Flooding events along rivers and coastlines in the UK often hit the headlines, but less well publicised are problems with drought, which have put a severe strain on the water supply network.

The combined effects of population growth and climate change have fuelled a potentially disastrous situation, with resources in England in danger of running out in a matter of years if nothing is done to boost resilience.

By 2050, more than half of UK summers are expected to be hotter than the heatwave that scorched most of Europe in 2003, and during the same timeframe the population is set to rise to 75 million.

The Committee on Climate Change has predicted that demand for water in England will exceed supply by between 1.1 and 3.1 billion litres a day by the 2050s. Currently three billion litres, a vast 20 per cent of total supply, are lost every day through leakage from pipes.

James Bevan, head of the Environment Agency (EA), spelled out the gravity of the situation during his keynote speech at the Waterwise conference last year, when he warned that water shortages in England are set to become an “existential threat”. He said that within 25 years the country will reach the “jaws of death – the point at which, unless we take action to change things, we will not have enough water to supply our needs”.

Efforts to keep the water flowing will require a range of measures to cut demand, stem leakage, and boost supply and storage. A long-term plan, published by the EA in March, identifies potential interventions, including the construction of major infrastructure assets like reservoirs, effluent reuse and desalination plants. New pipeline projects may be required to support bulk water transfers between different localities, as well as infrastructure upgrades needed to halve water companies’ leakage rates by 2050.

The overhaul is likely to require a mix of hard civil engineering and smart digital technologies, such as the Internet of Things, big data, and digital twins, needed to add intelligence to legacy infrastructure, forecast potential climate impacts and assess the benefits of different measures. Consultants and water companies are already working to develop and implement solutions.

Oli Hawes, head of Mott MacDonald’s Smart Infrastructure business, tells E&T: “The industry is now able to build digital representations of all the fundamental information sources an engineer previously had to spend months or years collecting. In terms of water resources, it’s about digitising, from rain cloud to tap, all the constraints and inputs into the process, then layering on top analytics and driving down into where you will get the biggest bang for your buck in terms of investment, whether that means reservoir storage, or reduced leakage or other measures.”

Weather in the UK is becoming more extreme, with more heavy rain, flooding and droughts. Last year saw one of the most significant April storms in 50 years, with exposed locations in west Wales recording gusts of over 69mph, and when the mercury hit 38.7°C in Cambridge in July it was the highest temperature ever recorded in the UK.

The need to bolster drought resilience is recognised by the National Infrastructure Commission (NIC), which in 2018 made a series of recommendations to future-proof network infrastructure against climate change and drought.

These included a target to halve leakage by 2050 (which has been adopted by the regulator Ofwat and water companies), build additional supply infrastructure by the 2030s and create a national water transfer network to ensure an extra 4,000Ml/day of supply by 2050. The Commission has estimated that the cost to the country of not taking any action would be roughly double that of implementing measures to build resilience.

The EA’s new long-term National Framework for Water Resources will guide five recently-established regional groups, made up of the 17 English water companies, industry regulators, government and other water users, as they work up plans tailored to the specific needs of their areas. The solutions they devise will inform a national blueprint for water resources planning from 2025 to 2050.

Forging a clear way forward will be highly complex and there remains significant uncertainty around the likely impacts of drought and how severe and long-term they will be. Emerging digital technology can significantly improve the accuracy of impact forecasts, says Hawes: “As engineers we can build a digital representation of all the inputs, including long-term rainfall forecasting, environmental conditions, climate change, geology topology, hydro­geology and changes in usage, and codify the analytics of those input sources to provide more meaningful insight into what’s happening.”

An effective strategy for drought resilience must consider factors such as regional differences in water resources, population growth, and water demand driven by industrial developments and agriculture, as well as the nature of regulatory requirements placed on water companies.

A diverse set of measures bespoke to each region will be required. Trevor Bishop, organisational development director at Water Resources South East (WRSE), one of five new regional groups, says: “It’s about thinking very hard about how the water system and different infrastructure works in combination. If you have a gap between supply and demand, you could build more reservoirs. But if droughts become longer and more severe, those reservoirs could be empty before the drought is over, in which case, maybe you need to look at demand management combined with some reservoir storage, and some desalination and effluent reuse.”

The need for a mix of methods to manage different pressures is “going to be the big message in future”, he adds.

Part of the response will look at demand reduction and measures such as smart water meters and educating customers to conserve water. Thames Water is planning to install 700,000 domestic smart meters by 2025 to put domestic users in control of their water use.

Regional plans required under the new framework must show how to achieve, on average, 110 litres per person per day of water use by 2050, while also reducing non-household demand.

Meanwhile, major infrastructure projects could deliver a large hike in water capacity. Solutions on the table include several new reservoirs, such as Thames Water’s proposals to build a 150Mm3 ‘mega-reservoir’ in Abingdon, Oxfordshire in partnership with Affinity Water. Portsmouth Water is championing construction of a new reservoir to supply about 160,000 people in Havant Thicket, East Hampshire, targeted for delivery in 2029.

However, building reservoirs in the UK is notoriously difficult due to planning and legal hurdles and often fierce local opposition; for example, different versions of the Abingdon project have been circulating since 2006.

