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A year-long analysis of England’s wastewater shows how recreational drug use spiked with major sporting and music events, heatwaves and bank holidays, with widespread drops in usage linked to major drug seizures by police.

The work, led by a team at ÌìÃÀ´«Ã½’s School of Public Health, is believed to be one of the most detailed studies of its kind to measure drug consumption in a single country, and involved researchers analysing more than 1,700 water samples from 15 wastewater treatment sites across England over the course of a year (2022).[1]

By searching for known chemical signatures for several drugs, including cocaine, heroin, ketamine, amphetamine and MDMA, the team was able to use samples from wastewater treatment plants to piece together a detailed picture of drug use in England over time.

Their findings show that during 2022, drug use in England was widespread. There were spikes in recreational use of some substances aligned with England’s FIFA World Cup games, summer heatwaves, music events and bank holidays – including the Queen’s Jubilee celebrations.  

Water samples were tested for known chemical signatures for 20 substances to piece together a detailed picture of drug use in England over time. Samples were analysed by liquid chromatography-mass spectrometry. (Credit: Imperial College London / Jo Mieszkowski)

The researchers say the work highlights how wastewater surveillance can be used to monitor changing patterns in national drug consumption and the impacts of major public events and interventions. Beyond consumption trends, they believe the approach could be used to better understand the established links between drug-related overdose deaths and seasonal weather changes.

, from the Environmental Research Group at ÌìÃÀ´«Ã½, and principal investigator of the study, said: “On the surface, our work provides detailed insights into the links between recreational drug use and major public events and celebrations over a year. But this type of wastewater surveillance work is also valuable for public health, not least in being able to quantify usage in near real time within and across communities.

“Each year, the UK is seeing increases in drug‑related deaths and in the number of people using drugs frequently. These patterns have serious consequences for health, crime and society as a whole. By measuring the substances that ultimately end up in wastewater, we can make more informed decisions in near real time on how, where and when to implement harm reduction initiatives as well as direct and measure the impact of law enforcement efforts.”

Professor Leon Barron and team analyse wastewater samples in the lab at Imperial's White City Deep Tech campus. (Credit: Imperial College London / Jo Mieszkowski)

In the , researchers looked for traces of 20 chemical signatures used to identify illicit substances, as the compounds are broken down by the body, excreted and passed into the sewage system. These included primary drug compounds themselves, metabolites from their breakdown in the body, and substances commonly cut with the drugs.[2]

They found that on average, cocaine was detected at the highest average daily levels, followed by heroin, ketamine, amphetamine, MDMA, and methamphetamine.

By measuring the substances that ultimately end up in wastewater, we can make more informed decisions in near real time on how, where and when to implement harm reduction initiatives as well as direct and measure the impact of law enforcement efforts. Professor Leon Barron School of Public Health

Comparing the samples with European drug surveillance data, the analysis showed that ketamine use in particular was higher in several English sites studied than any other European site monitored during the same period.

However, the researchers caution against their data being used to produce estimates for national average consumption, as the sample sites were mostly classified as urban areas and not representative of the entire population.

Unlike other major wastewater studies, which have only been able to show a short-term snapshot of UK drug use, the work from the Imperial-led team provides a dynamic picture of how drug use changed over the course of the year and for some sites, almost every day.

They found that consumption fluctuated by day of the week across all sites, with a clear trend in recreational use at weekends for cocaine and MDMA, with markers peaking in water samples on Sundays. Traces of other drugs, such as heroin, remained steadier across the week.

Drug use (specifically cocaine, MDMA and ketamine) also spiked in line with public holidays and major events in 2022. For example, cocaine and MDMA spiked in line with Bank Holidays (including the Queen’s Jubilee celebrations in June), cocaine use spiked in line with England’s World Cup football matches (in November and December), and traces of cocaine, MDMA, methamphetamine and ketamine all spiked around the Eurovision Song Contest.

There were also strong correlations between the presence of some substances, indicating drugs frequently being used together – specifically cocaine and ketamine, but also cocaine and alcohol.

The analysis also showed trends coinciding with major law enforcement operations – including a widespread drop in cocaine usage in March following a of the drug in Southampton.

Professor Barron added: “The impact of drug seizures on cocaine consumption in major urban areas was a new and very valuable benefit of wastewater analysis. We were also able to detect which drugs people replaced cocaine as supply was potentially affected, and also how long it took for the illicit market to recover. It was clear that these tonne-sized seizures could have impacted cities that were hundreds of miles apart.”

This study was conducted over a 12-month period in 2022 with researchers collecting 24-hour composite wastewater samples at 15 wastewater treatment plants in England – locations are not identified due to confidentiality agreements. The catchment population areas for plants ranged from 100,000 to more than 1 million people. Together, the sampled treatment plants covered 21% of the national population. Of the 20 substances screened for, two (both nitazene-type synthetic opioids) were not detected in samples.

The latest findings follow , conducted in 2025, which showed traces of illicit drugs were common in wastewater across the EU and associated countries. The European study also found that two sites in England – one of which was tested by the Imperial team – had among the highest levels for cocaine and ketamine consumption of all countries sampled.

Professor Barron, explained: “It is important to understand in more detail why we are seeing UK drug use rise to this level for cocaine and ketamine, compared to the rest of sites studied. It indicates there’s a serious and worsening problem here that needs to be addressed urgently. 

“When people take drugs, the substances are broken down in the body before being discharged into the wastewater network, but they leave an identifiable chemical signature. Our laboratory tests, which have been independently verified, analyse wastewater samples to detect these chemical signatures which can then be used to monitor near real-time trends in drug use, as well as observing whether interventions are having any impact.”

The Imperial-led research, published in the journal Addiction, was supported by the Home Office, the Defence Science and Technology Laboratory and the National Crime Agency, and was commissioned via Imperial Projects (IPROJ). Professor Barron was part-funded by the National Institute for Health and Care Research (NIHR) under the Health Protection Research Units in Environmental Exposures and Health, and Chemical and Radiation Threats and Hazards, both partnerships between the UK Health Security Agency and ÌìÃÀ´«Ã½.

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‘’ by Helena Rapp-Wright, Keng Tiong Ng, Derryn Grant, et al. is published in Addiction, journal of the Society for the Study of Addiction. DOI:  

[1] Sample sites are categorised into Northern and Southern regions of England. Specific sample locations are not identified due to confidentiality agreements. 

[2] The 20 compounds were: 

·       5-aminoisotonitazene (Opioids / Nitazenes)

·       6-acetylcodeine (Codeine)

·       Amphetamine (Speed)

·       Benzocaine (Cocaine cutting agent)

·       Benzoylecgonine (BZE) (Cocaine metabolite) 

·       Cocaethylene (Cocaine metabolite)

·       Cocaine 

·       6-monoacetylmorphine (6-MAM) (Heroin metabolite) 

·       Ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) (Methadone)

·       Isotonitazene (Opioids / Nitazenes)

·       Ketamine

·       Lidocaine (Anaesthetic and cocaine cutting agent)

·       Methadone 

·       Methamphetamine 

·       MDMA (Ecstasy)

·       Morphine

·       Norketamine (Ketamine metabolite) 

·       Phenacetin (Cocaine cutting agent) 

·       Procaine (Cocaine cutting agent)

·       Tetramisole (levamisole) (Cocaine cutting agent)