Desalination is one of the most contested questions in the UK water system. 

The case for it is simple. The country is facing a projected water supply shortfall due to climate change and other risks.

"We're no longer planning for average conditions," Valerie Robertson, senior associate director of environmental economics at Jacobs and a speaker at the upcoming Water, Wastewater and Environmental Management (WWEM) Expo, says. "We're planning for increased drought risk, population growth, tighter environmental expectations and greater uncertainty."

Still, UK desalination projects are expensive and energy-intensive, face environmental opposition, and have a slow planning and permitting process. The mainland's sole large facility, the Beckton plant, doesn't help its case. It cost millions of pounds to set up, but has produced only a week's worth of water in 15 years. 

Ahead of the 2026 Water, Wastewater and Environmental Management (WWEM) Expo, we assess the case for desalination in the UK and review current and planned projects that will determine its role in the country's future water strategy.

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What Is Desalination? 

Desalination is a process by which salt and other dissolved minerals are removed from seawater or brackish water to produce fresh water clean enough to drink. The technology is widely employed around the world, but it's underused in the UK because it hasn't been required until now. 

How does desalination work?

Desalination generally works through membrane processes — more precisely, through reverse osmosis (RO). In RO, water is forced under high pressure through a thin semi-permeable barrier that lets water molecules pass but not salt.

RO uses much less energy per cubic metre of water than the other main desalination process, thermal distillation (evaporation), through which seawater is boiled and condensed as pure steam.  

Thermal distillation is a defining feature of older systems and can be economically advantageous when energy is cheap or when waste heat is available: in a power station, for instance. Most of the world's thermal plants are located in the Gulf states.

Why Has the UK Historically Avoided Desalination?

Abundant rainfall

The UK is known for high rainfall. The temperate, wet climate supports a wide network of rivers and aquifers. Industry simply hasn't needed to invest its resources in a complex process like desalination when nature has supplied water for free. 

Cost and energy concerns

Desalination projects are expensive to create and run. The only large plant on the UK mainland, Thames Water's Beckton, was built in 2010 at a cost of £270 million. A Jersey plant cost around £180,000 in energy and manpower to run over two months in summer 2025. And this, says the island's operator, is the cheapest option available for a small island. 

Environmental considerations

Removing fresh water leaves a concentrated brine, about twice as salty as seawater, which usually ends up back in the ocean. This brine must be diluted; otherwise, the dense discharge sinks and can harm marine life. Treatment chemicals like antiscalants and chlorine are another concern; their intake can attract fish and larvae.

Why Is Desalination Back on the UK's Agenda? 

The UK's growing water supply gap

Water is facing increasing pressure across the UK. On the one hand, a growing population, housing, data centres and industry are pushing up demand. On the other, the country is facing less reliable rainfall, raising the risk of droughts like those of 2022 and 2025. 

At this rate, the Environment Agency (EA) projects a daily shortfall of 5 billion litres of water for public supply by 2055 — a third of its current daily use — and of 1 billion litres a day for economic activities like growing food and generating energy. 

Tightening abstraction limits

The UK has met most of its needs by abstracting water from rivers and aquifers. But over-abstraction has damaged rivers and chalk streams, and regulators are cutting back.

The EA is reducing licences where abstraction causes the most ecological damage, and the government's "New Vision for Water" White Paper moves abstraction into the Environmental Permitting Regime to further tighten control, targeting high-volume users in critical areas such as the South East. 

As a substitute, authorities are increasingly considering desalination.

"Desalination is a useful option as part of a diverse range of water supply projects … to ensure that our water supply is climate-resilient. Unlike many traditional sources, desalination does not depend on rainfall, meaning that supply is protected during periods of drought," writes Ofwat.  

Policy and investment shifts

For water companies, the regulatory and investment landscape is being redrawn.  

The White Paper sets aside over £104 billion for infrastructure improvement between 2025 and 2030. It also streamlines planning for major projects and proposes replacing a patchwork of regulators with a single one that abolishes Ofwat.

Large desalination schemes now run through the Regulators' Alliance for Progressing Infrastructure Development (RAPID), which fast-tracks strategic water projects, and whose role the White Paper has endorsed and proposed expanding. 

