With the need to find more water resources and improve wastewater treatment to strengthen the resilience of the UK’s water and wastewater infrastructure firmly at the top of the water sector agenda, quaternary treatment looks set to play a key role in the toolkit.

Dale Foster and Adrian Heneghan from HUBER Technology UK discuss why the UK water companies are looking towards technologies which are already available, widely in use in Europe and have proved their worth.

Dale Foster and Adrian Heneghan: The UK water sector is of course accustomed to getting to grips with multiple challenges in pursuit of its primary goals of providing a consistent and reliable supply of high quality drinking water and the safe disposal of wastewater products.

However, it’s true to say that over the last decade these have been exacerbated by the growing impacts of population growth, changing water use, competing demands for ever-greater water supplies from the domestic market, agriculture and industry, climate change and significant environmental pollution.

To respond to these challenges the UK water companies are using a combination of both proven solutions and new approaches.

Photo: HUBER tank mounted Pile Cloth Filter RotaFilt® trial unit

Here in the UK tertiary treatment is generally the primary process - from our side, we think this is set to change.

Bringing quaternary treatment technologies to the table offers the UK water companies a unique opportunity to tackle two key issues which are firmly at the top of the boardroom agenda – the pressing need to find new water resources and limiting the presence of Perfluoroalkyl and Polyfluoroalkyl Substances – generally known as PFAS or “forever chemicals” - in the water environment.

The UK water companies are now turning their attention to these technologies which are already widely used in Europe. HUBER Technology already has a strong track record with numerous reference sites already in place across Europe and globally. 

We are now seeing an uptick in interest and are currently in discussion with one of the water companies about how quaternary treatment can help to strengthen their water resource availability in drought conditions.

Water resources under growing pressure

Starting with water resources, quaternary treatment technologies have considerable potential to play an important role in helping to meet ever-growing demand. Last year the Environment Agency warned that England faces a massive 5 billion litre a day shortfall for public water supplies by 2055 without urgent action to futureproof available resources. An assessment which does not take into account new emerging demands, such as data centres and hydrogen production.

The impacts of prolonged drought have also undoubtedly concentrated the minds of the water sector - 2025 was the hottest and sunniest summer on record: 1.69°C above the long-term average.

All water companies, except Portsmouth Water activated their drought plans in 2025 and were granted 46 drought permits and 2 drought orders. A series of heatwaves also meant high demand for water over July and August - 15 key reservoirs were below 50% full at the end of September 2025.

In October 2025 the Environment Agency published a policy paper setting out its position on water recycling as a public water supply option in England, saying it believes that water recycling schemes should play a larger role in future national water supplies.

According to the Agency, the Langford indirect water recycling scheme operated by Essex and Suffolk Water which opened in 2002, is currently the only operational water recycling facility in England. The scheme uses wastewater discharged to the River Chelmer that would have previously been discharged into the sea. The treated water is then abstracted downstream and further treated for potable water supply. The scheme primarily operates during low flow periods when it can provide up to 70% of the River Chelmer’s flow.

Water reuse with final effluent polished to a very high standard using quaternary treatment introduced into the public water supply via rivers or reservoirs already has significant traction in Europe – wider uptake in the UK could play an invaluable role in the water companies’ toolkit to ensure water resource resilience in their water supply systems.

The same approach could also be considered for a number of the major Strategic Resource Options projects in the RAPID programme where quaternary treatment could have a key role to play in getting these new water resources up to potable water standards into the systems and networks. There are now 28 major new infrastructure schemes in the programme, including 9 new reservoirs, 12 water-recycling plants and long-distance transfers - and the water companies developing these water resource solutions are already putting the building blocks to design the SROs.

Environment Agency: “Water recycling is successfully implemented worldwide, showing its viability as a water supply solution”

The Environment Agency’s policy paper states:

“Water recycling is needed to meet the mounting challenges facing our national water resources. The impacts of climate change, population growth and the need to increase resilience to drought mean that action is needed now. ...

“We believe water recycling can play an effective and increasingly important role in securing water supplies. It enables water companies to maximise their available resources.

“Water recycling is successfully implemented worldwide, showing its viability as a water supply solution.”

Further down the line – quaternary treatment needed to tackle tighter regulation of PFAS

Looking further down the line, we think the UK water companies will also be looking to quaternary treatment technologies to address the growing problem of PFAS which, as with CSO spills, has risen up the public and regulatory agenda and is a fast-moving area of concern.