Desalination plants, which process salt water to make it suitable for human consumption or irrigation, pose an arguably greater engineering challenge due to their technical complexity and the UK’s relative lack of experience in building them.

Only one facility has so far been delivered, at Beckton on the lower Thames Estuary, to serve up to 400,000 households in London. Southern Water is now considering an option for a plant on the south coast with a capacity of 75 megalitres per day.

Desalination plants are typically expensive and involve energy-intensive production processes that may run counter to water companies’ carbon-reduction targets. Beckton is only designed to operate when London is in drought and has therefore remained idle for long periods.

Bishop says: “With these types of solution, there is a question around capacity and skills, both to plan and deliver desal plants and to run them afterwards. We need to think as a sector about whether we have enough engineers coming through the system.”

East and south-east England are generally the most water-stressed, and other areas of the country have surpluses, which opens the potential for water transfers between different regions to even out supply.

At present, just 4 per cent of supplies are moved between individual water companies, but the NIC has said this could be ramped up to produce about 700Ml/day additional capacity.

This approach could involve significant engineering and associated planning hurdles. Geraint Jones, technical director for water and energy at engineering consultancy Arcadis, says: “A client we are working with is looking at a huge bulk transfer option to deliver water a distance of approximately 100km, which is a huge undertaking that could mean threading large pipes through very sensitive areas of the country. The sector really needs to look at problems on a case-by-case basis. The solution might ultimately be a combination of desalination with measures to drive down water usage and leakage and small amounts of bulk transfer.”

Bulk water transfers run against existing regulatory, commercial and operating frameworks, which assume that infrastructure projects will be carried out by either a single water company or by water companies located next to each other.

To help smooth the planning of strategic infrastructure spanning multiple regions, as well as address any regulatory gaps or barriers, a new body, the Regulators’ Alliance for Progressing Infrastructure Development (RAPID), comprising Ofwat (the regulator for England & Wales), the EA and the Drinking Water Inspectorate, was established last year.

RAPID has made a funding pot of £470m available to nine water companies to develop joint solutions, including the creation of new water sources and transfers. One of the more innovative of the 17 options being proposed is a large-scale effluent reuse project at Mogden and Teddington. Thames Water’s scheme would dilute and recirculate a huge 300Ml/d of effluent from Mogden Sewage Treatment Works by passing it over Teddington Weir.

Bishop says: “The project could have a major impact on water supply, but it hasn’t gone forward yet and there are some issues with water temperature. It was too warm for the EA’s liking and could have affected fish migration. However, these types of reuse schemes have enormous potential for the future.”

Around 20 per cent of water put into the public supply is currently lost through leakage and Ofwat has set all water companies a target to bring down leakage by at least 15 per cent by 2025, rising to 50 per cent by 2050.

Emerging technology could help make this target a reality. Northumbrian Water is looking to work with several partners to use satellite positioning data to determine the amount of clay soil shrinkage around its buried assets. The shrinkage data can support proactive maintenance of pipes to prevent leakage, especially during extended dry periods.

Dr Angela MacOscar, head of innovation at Northumbrian Water, explains: “We experience an increased number of bursts during dry weather due to ground movement caused by soil moisture deficit. The satellite technology could help us understand the level of ground movement and be proactive in the maintenance of pipes that are vulnerable.”

Data from IoT sensors embedded into assets can help generate a more accurate and real-time picture of the state of assets in the network, which when overlaid with analytic processes can identify problems with leakage.

According to David Palmer, a director on Buro Happold’s water team, Thames Water is understood to be introducing an innovative programme to maximise water efficiency using a new digital platform. “A new command centre capability will increase mains monitoring by an estimated 25 per cent, which will allow live readings from up to 200,000 sewer monitoring points, helping to prevent pollution events. A smartphone app will link engineers to real-time, geo-referenced information.”

With multiple options for building water resilience on the table, questions remain over the extent of interventions and the cost of infrastructure and upgrades required.

Infrastructure measures outlined by the NIC in its plan are expected to be delivered by water companies through the regulatory process and Water Resource Management Plans, without extra funding from government. According to its calculations, the additional infrastructure would only cost consumers an additional £10 a year by 2050.

Others have questioned the efficacy of the proposals being put forward and the willingness of water companies to engage with them. A National Audit Office report examining Defra’s leadership of government and the water industry highlighted several concerns, including stalled progress over the past five years by water companies on tackling leakage, reducing water consumption, and in developing bulk water transfer solutions at the scale required.

Trade union GMB London Region has called for greater investment in large-scale infrastructure to collect, move and store rainfall in order to tackle periodic droughts.

Gavin Davies, senior organiser at GMB London Region, says: “Ofwat and Thames Water experts hide behind the false narrative that water is a scarce resource. They persistently and blatantly ignore all calls to implement the schemes identified by the Victorian engineers to have water available to deal with the very severe droughts that come along once or twice every generation.”

The five regional water groups were due to publish outlines for long-term resilience at the time of writing, with final plans due for publication in September 2023. As the clock moves on and global temperatures rise, stakeholders know they must act fast to keep the taps flowing.