A House of Commons Library research briefing from July 2025 said nine new desalination plants were included in water companies' water resource management plans (WRMPs). The plants themselves are years away — most won't begin construction until the 2030s — but the decisions that will get them built are being made now. 

Live and Proposed UK Desalination Projects at a Glance

There are 22,000 desalination plants in 170 countries, yet the UK and Channel Isles have only three, with more in planning stages. 

• Beckton Desalination Plant. This plant, built in 2010 with a capacity of 150 Ml/d, can process brackish water from the River Thames through a four-stage RO system. But it has only run five times since, producing seven days' worth of water. Once its full lifetime bill is counted, that works out at roughly £0.07 a litre — 28 times the typical cost of mains supply. It's currently inactive, hampered by chemical leaks and carbon dioxide-sourcing problems for remineralisation, and pending approval for new membranes. 
• Jersey Water Plant, Channel Islands. Operational since 1970, the La Rosière plant was converted from thermal distillation to RO in 1999. It's currently undergoing a £26 million upgrade to increase output by 50%. It provides 10.8 million litres of water daily at a cost of £5,000–£8,000 a day. 
• South West Water, Isles of Scilly and St Austell Bay. A plant on St Mary's has supplied water to the Isles for decades. It provides around 40% of fresh water, with the rest coming from groundwater. In 2018, it was refitted with two new 200 m³/day RO trains. South West Water says it's "excited about introducing desalination on the mainland and the other four islands." At Par, South West is pursuing desalination in two phases, with Veolia as its technology partner. Phase 1 is a small, container-based plant producing up to 2.5 million litres per day, designed to avoid new marine pipelines, and is currently undergoing planning and public consultation. Phase 2 — up to 20 Ml/d, designed as a "turn on/turn off" drought resource — is stalled. The Marine Management Organisation (MMO) rejected its survey-drilling licence application, ruling that it didn't contain enough environmental and technical information, and campaigners have protested it over its potential adverse impacts on seagrass, maerl and protected seahorses. The company says it plans to reapply for a licence. 
• Anglian Water, East of England. The company is moving forward with three coastal desalination schemes at Holland-on-Sea (Essex), Bacton (Norfolk) and Mablethorpe (Lincs.) They have a combined assumed supply of 140 Ml/d targeted for 2040. Typsa-Stantec-Acciona will join as a technical partner. The schemes have secured development funding through Ofwat's PR24, including £77 million for Bacton and £72 million for Mablethorpe. This is within a wider, privately funded desalination vision that a Global Water Intel report put at £1.7 billion in December 2024.
• Southeast England Plants. Water Resources South East (WRSE), the alliance of the six water companies that cover the South East region of England, has plans for six plants to be built in Kent and West Sussex between 2040 and 2075:
  • Thames estuary, delivering 40 Ml/d by 2040
  • East Thanet coast, delivering 20 Ml/d from 2041 and 40 Ml/d by 2050
  • Isle of Sheppey, delivering up to 20 Ml/d from 2041 and 30 Ml/d by 2063
  • Reculver, delivering 30 Ml/d by 2044
  • Tidal River Arun, delivering 40 Ml/d by 2050
  • Hythe, delivering 5 Ml/d by 2050

Rather than a single flagship project, the key development is the growing participation of multiple water companies in assessing desalination as a future water supply option.

"That demonstrates a broader shift in thinking that resilience requires a portfolio approach," Robertson says. "Anglian Water's work is noteworthy because it is exploring desalination alongside advanced water reuse, recognising that many of the technologies, such as reverse osmosis, energy recovery and membrane treatment, are complementary and can support a wider portfolio of resilient supplies."

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The Ongoing Challenges of Desalination

Cost, energy and carbon 

Desalination's defining drawback is energy.

RO needs about 3.65 kWh to produce a cubic metre of water, according to manufacturer Danfoss. That's far more energy than treating river or groundwater. Thermal methods use even more energy: multi-effect distillation uses 4-10 times as much energy as RO, and multi-stage flash uses up to 22 times as much.

Along with staffing, energy consumption drives up the running costs of plants versus more traditional methods, as the Jersey example shows. The capital cost is also high.

