them into compost for use as a fertiliser. While these have been serving us well, we need to explore other options for managing biosolids in the long term, to ensure we have reliable and resilient servicing solutions in place for our growing city.
At our largest wastewater treatment plant in Māngere, where three quarters of Tāmaki Makaurau’s wastewater is treated, we are using biosolids to rehabilitate an area on Te Motu a Hiaroa (Puketutu Island) that was quarried from the 1950s until the early 2000s.
It's working well but it won’t last forever. By 2035, the rehabilitation project on the island will be complete; and Auckland will need a new proven and reliable solution in place that is capable of handling more than 175,000 tonnes of biosolids each year.
What happens when you flush?
This short video looks at what biosolids are and how we currently manage the 400 tonnes a day produced at our Māngere Wastewater Treatment Plant.
What's the challenge?
Over the next year, we’ll be assessing our options for managing biosolids and we want you to help shape our plan.
Each approach has benefits and trade-offs. That's why your feedback matters – because it will help us to understand what Aucklanders value most as we decide on a solution.
Watch this video to learn more
Come and talk to us
We’ll be at the Māngere Town Centre on Saturday 29 November, 10am – 4pm. If you’d like to know more about biosolids, drop in and say kia ora to one of our experts. More details to come.
What's the timeline?
This shows the key steps from:
- 2025-26: Exploring options: We'll narrow down the broad options to specific areas.
- 2027-28: Refining the path: We'll have decided what the solution is and where it will be.
- 2029-30: Formal steps: Statutory approval and final design.
- 2031-34: Bringing solutions to life: Design and construction begin to deliver the agreed solution.
- 2035: Commissioning: The solution is ready to serve future generations.
You can also email us at [email protected]
FAQs
FAQs
Why are you talking to the community about biosolids?At our largest wastewater treatment plant in Māngere, where three quarters of Tāmaki Makaurau’s wastewater is treated, we are using biosolids to rehabilitate an area on Te Motu a Hiaroa (Puketutu Island) that was quarried from the 1950s until the early 2000s.
It's working well but it won’t last forever. By 2035, the rehabilitation project on the island will be complete; and Auckland will need a new proven and reliable solution in place that is capable of handling more than 175,000 tonnes of biosolids each year.
Over the next year, we’ll be assessing our options for managing biosolids and we want you to help shape our plan.
Each approach has benefits and trade-offs. That's why your feedback matters - because it will help us to understand what Aucklanders' value most as we decide on a solution.
At our largest wastewater treatment plant in Māngere, where three quarters of Tāmaki Makaurau’s wastewater is treated, we are using biosolids to rehabilitate an area on Te Motu a Hiaroa (Puketutu Island) that was quarried from the 1950s until the early 2000s.
It's working well but it won’t last forever. By 2035, the rehabilitation project on the island will be complete; and Auckland will need a new proven and reliable solution in place that is capable of handling more than 175,000 tonnes of biosolids each year.
Over the next year, we’ll be assessing our options for managing biosolids and we want you to help shape our plan.
Each approach has benefits and trade-offs. That's why your feedback matters - because it will help us to understand what Aucklanders' value most as we decide on a solution.
What are you doing to engage Māori and mana whenua?Mana whenua are active partners in this project. They’re contributing through regional wānanga and guiding our approach using mātauranga Māori principles.
Mana whenua are active partners in this project. They’re contributing through regional wānanga and guiding our approach using mātauranga Māori principles.
What is the survey about?We are running a short survey in October and November 2025 to help us understand what Aucklanders value most when it comes to managing biosolids - such as safety, cost, environmental protection, or cultural fit.
We are running a short survey in October and November 2025 to help us understand what Aucklanders value most when it comes to managing biosolids - such as safety, cost, environmental protection, or cultural fit.
How can I stay informed? We will share updates on this page on our website as well as through our social media channels as the project progresses.
We will share updates on this page on our website as well as through our social media channels as the project progresses.
Related content
Our job is to collect your wastewater, treat it to a high standard so it doesn’t pollute the environment, and then dispose of it responsibly.
Our aim is for the people of Auckland to have access to clean and healthy water now and in the future. This means we need to look after our environment and respond to climate change.
Our servicing strategies guide planning for infrastructure investment and address population growth while sustaining healthy communities and environments.