Central Interceptor
The largest wastewater project in New Zealand, our super-sized tunnel will run for 16.2kms under Auckland city and the Manukau Harbour. Find out what it’s all about and how we’re tracking.
Duration
2019-2026
Location
Herne Bay to Māngere
Status
Construction
Ground-breaking benefits for Tāmaki Makaurau
Since 2019 we’ve been busy constructing New Zealand's largest wastewater tunnel to manage our central city’s wastewater, called the Central Interceptor (or ‘CI’). It’s all about everyone enjoying cleaner inland waterways and open spaces across the central city.
Right now, in older parts of the city, wastewater and stormwater flow into a combined network of pipes. When it rains heavily, stormwater often overwhelms the ageing system, resulting in wastewater overflows into our creeks and streams.
The CI tunnel will significantly reduce overflows in the central Auckland area.
See how far we've tunneled
Take a look at the progress of our Tunnel Boring Machines
What are we building under there?
Once completed in 2026, the tunnel will lie between 15 and 110 metres below the city surface and run all the way from Herne Bay to Māngere.
With a diameter of 4.5m, the tunnel will be high enough to fit a standing giraffe inside.
Along with two smaller-link sewer tunnels also under construction, the main CI tunnel will collect wastewater from the existing network and take it to the Māngere Wastewater Treatment Plant – with a controlled flow rate. The tunnel slopes at a gradient of 1:1000 so wastewater can flow downhill to Māngere.
The budget for this epic seven-year project is $1.5 billion.
Did you know?
The CI tunnel has capacity to store more than 250,000 cubic metres of wastewater - that’s 99 Olympic swimming pools. Read more in our project brochure.
Want to know more?
Want to know more?
![Photo of the Central Interceptor mobile Discovery Centre.](https://promising-sparkle-d7f0c0cfc9.media.strapiapp.com/discovery_centre_6_new_134470b517.jpg)
Check out our travelling Discovery Centre
Grab the whanau and join us for an awesome experience including virtual reality, outdoor games and a movie ride to learn all about the CI tunnel. The list below details where the Discovery Centre will be throughout August.
- Sat 17 Aug, 1pm-4pm: ‘Get to know the Whau’ Expo, New Lynn Community Centre, Totara Avenue
- Sun 18 Aug, 10am-4pm: MOTAT Live
Construction updates
We have 17 construction sites along the tunnel route, with some operating for three to five years, with smaller sites open for around 24-36 months.
At the bottom of the page, you can see what’s going on at each site.
The technology behind New Zealand’s largest wastewater project
To dig the main CI tunnel and lay the concrete segments behind it, we’re using state-of-the-art tunnel boring machines or TBMs. These gigantic machines enable us to excavate (or ‘bore’) through a wide range of ground conditions.
Infrastructure constructed by these powerful TBMs is strong and reliable and is set to last at least 100 years.
![Photo of the tunnel boring machine Hiwa-i-te-Rangi being unveiled.](https://promising-sparkle-d7f0c0cfc9.media.strapiapp.com/CI_TBM_namimg_14dec_2020_DSCF_2372_5674d818e4.jpg)
Meet Hiwa-i-te-Rangi: a truly ground-breaking machine
Hiwa-i-te-Rangi is the giant TBM working tirelessly to grind a 16.2 km journey, using her massive cutter head.
TBMs are traditionally given female names in honour of the patron saint of miners and tunnellers, Saint Barbara.
To find a name for our main TBM, we asked for ideas from children in schools along the tunnel route. They chose Hiwa-i-te-Rangi, a female Matariki star, which they believed represented our aspiration to improve the natural environment.
Hiwa-i-te-Rangi is in great company, working alongside our smaller TBMs, Dominica and Victoria (and our training TBM, Kate).
Did you know?
We truck up to 5,000 cubic metres of rock and soil (or ‘spoil’) each week – that's enough to fill up more than 150 six-metre-long sea containers. Most of the spoil is taken to Puketutu Island in Māngere to help restore the original volcanic cone. One day, this island will be opened to the public as a regional park.
