Increased public awareness of micropollutants and emerging contaminants in wastewater and drinking water, along with tougher scrutiny from regulators, means the water sector needs a more cohesive response, argues Lila Thompson, chief executive, British Water.
Finding consensus on how micropollutants and emerging contaminants are defined, how UK policy needs to evolve, and the barriers to current treatment options, will be crucial for the UK water sector over the next five years.
In common with much of the world, many micropollutants and emerging contaminants are not yet regulated in either treated wastewater effluent discharged to the environment, or drinking water. This means there is no regulatory incentive for water companies to adopt the advanced removal technologies that are already available in the market.
In March 2025, the Drinking Water Inspectorate (DWI) published updated guidance for PFAS (per- and polyfluoroalkyl substances) in drinking water. The document requires water companies in England and Wales to monitor for a wider range of substances and update their risk assessments accordingly. The guidance follows a guideline of 0.1 micrograms per litre for some 48 named PFAS, which is equivalent to 0.1 parts per billion.
In a comprehensive article on its website, the DWI explains that “there are currently no statutory standards for PFAS in drinking water England and Wales, nor is there a World Health Organisation (WHO) guideline value. The DWI has taken a precautionary approach and produced tiered guideline values for water companies to adhere to.”
The regulator says that it is “working closely with the UK Health Security Agency, the Environment Agency, and government to adopt the most up to date information regarding standards and toxicology.” On the policy front, there are also measures in the Environment Act 2021, which mandates increased monitoring of water quality, including for emerging contaminants.
Supply chain companies such as British Water members Adler & Allan, and sister company Detectronic, that specialise in wastewater monitoring technologies, have highlighted the challenges ahead.
Dave Walker, global future trends director at Detectronic, said, “Supply chain companies are on the front foot in developing new technologies and products to meet water company demands, and this is no less the case with monitoring and analysis of micropollutants and emerging contaminants.
“There is a data and long-term knowledge gap here, and any technologies installed at wastewater treatment plants need to be assessed and tested extensively in the field before scaling can begin. However, without regulatory compliance driving and/or justifying water company operational expenditure, real progress on this growing threat cannot be achieved.”
In the absence of clear and unified national legislation on micropollutants and emerging contaminants, European and international standards continue to be influential in water company decision-making.
These include the EU Water Framework Directive, which has a watchlist of priority contaminants, and the revised EU Urban Wastewater Treatment Directive which entered into force on January 1, 2025. The revision aims to improve water quality, protect human health, and promote circularity through stricter treatment standards and extended coverage to include new pollutants micropollutants and incorporates a system of producer responsibility for pharmaceutical and cosmetic producers to help cover costs of advanced wastewater treatment, particularly for removing micropollutants.
Water companies are also guided by the WHO and the Organisation for Economic Co-operation & Development, that both acknowledge the challenges posed by micropollutants and emerging contaminants in water sources. Both organisations also advocate for comprehensive research, international cooperation, and the development of effective policies and technologies to manage public health and the environmental risk.
Definitions and pathways
Micropollutants are organic and inorganic substances found in trace amounts (ng/L to µg/L) that are biologically or ecologically active. Emerging contaminants can be defined as chemicals not yet widely regulated or studied but increasingly detected. Examples include household and industrial chemicals containing PFAS or PFOAS, pesticides and herbicides, pharmaceuticals, nanomaterials, microplastics, and personal care products such as suncreams and cosmetics.
These substances are ubiquitous to modern life and while on a microscale they do not pose a threat, if left untreated or to accumulate over the long term, can lead to issues such as bioaccumulation, endocrine disruption, antimicrobial resistance, and ecosystem damage.
There are many ways micropollutants and emerging contaminants enter wastewater systems and the aquatic environment – through domestic sewage, healthcare and industry discharge, agricultural runoff and during stormwater or combined sewer overflow events.
The fourth British Water micropollutants conference took place in Leeds on 28 May 2025, and I heard about the many treatment and monitoring options already in use and available to the water sector. I also learned more about upstream initiatives that mitigate the environmental risks and challenges associated with micropollutant emissions, along with the research and development that is underway in this space.
Treatment barriers
Treatment capabilities range from conventional processes designed for nutrients, such as phosphorus, nitrates, and pathogens, to advanced technologies such as activated carbon absorption, ozonation, membrane filtration and reverse osmosis or oxidation processes. While these advanced technologies are showing promise in removing micropollutants and emerging contaminants from wastewater, several barriers to adoption are slowing or limiting widespread implementation in the UK.
These include:
Cost and resource intensity: Advanced treatment technologies require significant infrastructure investment that many wastewater treatment plants (WwTPs), especially in smaller or rural locations, cannot justify without regulatory pressure or clear cost/benefit certainty. Advanced technologies often demand more energy and maintenance than conventional treatment methods. However, with the doubling of investment in the water sector in AMP8 – the 2025-30 investment period, these barriers could well be overcome.
Technical process complexity and scaling: Retrofitting existing WwTPs with new technologies can be logistically complex, especially for plants with space or hydraulic constraints. The optimal technology varies widely depending on size, location, and influent characteristics of a WwTP – making scaling for universal adoption harder.
Additionally, the effectiveness of technologies can vary depending on the water chemistry and contaminants present and carry the risk of generating byproducts that may themselves be harmful if robust pilots or trials are not undertaken.
Monitoring and detection limitations: Many micropollutants and emerging contaminants originate upstream, so end-of-pipe solutions alone are insufficient. Monitoring and implementing advanced technologies also require trained personnel which can be beyond the capacity of some companies.
With this, limited long-term environmental and health data either available to water companies or gathered directly can hinder risk-based prioritisation of what to treat and how. These limitations also tie into the skills gap and shortage that the sector is seeing.
Public and political awareness: Because micropollutants and emerging contaminants are invisible and do not cause immediate health crises, public and political pressure for reform has been low, historically, compared to leakage and combined sewer overflows. Of course, this is no excuse not to address the challenge, but does give the industry an opportunity to get ahead of the narrative and set out clear funding and strategic priority mandates.
Future policy development
Water companies are at a crossroads when it comes to tackling micropollutants and emerging contaminants and meanwhile, public pressure is gathering pace. Advanced technologies do exist to detect and mitigate risks, but policy is still catching up and considerable investment will be required.
Given current discussions, it can be expected that lobbying on legal limits for micropollutants and emerging contaminants, from the sector and environmental NGOs, will continue, and legislation and regulation will follow. Investment in solutions and upstream interventions might be hard for water companies to justify, at a time of stretched budgets, without clear legislative signals.
This impasse creates a case for more research and knowledge-building, stronger monitoring and data analysis, clearer risk-based regulations, more cross-sector collaboration, along with an effective public education and communications strategy – all of which are challenges the sector can rise to.
All are essential to mitigate not only the growing threat micropollutants and emerging contaminants pose, but also, media headlines that misinform the public, erode trust, and impact on the water sector’s reputation.
