What will UK drinking water treatment look like in 2050?

This opinion piece first appeared in The Water Report in August 2026.

The need for change

The central challenge is not that UK drinking water is currently of poor quality. In fact, regulatory compliance remains extremely high in comparison with other countries. Instead, the problem is that drinking water quality must be maintained and improved while raw-water quality deteriorates, assets age, carbon budgets tighten and supply–demand deficits widen. And all this must be achieved against the backdrop of low public confidence in the water industry.

Today, the combined population of the UK is 70 million people. By 2050 this is expected to rise to 72.5 million, with much of this growth coming from south-east England. This is already the most water-stressed area of the country, meaning it will face the most acute challenges in providing sufficient potable water for a growing population. Over the same time period, projections indicate we will see hotter, drier summers and warmer, wetter winters. During summer, we are likely to see heatwaves exceeding 40°C, droughts and superstorms.

So what will UK drinking water treatment look like in 2050? While no one can fully predict the future, it is informative, and fun, to attempt to answer this question! No single solution will cover the whole breadth of challenges across the UK. By 2050, the water industry will be designing, building and operating low-carbon and high-assurance drinking water treatment plants that effectively treat diverse and challenging source waters. Digital technologies will help make water treatment more efficient, such as through AI-assisted automated process control and predictive maintenance. The journey to 2050 is also predicted to involve the following.

Desalination

In the south and east of England in particular, there is a need for alternative sources to supplement, rather than replace, existing water supplies. This is reflected in a position statement by the Environment Agency published last autumn, explaining that desalination of seawater or estuarine water is likely to be needed to ensure future water security. Anglian Water is currently in the early stages of planning two new desalination plants, in Norfolk and Lincolnshire, which are scheduled to become operational by 2040. The Regulators’ Alliance for Progressing Infrastructure Development (RAPID) has been created to accelerate the development of major new water infrastructure projects such as these.

In this context, it is worth mentioning a couple of existing UK desalination schemes. The first being Thames Water’s Thames Gateway desalination plant, currently the only municipal drinking water desalination plant in mainland England. This plant is designed to treat brackish water (a mix of seawater and Thames river water). It was built in 2010 to secure water supplies to London during droughts. It has only operated on a few occasions since, always at well below its design capacity of 100 ML/d. Meanwhile, on the Isles of Scilly, a desalination plant has been operational since 1992 and its output is blended with groundwater supplies. Demand for water is highest during the summer tourist season, when desalination provides up to ~40% of the public water supply.

Changing public perception towards alternative water sources

Alongside new desalination schemes, there will be calls to explore other alternative drinking water sources, such as direct or indirect recycling of municipal wastewater.

International examples already demonstrate what such schemes can look like. At the Terminal Island Advanced Water Purification Facility in California, multiple treatment barriers, including microfiltration, reverse osmosis and advanced oxidation, are used to produce high-quality recycled water. This is supplied to local industrial users and is used for irrigation and to replenish surface and groundwater supplies. While projects of this nature were once considered unconventional, they are increasingly viewed as practical solutions to long-term water security challenges and indicate how UK drinking water treatment may evolve in the coming decades.

Although projects of this type come with many technical challenges, perhaps their biggest obstacles are public perception and acceptability – often fuelled by phrases such as ‘toilet to tap’ and ‘yuck factor’. Again though, there are international success stories that could alleviate the concerns the UK water industry will face when it journeys down this path. For instance, the Orange County Groundwater Replenishment System in California demonstrates that significant increases in public support for wastewater recycling schemes are achievable, in this case from 40–50% to 70–80%, but only after over a decade of sustained public engagement before, during and after construction. Independent scientific experts were used as trusted communicators and the treatment plant now attracts over 20,000 visitors annually, serving as a popular community educational facility.

Catchment management partnerships

Preventing pollution from entering rivers, reservoirs and aquifers in the first place will perhaps grow in importance over the coming decades. A flagship example of what can be achieved when water companies partner with landowners and regulatory bodies is the case of metaldehyde, a pesticide used to control slugs, which is resistant to conventional water treatment processes. In 2015, Anglian Water began its “Slug it Out” catchment trial, during which it worked closely with local farmers, incentivising them to use an alternative pesticide, ferric phosphate, in place of metaldehyde. The success of this scheme in reducing metaldehyde concentrations in drinking water, combined with the lower cost of catchment management against upgrading treatment plants for metaldehyde removal, eventually led to the outdoor use of metaldehyde being banned by the UK government in 2022.