Despite the fact that in this instance the water companies themselves have not caused the problem, they are being tasked with addressing the problems. In the face of increasing public pressure and media coverage, future legislation is undoubtedly coming down the line to address two key issues:

• the historical/ legacy widespread presence of PFAS in the environment which has built up over decades
• ongoing use of PFAS in a wide range of everyday products – including firefighting foam, pharmaceuticals, cosmetics

At the start of February, the Government launched the UK’s first-ever plan to tackle 'forever chemicals' and risks posed by PFAS. Under the Plan a consultation will be launched later this year on introducing a statutory limit for PFAS in England’s public supply regulations. Currently, there are no standards in the Regulations for PFAS in drinking water in England and Wales.

Separately, the House of Commons Environmental Audit Committee is currently progressing with work on its ongoing inquiry launched last year - Addressing the risks from Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS). MPs on the cross-party committee have been exploring how the government should approach regulating and remediating PFAS.

In March 2025, the Drinking Water Inspectorate issued revised and updated guidance on the Water Supply (Water Quality) Regulations 2016 (as amended) for England and Water Supply (Water Quality) Regulations 2018 for Wales specific to PFAS (per- and polyfluoroalkyl substances) in drinking water.

The Inspectorate expects companies to develop robust strategies for dealing with PFAS which must be considered as ‘live’ documents that should be adaptable and able to respond to potential future changes in regulatory expectations.

The Guidance says that to comply with the latest DWI requirements, investment is needed to install specific treatment processes to enable the removal of PFAS to below DWI thresholds at water treatment works.

“We expect companies to extend their existing risk-based strategic approaches to resolve and mitigate risk at these sites in a systematic way that deals with the highest risk sites as a priority. Such a risk reduction strategy should aim to progressively reduce PFAS concentrations in drinking water.”

Tighter regulation already in force in Europe – will UK follow suit?

In terms of tighter regulation, Europe is already ahead of the UK on this issue – the revised Urban Wastewater Treatment Directive (UWWTD) which entered into force in January 2025 introduced stricter treatment and monitoring requirements for wastewater, including an obligation to remove at least 80% of certain micropollutants using advanced broad-spectrum treatment processes during quaternary treatment.

Quaternary treatment will have to be fully implemented in the EU by 2045, with intermediate deadlines.

The Directive applies to large wastewater treatment plants responsible for handling a pollution load of at least 150,000 p.e. (population equivalents). All discharges from these plants must meet the criteria for micropollutant removal by the end of 2045, with interim requirements for 20% of plants to comply by 2033 and 60% by 2039.

Smaller plants (10,000 p.e. and above) must also meet quaternary treatment requirements by 2045 if they discharge water into areas where the accumulation of micropollutants poses risks to human health or the environment.

The recast UWWTD also strengthens the polluter pays principle and requires the removal of micropollutants from urban wastewater. To cover at least 80% of the costs, it mandates extended producer responsibility (EPR) schemes with two industrial sectors, pharmaceuticals and cosmetics, identified as main polluters.

Getting ahead of the game

Despite the raised level of concerns about PFAS and the need to tackle the issue, it remains to be seen how swiftly the Government will move to bring more rigorous legislation into effect. In the meantime, the water companies nevertheless have a great opportunity to get ahead of the curve and adopt a proactive approach to the problem by bringing in more advanced quaternary technologies which are already available.

Giving evidence to the House of Commons Environmental Audit Committee’s PFAS inquiry on Dr Richard Daniels, Director, Chemicals Regulation Division, Health and Safety Executive on 4 February, he told the Committee

“It helps to have that starting point to see what is being done and perhaps some of the challenges that the EU has faced. It is very much about that front-end technical analysis, which we might be able to speed up using what the EU, for example, as a trusted jurisdiction has done, and then look at what that means in practice for the UK. The thing is, why would we as a regulator ignore what other people have done where it is based on good science and evidence?

Later this year we will be holding a free-to-attend webinar providing a detailed overview of HUBER’s range of tried and tested solutions and how they can help water companies to tackle the challenge of PFAS in their own operations. Please email This e-mail address is being protected from spambots. You need JavaScript enabled to view it to register your interest in attending and we will notify you in due course of the event date.

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