Regarding carbon costs, Danfoss puts it at around 1.5 kg CO₂/m3 per litre. Estimates vary wildly, though. According to their own analysis, other researchers have put RO's footprint anywhere between 0.4 and 6.7 kg CO₂/m3. 

But new UK schemes are being designed to run on clean power. South West Water's planned Par plant, for instance, will operate under a 100% renewable electricity contract with inbuilt energy-recovery systems, in line with the company's net-zero-by-2030 commitment. On-site generation is under consideration. This method is becoming the norm, which has helped weaken the carbon objection.

Ultimately, the issue is that desalination goes in the opposite direction of where the industry is trying to go. Many water companies are targeting net-zero. They are cutting leaks, introducing metering and strengthening efficiency and recycling. Meanwhile, desalination increases energy demand per litre. 

Environmental impact and permitting

Desalination in the UK is highly regulated, and a coastal plant must clear several approval systems. The marine works (intake and pipelines) need a licence from the MMO; the brine discharge needs an environmental permit from the EA; and plants drawing on tidal or brackish rivers, rather than the open sea, may need an abstraction licence. Regulators then monitor ongoing performance against statutory requirements. 

Utilities must also get approval from the Drinking Water Inspectorate confirming that the proposed membrane will supply safe drinking water under Regulation 31. 

"The biggest influence on desalination deployment will be how regulators balance water security with environmental protection," Robertson says. "As abstraction constraints tighten to protect rivers and ecosystems, alternative sources such as desalination become increasingly important, but regulatory clarity around drinking water approvals, environmental permitting and long-term resilience outcomes will be essential to give water companies confidence to invest."

Public acceptance and planning 

Facilities need approval from either a local authority (planning) or via the Planning Inspectorate to the Secretary of State (a development consent order). The latter applies to plants with more than 80 Ml/d of "deployable output" — the average a plant can produce under drought conditions.

Most planned UK schemes fall below this threshold and must be reviewed by local planning authorities. This is why local opposition, such as in St Austell, carries so much weight.

Desalination, Water Recycling or Reservoirs: How Does the Sector Choose?

Desalination is one tool in a wider toolkit for the UK to address ongoing water issues, and it's unlikely to be the first one a company reaches for. 

The EA expects around 60% of the projected public supply deficit to be met by reducing leaks, with new supply (reservoirs, recycling, transfers and desalination) filling the rest. 

So how do these alternatives stack up? 

• Leakage causes a loss of nearly 3 billion litres a day. Of this, Thames Water's system loses about 570 Ml/d — a fifth of the total leak. Leakage reduction is the obvious first move companies can make. Ofwat's price review allocated £700 million for this purpose, targeting a 17% reduction in leakage by 2030 and 50% by 2050. Naturally, there's a hard ceiling on how much additional water can be recovered. More supply will still be needed. 
• Water recycling requires less energy than desalination — around 0.11 kWh per cubic metre — due to lower salt content. The resulting sludge is also less toxic and can be used in agriculture. However, municipal wastewater is limited, and many consumers find the "toilet-to-tap" source unappealing. In practice, the two methods are often combined: desalination to ensure a baseline supply and recycling to stretch it.
• New reservoirs need large expanses of often prime agricultural land, followed by a pricy civils programme. But they last a century or more with minimal structural maintenance. On the contrary, desalination membranes must be replaced every 5 to 7 years, and plants rarely last longer than 30 years. Over their lifetime, reservoirs are the cheaper option.
• Water transfers move supply from wetter to drier regions. An example is the Severn to Thames Transfer, a scheme to move up to 500 Ml/d from the Severn at Deerhurst to the Thames at Culham. The method is energy-cheap compared with unsalting seawater. But it introduces no new water into the system, and the donor region needs a surplus. The spread of invasive species is an additional risk. 

Ultimately, despite its drawbacks, desalination is the one source that's independent of rainfall. 

It "will not be the solution everywhere," Robertson says. "But it has an important role alongside demand management, leakage reduction, water reuse, reservoir development and water transfers. The future of water security will depend on combining multiple solutions rather than relying on a single source."

What Does This Mean for the Water Sector? 

For water companies

In practice, desalination is being planned where alternatives are limited — on islands with no other source, or as a drought standby for when rivers and reservoirs fall short. The EA says that it is "particularly relevant where other options are limited, and locations are suitable."