Now the UK water industry is in the early stages of exploring catchment management as a mechanism for reducing concentrations of PFAS in drinking water. There is a lot to learn in this area, but its feasibility may prove to be catchment-specific – working best in locations where there is a limited number of well-defined point sources of PFAS. Jersey is an example, with well-publicised PFAS pollution on the island attributable to the use of firefighting foams at Jersey Airport in the 1990s. Owing to the extremely high environmental persistence of PFAS, private boreholes and wells in the vicinity still contain low levels of the chemicals.

Innovative treatment methods

By 2050, treatment plants may look very different from those operating today. Rather than relying on a small number of conventional processes, notably coagulation–flocculation–sedimentation followed by granular filtration and chlorination, utilities are likely to adopt multiple treatment barriers capable of treating variable and challenging source waters.

The Mayflower Water Treatment Works, which entered service in 2020 and supplies water to ~250,000 people across Plymouth, is an example. It is based on suspended ion exchange – inline coagulation – ceramic microfiltration – granular activated carbon – ultraviolet disinfection and chlorination.

The benefits of ceramic microfiltration and ultrafiltration membranes, typically as replacements for media filtration, are becoming increasingly clear in such situations. These can include the capability to treat variable quality raw waters, durability, low irreversible fouling and lower whole life costs compared with established polymeric membranes. Conversely, they do have higher capital costs than polymeric membranes. The application of ceramic membranes is already widespread in Scotland, especially at small, remote treatment plants, such as on Shetland, and for treating peaty upland waters. Earlier this year, Scottish Water awarded an £800 million framework contract for the design, construction, commissioning and handover of ceramic membrane water treatment plants throughout Scotland up to 2033.

Looking forward to 2050, there is keen interest in seeing whether current pilot trials involving ceramic nanofiltration membranes are successfully translated into full-scale operation. If they are, then there are many potential applications within drinking water treatment, such as for removal of PFAS and other micropollutants and controlling disinfection byproducts.

Alternative treatment options for PFAS include activated carbon adsorption and ion exchange resins. However, in a world where money is finite and has many competing demands upon it, the cost of upgrading treatment plants needs strong justification – and typically, regulatory support.

Conventional granular activated carbon is currently the benchmark for PFAS removal in drinking water treatment. It is effective for removing longer-chain PFAS, those with over six carbons, and evidence suggests that thermal reactivation at high temperatures, a standard part of operation, destroys PFAS compounds. Work continues to develop surface-modified activated carbons, which provide improved removal of short-chain PFAS.

Ion exchange resins and tight membranes (nanofiltration or reverse osmosis) can offer superior performance for PFAS removal, especially the problematic short-chain compounds, but both generate waste streams in which removed PFAS accumulate, leading to the common question of how to efficiently remove or destroy PFAS to avoid its release back into the environment. Combining a step to concentrate PFAS in waste streams, typically foam fractionation, with chemical degradation, such as an electrochemical process, hydrothermal alkaline treatment (HALT) or supercritical water oxidation (SCWO), has shown promise in research studies, though this is still some way off being deployed in full-scale water treatment.

Decentralised treatment

Today, someone designing a water treatment and supply system from scratch may favour a decentralised model, where water is sourced, treated and reused on a local level. Rather than installing and maintaining long distances of underground pipelines, decentralised water treatment has the advantage of being more sustainable, in terms of lower initial investment, facilitating water reuse and conservation and reducing pumping costs. Disadvantages include a higher operational and maintenance burden (and who is responsible for this?) plus developing a suitable regulatory framework.

Many existing examples come from low-income countries or remote regions and involve renewable energy, nature-based treatment, membrane filtration and remote monitoring. In a UK context, while there is little indication we are moving away from our existing centralised model, it is easier to foresee a role for mobile treatment units, to provide drinking water during emergency outages of public water supply, for instance, and to target pollution hotspots, such as nitrate-contaminated groundwater or point sources of PFAS, e.g., brownfield sites and airfields. Integrating decentralised treatment units with existing water/wastewater networks will widen potential applications.

Closing thoughts

The themes above give a flavour of how UK drinking water treatment will adapt to changing regulatory, environmental and demographic pressures over the coming decades. One final prediction is that anyone looking back at this article in 2050 will see there were some challenges and solutions that were not readily apparent to the authors in 2026.