Wastewater is often called sewage. It is water that goes down sinks, drains from washing machines, showers and baths, and is flushed away in the toilet.

Wastewater passes into a pipe on your property on its way to join our network, where we thoroughly treat and dispose of it in an environmentally conscious way. It's a big job which requires some pretty impressive infrastructure, innovative systems and dedicated people to deal with the sheer volume of wastewater arriving at our treatment plants from across the Auckland region. 

Watch the video below on how we treat your wastewater

How we manage our wastewater networks

Our engineers and maintenance crews operate and maintain our wastewater network which includes 18 treatment plants, 518 pump stations and more than 8,000km of pipes.  

Overflows can occur when pipes become blocked or overwhelmed with stormwater. When this happens, our maintenance crews respond quickly and carry out a thorough clean of the affected area. Find out what you can do to reduce overflows.  

Who is responsible for our wastewater and stormwater?

Stormwater is rain that isn’t absorbed by the ground. It needs to be collected so it doesn’t cause flooding. It flows from downpipes and stormwater drains directly into the public stormwater network which flows untreated into the streams and sea. Auckland Council manages the Auckland stormwater network. 

Wastewater (sewage) is the used water from sinks, washing machines, showers, baths and toilets. Most of it is water, but it also contains organic matter such as human waste, food scraps, cooking fats and oils, and debris such as sand and plastic. Wastewater drains into gully traps and private wastewater pipes on your property. These connect to our public wastewater network which carries your household wastewater to treatment plants. 

Peek inside our Māngere Wastewater Treatment Plant 

Above: before treatment, raw wastewater goes through screens to filter out any solids such as rags, debris and other objects. Rotating drum screens feed this material into a conveyor and deposit it in a large bin. Trucks then take it out to landfill.

Above: before it leaves the treatment plant, the liquid is disinfected under powerful ultraviolet lamps.  This results in a 10,000-fold reduction of harmful pathogens, bacteria and viruses. There are no chemical byproducts, and it is safe for the environment.

Māngere and Rosedale treatment plants treat more than 90% of Auckland's wastewater.

'Wondering about wastewater?' pdf

Māngere and Rosedale treatment plants treat more than 90% of Auckland's wastewater.

Take a closer look at the fascinating steps involved in preparing this wastewater to be safely released back into the environment.


Wastewater treatment is a complex yet interesting and evolving process. Find out more about the people and projects behind the scenes.