Engaging with locals
We want to update you on the construction process and hear your feedback. If you live or work near one of our sites, you’ll get a bulletin, newsletter, notice or letter, or an invitation to a public event, depending on the information we have to share.
You can also come along to our interactive travelling Discovery Centre to know more about what’s going on and have some fun at the same time (details above). Email us your feedback.
Protecting our environment
As well as delivering significant environmental benefits such as cleaning up our waterways, we’re committed to leaving our construction sites and their surrounds in a better condition than when we arrived.
Learn more about our plans, initiatives and practical actions in the areas of sustainability and the environment.
Supporting our wider community
Although it’s being built to last 100 years, the ambition for the project extends well beyond construction. We also want to help improve the well-being of communities along the tunnel route.
To support this, a cultural outcomes group is providing advice as the project progresses. This group comprises people from Mana Whenua, our Watercare team and contractors. Check out some of our activities.
Updates from our sites across Auckland
Dundale Avenue - Construction began: July 2020 Location: Road Reserve near 66 Dundale Avenue, Blockhouse Bay, Auckland 0600
Dundale Avenue is the launch site for the smaller tunnel boring machine that will take flows from the Western Interceptor and connect them to the new Central Interceptor tunnel at May Road.
Bulletins
Sign up for the latest news
Sign up to our Dundale Avenue Bulletin, so you know what’s happening throughout the project.
Location: Road Reserve near 66 Dundale Avenue, Blockhouse Bay, Auckland 0600
Dundale Avenue is the launch site for the smaller tunnel boring machine that will take flows from the Western Interceptor and connect them to the new Central Interceptor tunnel at May Road.
Bulletins
Sign up for the latest news
Sign up to our Dundale Avenue Bulletin, so you know what’s happening throughout the project.
Frederick Street (PS23) - Construction began: July 2021 Location: 39 Frederick Street, Hillsborough, Auckland 1042
Bulletins
Read the latest Frederick Street bulletin
Sign up to our Frederick Street bulletin, so you know what’s happening throughout the project.
Location: 39 Frederick Street, Hillsborough, Auckland 1042
Bulletins
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Sign up to our Frederick Street bulletin, so you know what’s happening throughout the project.
Haverstock Road - Construction began: April 2022 Location: 98 Haverstock Road, Sandringham, Auckland 1025
Bulletins
Read the latest issue of the bulletin
Sign up for the latest news
Sign up to our Haverstock Road bulletin, so you know what’s happening throughout the project.
Location: 98 Haverstock Road, Sandringham, Auckland 1025
Bulletins
Read the latest issue of the bulletin
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Sign up to our Haverstock Road bulletin, so you know what’s happening throughout the project.
Haycock Avenue - Construction began: May 2020 Location: 4 Haycock Avenue, Mt Roskill, Auckland 1041
Bulletins
Read our latest Haycock Avenue bulletin
Sign up for the latest news
Sign up to our Haycock Avenue bulletin, so you know what’s happening throughout the project.
Location: 4 Haycock Avenue, Mt Roskill, Auckland 1041
Bulletins
Read our latest Haycock Avenue bulletin
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Sign up to our Haycock Avenue bulletin, so you know what’s happening throughout the project.
Keith Hay Park - Construction began: January 2020 Location: 22 Gregory Place, Mt Roskill, Auckland 1041
Bulletins
Read the latest Keith Hay Park bulletin
New CI project
We are beginning construction on a new extension to CI in the Park, to cater for future growth in the area. Read more.
Sign up for the latest news
Sign up to our Keith Hay Park Bulletin, so you know what’s happening throughout the project.
Location: 22 Gregory Place, Mt Roskill, Auckland 1041
Bulletins
Read the latest Keith Hay Park bulletin
New CI project We are beginning construction on a new extension to CI in the Park, to cater for future growth in the area. Read more.
Sign up for the latest news
Sign up to our Keith Hay Park Bulletin, so you know what’s happening throughout the project.
Lyon Avenue - Construction date: May 2022 Location: 30-36 Alberton Avenue (near Lyon Avenue & Morning Star Place), St Lukes, Auckland 1025
Bulletins
Read our latest Lyon Avenue bulletin
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Sign up to our Lyon Avenue bulletin, so you know what’s happening throughout the project.
