Prof David Butler: Water Resilience


David Butler is Professor of Water Engineering at the University of Exeter and a Director of the Centre for Water Systems.  He was elected a Fellow of the Royal Academy of Engineering in 2015. He specialises in urban water management, has authored/co-authored over 250 technical papers, in addition to 12 books, published reports and edited conference proceedings, and is co-editor-in-chief of the Urban Water Journal.  He has been funded without interruption by the UK Engineering & Physical Sciences Research Council since 1995 and is an EPSRC established career research fellow (2013-2018). 

Resilience is the ability to bounce back and cope with adverse or extreme events. Resilience and sustainability are different - they are dependent on each other but not the same thing. Something may be resilient but not sustainable. Resilience is also about adapting forward, imagining a different way of organising ourselves and society.

There are the time and financial dimensions to resilience as well, which means a cost-benefit dimension which influences the choice to be resilient or not.

Recommendations to OFWAT:

  • Resilience is a new word or phrase and will require new parameters/variables e.g. time to recover, time of no-trouble, exposing systems to different stresses to determine capacity to cope.
  • Security of supply is the Water companies’ main strategy especially where there is single supply.
  • There are different scales and scope of demand; Infrastructure v. Performance and the measure could be that x amount of dual supply areas in a water company catchment.   There are social dimensions to resilience as well.
  •  What defines water security?  What is different with resilience?
  • Readiness could be a measure of resilience.
  • Should resilience be measured in a statistical way? Risk-based approaches rely on the likelihood of events etc.  Unfortunately, for extremes and shocks, the probability is unknown.
  • Adequacy of preparation and influence on spend and investment.

Does water efficiency fit in with resilience? How?

  • For example, if there is a drought event, being water efficient helps to be more resilient but this is not necessarily the case and there is the need to explore the trade-off space between the two.  However, water efficiency helps to promote social resilience; it is people who use water, not water companies, so water resilience is about how resilient individuals are.
  • Water efficiency is all about non-essential restrictions during droughts but this is not being resilient and actually a failure; so is resilience more about the long term provisions to avoid those restricted situations?
  • Resilience is about managing beyond failure and dealing with unknown unknowns.  When talking about resilience, it is important to talk about "of what, to what" and being water efficient does not necessarily prepare one for an extreme event; which by its' very nature is extreme. Resilience from an ecological point of view shows that more connected and diverse systems can be very resilient; but this is also not necessarily the case, a connected system exposes to other risks e.g. in extreme cases – terrorism.
  •  Resilience is also about being resilient to the future but who pays? The water company or the customer? OFWAT, the regulator, like to keep water bills low for the customer which makes it difficult to implement big schemes.  Maybe the government can find tools e.g. tax revenues to deal with really stressed areas e.g. the South East. Ultimately, we all will.
  •  In Australia there are 3 tiers of government, resilience depends on area and extent of cooperation between the levels of government.
  • Maybe the need for water companies to provide constant supply to meet demand makes us in itself non-resilient.
  • Who protects us and helps to make us resilient? The water company assures supply to a point and then something else takes over. The same as floods, government to a point, then insurance takes over. The key thing is understanding the trade-off between the different parties; maybe there is no additional cost for resilience and it's all taken care of!


  1. Need to develop resilience- prepare for the unpredictable future.
  2. A key component of resilience is adaptability –we also need to try to find a different way of organising ourselves which can work towards sustainability
  3. Look to improve what we already have in place. Need to get to a situation where our expectations match what we can do.
  4. If you were OFWAT what would you require of the water companies to demonstrate that their water resilience is improving? Working on water demand management – exposing systems to different stresses – need to define water resilience.
  5. What elements need to be considered? Security of supply; establishing where there is only a single source of supply; there is currently high investment in dualling supplies; what is more of interest to OFWAT are preventative measures rather than performance measures.  OFWAT want to see what percentage of water companies’ pipelines are dual supply. 
  6. Need to identify what is water security; most water companies will have water service plans but how ready are they in the case of emergencies?  Resilience should be included in water demand plans.
  7. Perhaps rainwater harvesting can contribute towards more water resilience?  By using redundant water capacity this would reduce the need to explore for more water sources in the future?
  8. Water companies need to look at how they engage their customers; people use water so how can we transfer ownership? How resilient are people to too little and too much water? Future proofing?
  9. Another key component of resilience is diversity - We don’t know what the future may hold.
  10. We need to look at other countries such as Australia and the lessons learned.