Stormwater, wastewater and climate change: Impacts on our economy, environment, culture and society

View from inside a sewer out onto the beach

In October 2017, the Deep South Challenge released a report into the state of the nation’s storm and waste water infrastructure, in the face of a changing climate. The report garnered significant media attention – not surprising given the infrastructure is currently valued at well over $20 billion.

The report gathered together what we already know about how climate change is likely to affect our stormwater and wastewater systems:

  • Sea level rise will affect all coastal infrastructure and will likely result in increasing sewage overflows, pipes corroded by salt water, and exposure to liquefaction.
  • More severe and more frequent coastal storms will affect infrastructure, causing increasing inundation, physical damage and electrical failure at treatment plants.
  • Changes in extreme rainfall will overwhelm the networks, restricting opportunities for maintenance, and increasing the infiltration of wastewater into stormwater (with concerning flow on effects for health, ecology, cultural and recreational spaces, and water supply for drinking).
  • Drought will also affect networks, disrupting gravity systems by slowing flow and leading to blocked pipes.

The report also highlighted significant gaps in our knowledge about how climate change might impact our stormwater and wastewater infrastructure, as well as in our understandings about the extent to which damage to this infrastructure might impact our economy, environment, culture and society.

The Deep South Challenge, through our Impacts and Implications programme, is now investing in research that seeks to fill these knowledge gaps.

We’ve just funded a new research project lead by consultants Tonkin + Taylor, called “Stormwater, wastewater, climate change: Impacts on our economy, environment, culture and society”. Over one year, this project aims to explore these potential impacts and to develop a detailed “theory of change”. The project is based on the idea that only once we have determined the performance we require of our storm and wastewater network in a changed climate, as well as the full range of likely impacts, can we design an efficient and effective solutions pathway.

Project leader James Hughes says, “Aside from the obvious impacts we are aware of, and those we are beginning to understand, there is so much that we actually don’t know. For someone working in this field this can be both very worrying and intriguing at the same time!”

This project will involve a comprehensive review of New Zealand and international literature, including local and regional case studies, as well as a detailed process to gather end user needs and requirements, via a panel of a key experts, including iwi representatives. 

Those key experts include Blair Dickie (Environment Waikato), Gavin Palmer (Otago Regional Council), Iain White (Waikato University), Jackie Colliar (NIWA, Waikato Tainui), Mark Bishop (Watercare), Noel Roberts (Water NZ), Sue Ellen Fenelon (Ministry for the Environment), Tumanako Faaui (Ngāti Whakahemo), and Tom Cochrane (Canterbury University).

The research intends to produce a summary of the physical impacts of climate change on storm water and waste water systems, and related outcomes across social, environmental, cultural and economic domains; a summary of how these outcomes may vary across New Zealand and where these may be more likely to occur; and some guiding principles for practitioners and decision-makers in the planning and engineering sectors.

James Hughes continues: “The outcomes of research like this can have potential to offer some really practical outcomes for New Zealand towns and cities, which is what we will be aiming to achieve.”

The research team combines excellence in engineering, economics and physical science – and comprises experts from Tonkin + Taylor, NIWA and Infometrics. For more information about the Deep South Challenge (and particularly our Engagement and Impacts & Implications programmes), check out our website: