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Managing stormwater to reduce pollution

Our proposed Stormwater Management Strategy describes how we will improve stormwater discharges over the coming decades. 

Wellington Water, and our communities, aspire to have healthy water in our waterways. In addition, Wellington Water is required to gain a resource consent from Greater Wellington Regional Council for stormwater discharged from the pipe network.

We’re in the process of applying for a long-term consent for stormwater discharges in Porirua, Wellington, Lower Hutt and Upper Hutt. The He Rautaki Wai Āwhātanga/Stormwater Management Strategy will underpin the resource consent.

If you have any questions about this work, please contact Wellington Water, 04 912 4400 or you can email us  at

Current status

The July 2023 proposed  Stormwater Management Strategy (SMS) is now available.


July 2023 update

The proposed SMS includes changes made as a result of public feedback in February 2023. We have refined the strategy, including the vision and objectives. We have clarified the work programmes. We have amended the SMS to acknowledge that to be successful the implementation of this strategy must be integrated with the management of sustainable water use, flood protection, wastewater management, urban growth and climate adaptation. We can help achieve the updated vision in this proposed SMS by working together to implement innovative solutions, promote community engagement and education, and invest in stormwater infrastructure.

The updated vision and objectives developed for this SMS are below:



Our region treasures its water. Our streams and harbours are healthy and suitable for contact recreation and Māori customary use. Our, drinking water is safe and secure, our networks are resilient, our growing cities are water sensitive, and we are prepared for a changing climate. Water is at the core of how we plan and grow our cities.



  1. Aquatic Ecosystem Health – Biodiversity, aquatic ecosystem health and mahinga kai in freshwater bodies and the coastal marine area are safeguarded from the adverse effects of stormwater discharges.
  2. Māori Customary Uses and recreational contact - Rivers, lakes, natural wetlands and coastal water where stormwater is discharged are suitable for contact recreation and Māori customary use.
  3. Sustainable Growth – Stormwater networks support well-functioning urban environments.




  1. Mahi tahi – working together
  2. Ki uta ki tai – integrated catchment management (that is, taking a holistic view from the mountains to the sea)
  3. Adaptive management – using monitoring, investigations and research to continually adapt and improve.


Find out more

Open the proposed Stormwater Management Strategy here.

Find out more by visiting the SMS Storymap.


Sub catchment plans

Central to the SMS are sub-catchment management plans. A sub-catchment is a neighbourhood or suburb that drains to a particular waterway. These management plans will identify ways to reduce contamination specific to that sub-catchment, drawing on a full range of options.


New developments and existing potential high-risk sites

The SMS requires the use of stormwater mitigations known as universal responses to minimise contamination from new developments and existing high-risk sites such as carparks and industrial sites.

In new developments this includes:


Water quality


avoiding copper and zinc contamination by not allowing exposed or untreated roofing, guttering or cladding made of galvanised steel or copper.





hydraulic neutrality; so that the development won’t result in increased downstream flooding or fast flowing water from our pipes that damages ecosystems in streams.






water sensitive design; using features such as wetlands and raingardens to manage flows and filter out contamination.






site-specific sub-catchment management plans for large new developments (over 3000 m2)







In high-risk sites this includes:

  • litter traps to reduce the amount of plastics and other pollution from washing into drains.
  • encouraging best practice in existing industrial and commercial sites to reduce or avoid contaminated runoff, including conducting audits and identifying remedial activities.


Existing urban areas

The SMS proposes working at the sub-catchment (neighbourhood or suburb) level to progressively reduce contamination from existing urban areas.

Our current stormwater programmes and planning on behalf of our councils are targeted at reducing the risk of flooding. The strategy expands that focus to include water quality across our work programmes:

·       Strategy and planning

·       Modelling and investigation

·       Design and construction

·       Operations and maintenance

·       Education, training and 


·       Data and asset management




We’ll work with communities to develop integrated sub-catchment management plans. These could include measures such as:

  • Reducing contamination at source (e.g. find and fix cross-contamination, information and education for residents)
  • Capturing and treating stormwater (e.g. wetlands, rain gardens where plants can filter out contamination)
  • Supporting local initiatives (e.g. planting to reduce stream scouring).


We can’t do everything at once so we will have to prioritise the development of sub-catchment management plans.  There’s more about sub catchments in the story map here. 

We’re proposing to work with councils and mana whenua, with input from communities, to sequence sub-catchments in the short, medium and long term. 



We have to shift the way we manage rainwater that falls on urban areas, on behalf of councils, to help reduce pollution of our harbours, rivers and streams.

Over decades, a network of stormwater drains and pipes has been built to carry rainwater quickly into waterways or the sea, to reduce the risk of flooding. 

Now, as well as carrying the water away, we also need to reduce pollution such as litter, fertiliser, heavy metals and bacteria that stormwater carries.

We're developing a strategy to support our application for a global stormwater discharge consent that will help us to move towards healthy water over the coming decades.


What we do

At Wellington Water, we manage the public urban network of pipes and drains that collects and carries stormwater away from built up areas on behalf of councils.

We now have to do this in a way that gives effect to Te Mana o te Wai and meets national and regional rules and regulations. This includes getting approval from Greater Wellington Regional Council, in the form of a resource consent, to discharge stormwater and the pollutants it contains into natural waterways such as streams, rivers and harbours.

We currently have a short-term consent and in mid-2023 lodged an application for a long-term consent.

Regional Council

Greater Wellington Regional Council sets out the rules and requirements for discharges to land and water in the Natural Resources Plan for the Wellington Region. It has worked with mana whenua and community representatives in each Whaitua, or catchment, to develop plans to restore wai ora (healthy water) in the next 100 years.

Find out more on the GWRC website here 

Mana whenua engagement

We are engaging with mana whenua on the proposed Stormwater Management Strategy:

  • Ngāti Toa represented by Te Rūnanga o Toa Rangitira (primary location: Porirua, Wellington, Te Awa Kairangi)
  • Taranaki Whānui ki te Ūpoko o te Ika a Maui represented by Port Nicholson Block Settlement Trust (primary location: Wellington, Te Awa Kairangi and Wainuiomata).



We are working with our client councils on the development of the proposed Stormwater Management Strategy:

  • Wellington City Council
  • Porirua City Council
  • Hutt City Council
  • Upper Hutt City Council


South Wairarapa District Council is at an earlier stage on its stormwater journey and we expect to start collecting information about the impacts of stormwater on Wairarapa waterways in the near future.

Proposed stormwater management strategy