But the process remains slow, expensive and, as St Austell's history shows, risky.

For water companies, the question is one of fit: Do their geography, the size of the supply gap and available cheaper options offset the risks of desalination?

For environmental consultancies and engineers

It's early days when it comes to winning actual work for creating a desalination scheme: Most UK facilities won't break ground until the 2030s. But water companies will need help with feasibility studies, brine disposal plans and environmental impact assessments. Experts in permitting and marine impact will go to the front of the queue. 

For regulators and Ofwat

It's all change for regulators as they are to be merged into one entity, responsible for balancing supply with environmental concerns. In its White Paper, the government has promised "greater stability, transparency, and an integrated view of both economic and environmental performance," and the new regulator must allow for delivery while maintaining safety for people and the natural world.

Officially, the door is open, but enthusiasm is measured. The government notably doesn't mention desalination by name in its White Paper.

The EA does have a dedicated position on desalination, but views it only as part of a "diverse range of supply and demand options to secure resilient water supplies for the future."

For local authorities and coastal communities

Local authorities decide most desalination applications. That puts them between water companies that need the supply and residents who are sceptical, sometimes hostile, and yet live in a water-stressed region. Discharge, extra traffic and construction are all sources of local objection. Timely engagement and consultation are required to get desalination schemes approved.

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What the Water Sector Is Watching in 2026 

Several fast-moving developments will shape desalination's future in the UK and dominate conversations at events like WWEM 2026.

• The RAPID gated process. Any major desalination scheme must undergo RAPID's staged assessment, now folded into Ofwat's new Major Water Infrastructure Programme (MWIP). Funding is released gate by gate, and each gate requires detailed technical and environmental evidence. Water companies will benefit from understanding the process early and bringing in consultants who know how to navigate it. 
• White Horse Reservoir (formerly SESRO) is a proposed 670-hectare water storage facility in Oxfordshire. Intended to supply 271 million litres of water a day to 15 million people, it's the flagship for the "reservoirs-first" strategy and the main alternative to new desalination in the water-stressed South East. RAPID launched a funding consultation in late 2025; if planning succeeds, construction could begin in 2029. The speed of progress will shape how much desalination the area might need. 
• Ofwat's AMP8 investment cycle (2025–2030). Within the current price review, RAPID's 28 strategic schemes — some £2 billion of development funding to unlock around £50 billion of infrastructure — include reservoirs, water transfers, recycling and desalination.  When completed, the pipeline will deliver 999 Ml/d, a fifth of the projected 2055 shortfall. This is where desalination projects compete with other methods for funding and approval. 
• Brine discharge regulation. Here's where desalination's environmental case could be won or lost. The EA will only permit discharges that 'protect and enhance' the receiving waters, requiring an environmental impact assessment that models how the hypersaline brine mixes and disperses at the outfall. So getting brine management right is a significant practical challenge the sector faces. 

Join the conversation at WWEM 2026, part of the ESS Expo, where water companies, consultants and regulators weighing desalination against the alternatives meet. Register for free today.

FAQs: Desalination in the UK

Why doesn't the UK use desalination more? 

The method is expensive, energy-intensive and slow to get permits for. The wet climate means the UK has many other options. But climate pressure, rising demand and tightening abstraction rules are making desalination viable, and maybe even necessary. 

Does desalination use a lot of energy? 

Reverse osmosis, the favoured process for desalination, requires about 3.65 kWh of energy per cubic metre. Estimates vary, but it consumes much more energy than treating river or groundwater. 

How much does a desalination plant cost? 

Desalination plants are expensive. Thames Water's Beckton plant has cost around £518 million in total to produce only seven days' worth of water. Anglian Water has budgeted £1.7 billion for three more plants. 

Author bio: Michael Willoughby is a British content writer and journalist based in Kosovo. He has more than 20 years' experience in B2B communications, starting out as a dot-com PR practitioner in New York City. He later retrained as a journalist and became a staff writer on OnOffice and Building magazines, covering sustainability, construction, architecture, engineering and the built environment. He was communications manager for Willmott Dixon's Re-Thinking (sustainability) department.

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