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The heat is on: the importance of resilient water supplies

Whilst the recent warm weather has been a welcome treat for some of us, extended hot and dry periods put extra pressure on UK water supplies. Climate change is only adding to the problem. David Style says steps must be taken now, by regulators, water companies and individuals, to ensure the taps don’t run dry in the years ahead.

Last month was one of the warmest Junes since 1910. What’s not to like? It offered a great opportunity for people to go outside and enjoy the sunny weather. However, we are also seeing some of the downsides of higher temperatures and low rainfall. The low rainfall in June and stifling heat contributed to fires on Saddleworth Moor and Winter Hill, led to health warnings for vulnerable people, saw the River Teme dry up, leaving fish in need of rescue, and was linked to water supply interruptions in Northern Ireland and the Severn Trent region. A number of water companies asked their customers to reduce their water usage, warned of potential hosepipe bans and even set up bottled water collection points.

Hot weather encourages far greater household water use; whether it’s through keeping hydrated, staying cool, watering the plants or filling the paddling pool. Water companies expect this higher level of demand during summer months and try to manage their supplies accordingly. Typically, water companies plan to ensure their supplies are resilient to the worst historic droughts using records going back around 100 years. However, it’s likely that water supplies will be under greater pressure in the future due to the combination of population growth and climate change, which is linked to seasonal reductions in rainfall. So, if we want to avoid more frequent water shortages how much more water do we need in the future than we have now?

Research for a major report by the Adaptation Sub-Committee (ASC) in 2016 considered the gap between how much water we need and how much may be available in the future. It found that currently, on average, England has a surplus of water of around 1,400 million litres per day. However, depending on how much the population grows and the extent of climate change, by the 2050s we could see a deficit of between 1,100 and 3,100 million litres of water per day, and between 1,800 and 5,700 by the 2080s. That final number is equivalent to over 2,250 Olympic-sized swimming pools!

A recent report by the National Infrastructure Commission (NIC) also considered how much additional water England will need to be at least as resilient to droughts in future as it is now. Their answer was that we need another 3,000 million litres of water per day to make up for the effects of population growth and climate change, and then another 500 to 1,000 million litres of water per day if we want to be resilient to a more extreme drought (with a 1 in 17 chance of occurring by 2050). Although it only considered a medium emissions scenario, the report did consider a ‘drier’ climate change future and the total of 4,000 million litres per day the report recommends is roughly in keeping with the 2050s deficit suggested by the high population, high climate change scenario in the research for the ASC’s report.

These studies highlight the increasing challenges for water availability over the coming decades. Significant changes are needed and these will take time to implement so it’s important that we have clear targets to aim for, and that work begins soon. The ASC has previously highlighted the need for coordinated long-term action to manage water demand, reduce leakage and increase supply.

  • Our previous analysis suggests the uptake of cost-effective water efficiency measures could reduce household consumption to 115 litres per day. This could be achieved through simple steps such as installing low-flow taps, clicklock kitchen taps, dual-flush WCs and low-flow showers. Domestic water consumption was estimated to be 139 litres per day in 2015/16.
  • Water meters allow customers to pay for the water they use, rather than a flat rate tied to house size or value. This provides people with a financial incentive to reduce water use. If long-term trends in uptake of water meters were to continue, 85% of households would have a water meter by 2035 (compared to 45.4% today). If people install water meters at this rate, particularly in at-risk areas, this would help water companies to effectively manage supplies.
  • Around 3,000 million litres of water per day are lost from the system due to leakage from pipes. Whilst this has come down by about 2,000 million litres per day compared to 20 years ago, in recent years progress in tackling leaks has slowed. Water companies had collectively proposed to reduce leakage by 230 million litres per day over the period to 2040. This might be sufficient to deal with supply-demand deficits at the national scale (if we’re talking about low to medium levels of climate change), though not at the higher end. Ofwat, which regulates water companies, has since challenged them to reduce leakage by 15% between 2020 and 2025.
  • Implementing measures to reduce water demand alone is unlikely to reduce the risk of water shortages to an acceptable level in all locations, particularly if we’re talking about higher-end projections of more severe climatic change in the 2050s and 2080s. The supply of water can be increased by building new infrastructure such as reservoirs, re-using effluent (liquid waste or sewage discharged into rivers or the sea) and identifying new underground and surface water storage. As was demonstrated during the recent water shortages, it is not simply a case of having enough water but having it at the right times, and getting it through the system quickly enough to ensure that the places that need it most can access it. Therefore, coordinated, long-term planning, particularly given the amount of time it takes to build new infrastructure and identify new sources of water, is essential. Planning should also consider a wide range of ‘climate scenarios’ (low-, medium- and high-end) and seek to identify options that are able to manage future uncertainty.

A new ‘resilience duty’ on Ofwat will take effect in 2019 which means resilience, including to drought, will be formalised as an objective for the water industry. Developing metrics which give us an idea of resilience now and in the future are key to helping the country adapt to future water availability over time, and ensure the UK can deal with future uncertainty. If done right, we should all be able to have confidence in our water supply during even the hottest summers.

David Style is a Senior Analyst for the Adaptation Sub-Committee Secretariat


In 2019, the ASC’s Progress Report to Parliament will assess how water supply challenges are being addressed as part of the Government’s new National Adaptation Programme, which is due to be published in the coming months. We will also assess how the risk of water deficits is changing as part of our work on the third UK Climate Change Risk Assessment, due to be published in 2021.