Every day, wastewater flows from homes, businesses and industries into a network designed to collect, treat and return it safely to the environment. At IAWAI, our role is to make sure this happens in a way that protects public health, supports growing communities, and safeguards our precious taonga, the awa.
Returning water well
Wastewater carries the traces of everyday life, from kitchens, bathrooms, workplaces and factories. Before it can be returned to the environment, it must be carefully treated.
Our responsibility is to manage this entire journey: collecting wastewater, treating it to a high standard, and returning it in a way that protects waterways. When this system works well, it’s largely invisible, but its impact on health and the environment is profound.
After the flush
IAWAI’s wastewater network is extensive and plays a critical role in daily life across the region. It includes:
- 10 wastewater treatment plants, including Pukete (Hamilton), Ngaaruawaahia, Huntly, Te Kauwhata, Raglan, Meremere, Maramarua, Matangi, Tauwhare and Te Kowhai
- 205 wastewater pump stations
- 1,192 kilometres of reticulated wastewater pipelines
Wastewater from more than 91,000 connections across the region is treated before being discharged, primarily into the Waikato River.
Protecting people, communities and awa
Our goal is to protect the health of communities and the quality of waterways by ensuring wastewater is treated safely, consistently and sustainably. This includes:
- meeting current and future compliance requirements
- renewing ageing infrastructure
- delivering new capacity where growth demands it
- responding quickly when issues arise to minimise impacts on people and the environment
This work directly supports the vision of Te Ture Whaimana o te Awa o Waikato, ensuring decisions about wastewater contribute to the long-term health and wellbeing of the river.
Thinking downstream
As the region grows, wastewater volumes increase alongside population and development. Existing systems, many built decades ago, are under increasing pressure.
Our role is to plan ahead — addressing constraints, upgrading treatment, and building new infrastructure so growth doesn’t come at the cost of river health or service reliability.
Over the next decade, IAWAI will invest in major wastewater projects to improve capacity, resilience and environmental outcomes.
Upgrading and re-consenting treatment plants
We’re progressing staged upgrades and re-consenting at key facilities to meet future demand and compliance requirements, including:
- Pukete Wastewater Treatment Plant (2026-2036)
- Huntly Wastewater Treatment Plant (2026-2036)
- Ngaaruawaahia Wastewater Treatment Plant (2026-2036)
All three discharge into the Waikato River, which is why they're prioritised
New infrastructure for resilience
Planning is underway for a new Southern Hamilton Wastewater Treatment Plant, designed to increase treatment capacity and resilience across the network. We’re also installing wastewater storage tanks to help manage wet-weather events and reduce the risk of overflows.
Supporting growth where it’s needed
Targeted investment is currently focused on increasing wastewater servicing capacity for high-growth areas such as Pookeno, Tuakau and Te Kowhai, where constraints currently limit development.
Looking after what’s already there
Alongside major projects, we continue a district-wide renewals programme, replacing and upgrading ageing wastewater infrastructure to improve resilience, reliability and efficiency. This ongoing work helps reduce risk, manage costs, and ensure the system performs well over time. See our current projects.
Frequently asked questions
Who do I contact if I notice a wastewater spill or overflow?
If you see wastewater overflowing from a manhole, drain or pipe, contact your council as soon as possible so crews can respond quickly. Avoid contact with the wastewater and keep people and pets away from the area. Over time, customer services will transition to IAWAI. We’ll keep communities informed as these changes happen.
What should I do if my drains are backing up or blocked?
If wastewater is backing up inside your home or property, the issue may be in your private drain rather than the public network. In this case, you should contact a licensed plumber. If the problem appears to be in the street or public network (for example, overflowing manholes or drains), contact your council so they can investigate.
What should never go down the toilet or sink?
Only the three Ps should go down the toilet: pee, poo and (toilet) paper. Items like wipes, sanitary products, fats, oils, grease and food scraps can block pipes and damage the wastewater system. Even products labelled “flushable” can cause problems in the network.