UK maps route to reducing chemicals in the environment

The latest data from the UK water industry’s most ambitious chemical monitoring programme suggests targeted policy, collaborative science, and source control can successfully tackle forever chemicals. 

UK Water Industry Research (UKWIR)’s Chemical Investigations Programme (CIP) represents the UK water industry’s most comprehensive scientific response to tackling chemical substances in the water environment.

Through consistent monitoring, shared methods, and collaborative working, the programme is supporting greater transparency and earlier, better-informed action. It is a prime example of the system-wide, joined-up approach called for in the Government’s recent white paperon water sector reform.

Findings from the CIP3 Trend Monitoring Project (2020-2025) showed downward trends in concentrations for all but one ofthe chemicals monitored including perfluorooctane sulfonate (PFOS) and lead. The report provides definitive evidence that national and international source control measures, such as product bans and phase-outs, alongside upgrades to the treatment process, are successfully reducing hazardous substances in water systems. 

By strengthening the evidence base on chemicals and helpingto pin point the factors driving impacts in different places, CIP supports the white paper’s call for more targeted interventions, clearer prioritisation, and sustained progress towards cleaner rivers and seas. In addition, by evidencing effective source control and targeted measures, CIP helps focus investment where it delivers the greatest benefit, supporting better value for water company customers. 

“The water industry isn't the source of these chemicals, and our data shows that when there is rigorous source control, the environment heals without the need for carbon-heavy, expensive interventions from utilities,” explains Jenni Hughes, strategic programme manager, UKWIR. “This evidence-based approach is providing a blueprint for how the UK can tackle emerging compounds without defaulting to end-of-pipe solutions that would cost bill-payers significant sums.” 

Trend monitoring  

The recent Trend Monitoring Project, which collectedfour-and-a-half years of data across England and Wales, is the proof thatbanning harmful substances at manufacturer level works. Launched as apartnership between water companies and regulators - including theEnvironment Agency, Defra and Natural ResourceWales - in 2010, the CIP is currently in its fourth phase(CIP4).  

“You can’t control what you don’t measure,” says Mark Craig, Severn Trent Water’s long term asset strategy lead andUKWIR co-lead for wastewater. “With this trend monitoring, wehave the power to show what is actually happening in our environment.” 

“It proves that for many substances, if the source controlmeasures are in place and working as they should, concentrations in sewageeffluent decline significantly.”  

Analysis of monitoring data from 2020–25 showssignificant downward trends for 19 of the 20 substances of high regulatory concern, including: 

Tributyltin (TBT): Historically usedas a highly effective biocidal antifouling paint on ships hulls, TBT is apotent endocrine disruptor in marine life. Following a global ban in 2008,environmental levels have plummeted. This approach remains a goldstandard in environmental policy, proving that strictly enforced internationalbans can successfully mitigate legacy pollutants. 

PFOS: Part of the per-and polyfluoroalkyl substances(PFAS) family of highly persistent ’forever chemicals’, PFOS was primarily used as a stain repellent intextiles and firefighting foam. While data from UK water monitoring sites,such as those owned and operated by SevernTrent Water, show significantly declining concentrations ineffluent, they still exceed the EU’s Environmental QualityStandards (EQS) in some rivers. PFOS remains achallenge due to its extreme persistence and tendency to leach from sourcessuch as historical landfill sites into groundwater.  

The only exception to the downward trend for chemical concentrations in the substances investigated was for dissolved mercury, which the CIP3 Trend Monitoring Project shows has had an increasing presence in the environment over time. Mercury enters the environment through a combination of geological and industrial processes such as mining, fossil fuel combustion, and waste incineration. 

Crucially, the report identifies substanceslikely to cause future failures of the EU’s Environmental Quality Standards(EQS), allowing companies to prioritise catchments for investigative orremedial action. 

Scientific safety net 

As UKWIR moves through CIP4 from 2025-30, andCIP5 from 2030-35, the framework is designed to be agile, with different chemicals coming under investigation as deemed necessary, based on the scientific and environmental evidence. 

“We work collaboratively with the Environment Agency to write the scope and will continue to do so over the coming stages of the programme,” says Mark Craig. “We bring chemicals onto the list and take them off once we’re satisfied, they no longer pose a risk. It’s a programme that’s designed to be flexible and futureproof.” 

By focusing on keeping chemicals out of the sewer system in the first place, UKWIR is committed to ensuring that the path to a cleaner environment is both scientifically sound, environmentally sensitive, and economically responsible. 

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