Location: 30-36 Alberton Avenue (near Lyon Avenue & Morning Star Place), St Lukes, Auckland 1025
Bulletins
Read our latest Lyon Avenue bulletin
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Sign up to our Lyon Avenue bulletin, so you know what’s happening throughout the project.
Māngere Pump Station - Construction began: August 2019Location: Māngere Wastewater Treatment Plant, Māngere, Auckland 2022 (access via Island Road or 75 Greenwood Road)
Bulletins
Read the latest issue of the Māngere Pump Station bulletin
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Sign up to our Māngere Pump Station bulletin, so you know what’s happening throughout the project.
Location: Māngere Wastewater Treatment Plant, Māngere, Auckland 2022 (access via Island Road or 75 Greenwood Road)
Bulletins
Read the latest issue of the Māngere Pump Station bulletin
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Sign up to our Māngere Pump Station bulletin, so you know what’s happening throughout the project.
May Road - Construction began: August 2019 Location: 54 Roma Road & 105 May Road, Mount Roskill, Auckland 1041
Bulletins
Read the latest issue of the bulletin
Sign up for the latest news
Sign up to our May Road bulletin, so you know what’s happening throughout the project.
Location: 54 Roma Road & 105 May Road, Mount Roskill, Auckland 1041
Bulletins
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Miranda Reserve incl PS25 - Construction began: 29 September 2020 (Blockhouse Bay Road site) and November 2021 (PS25 site) Location: Miranda Reserve, Avondale, Auckland 0600
Bulletins
Read the latest issue of the Miranda Reserve incl PS25 bulletin
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Sign up to our Miranda Reserve bulletin, so you know what’s happening throughout the project.
Location: Miranda Reserve, Avondale, Auckland 0600
Bulletins
Read the latest issue of the Miranda Reserve incl PS25 bulletin
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Mt Albert War Memorial Reserve - Construction began: May 2022Location: 7 Wairere Avenue, Mt Albert, Auckland 1025
Bulletins
Read the latest issue of the bulletin
December 2023 issue, click here
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Sign up to our Mt Albert War Memorial Reserve bulletin, so you know what’s happening throughout the project.
Location: 7 Wairere Avenue, Mt Albert, Auckland 1025
Bulletins Read the latest issue of the bulletin
December 2023 issue, click here
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Sign up to our Mt Albert War Memorial Reserve bulletin, so you know what’s happening throughout the project.
Norgrove Avenue - Construction began: November 2022Location: Road - Norgrove Avenue (near 14-16) & 17C Verona Avenue, Mt Albert, Auckland 1025
Bulletins
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Location: Road - Norgrove Avenue (near 14-16) & 17C Verona Avenue, Mt Albert, Auckland 1025
Bulletins
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Rawalpindi Reserve - Construction began: October 2022 Location: 9A Rawalpindi Street, Mt Albert, Auckland 1025
Bulletins
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Location: 9A Rawalpindi Street, Mt Albert, Auckland 1025
Bulletins
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Tawariki Street, Grey Lynn - Construction began: 2023 Location: 44-48 Tawariki Street, Ponsonby, Auckland 1021
Bulletins
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Location: 44-48 Tawariki Street, Ponsonby, Auckland 1021
Bulletins
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Walmsley Park - Construction began: December 2020Location: 727-761 Sandringham Road Extension, Mt Roskill, Auckland 1041
Bulletins
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Location: 727-761 Sandringham Road Extension, Mt Roskill, Auckland 1041
Bulletins
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Western Springs - Construction began: 2022 Location: 731 Great North Road (Stadium Road), Grey Lynn, Auckland 1021
Bulletins
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Location: 731 Great North Road (Stadium Road), Grey Lynn, Auckland 1021
Bulletins
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Pt Erin - Construction began: June 2024Location: Pt Erin Park, 94 Shelley Beach Rd, Herne Bay, Auckland 1011
Bulletins
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Location: Pt Erin Park, 94 Shelley Beach Rd, Herne Bay, Auckland 1011
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