Stormwater is rain water that runs across land, roofs and roads before returning to waterways. As it moves across these surfaces it can pick up sediment, litter, oil and other contaminants, meaning how it moves – and where it ends up – has a direct impact on homes, streets and the health of our rivers.
When stormwater systems work well, rain passes through communities with minimal disruption. We manage stormwater on behalf of our shareholder councils so communities are protected and waterways are cared for, even as conditions change.
What happens downstream
Unlike wastewater, stormwater isn’t treated in a treatment plant before it enters the environment. Instead, we rely on a mix of natural and engineered systems to slow the flow of water and remove contaminants before it reaches streams, rivers and the awa.
These include wetlands, detention ponds, rain gardens, filters and other treatment devices, as well as rain tanks that help capture and reuse water before it enters the network. Together, these systems help trap sediment, reduce pollutants and improve water quality.
By maintaining these systems and reducing what enters the stormwater network in the first place, we help protect downstream ecosystems, reduce flooding and erosion, improve bathing water quality, and ensure rainwater is safely returned to nature.
Our stormwater network
IAWAI is responsible for managing stormwater services across our region under contract for both Hamilton City Council and Waikato District Council. Together, we operate and maintain stormwater infrastructure across our rohe — replacing ageing assets, upgrading pipes and systems, and building new infrastructure to support population growth and climate resilience.
Our region’s stormwater system includes:
- Underground pipes and drains that collect and transport water
- Soak holes and swales that help water absorb back into the land
- Detention ponds and wetlands that slow stormwater down and remove sediment before it reaches waterways
A growing region, a changing climate
As our region grows, our stormwater network is under increasing pressure, both from urban development and tighter environmental regulations. We’re addressing this through a mix of new builds and upgrades:
- Establishing stormwater infrastructure in greenfield growth areas
- Erosion control and retrofitting treatment devices in established neighbourhoods
- Continuing work on integrated catchment management plans(ICMPs) to guide long-term planning
- Monitoring the health of our streams, rivers and stormwater outfalls
What you can do
Keeping our stormwater clean is a shared responsibility. What goes into a stormwater drain could end up in our awa, lakes or wetlands, so every small action counts.
You can help by:
- Avoiding dumping waste or chemicals into drains
- Washing vehicles on grass or at car washes
- Keeping gutters, driveways and grates clear
- Reporting blocked or overflowing stormwater drains