Wastewater data uncovers drug use in European cities
Cocaine and ketamine on the rise, while ecstasy losing popularity
Drugs leave traces. Take ecstasy at a party or smoke a joint, and chemical residues from your body eventually pass into the sewer system. From there, they flow to wastewater treatment plants—where scientists can measure them and estimate how much of different drugs people are using in specific cities.
Those measurements, published today by the European Union Drug Agency (EUDA), reveal the latest trends in drug consumption across Europe. Cocaine consumption has once again reached record levels, rising by 22 percent across monitored cities compared with the previous year. Ketamine use is also climbing sharply, increasing by 41 percent in the same locations. Ecstasy, however, appears to be losing popularity, seemingly replaced by other synthetic drugs.
How scientists estimate drug consumption through wastewater?
The newest data released by the Europe-wide SCORE group and European Union Drugs Agency (EUDA) in March 2026 comes from 130 cities in 28 European countries. To collect the data, wastewater samples were analyzed over a one-week period set between January and May of 2025. Although most of the measurements took place in the same period, the individual cities’ participation was carefully scheduled around local festivals, events and peak tourist seasons to prevent distortions in the results. Wastewater samples from approximately 72 million people were analysed of five stimulant drugs (cocaine, MDMA, methamphetamine, amphetamine, ketamine) and cannabis. Heroine for example is not measured, as its metabolites are unstable in water.
Since most drugs are illegal in most countries, traditional methods such as surveys or sales statistics are insufficient. Therefore, wastewater analysis is one of the only ways to measure drug usage across populations. It works like this: Let’s take cocaine as an example. Whenever it is used, the body’s metabolism breaks down its chemical compounds. After this biochemical process, cocaine becomes a mixture of compounds, including its main metabolite: benzoylecgonine. This metabolite – and those of all drugs – end up in the toilet, eventually reaching the sewer network, most likely geographically close to where the drug was consumed. Through the sewer network, the wastewater reaches the closest treatment plant, where samples are collected and analyzed in a laboratory. The amount of drug residues is then recalculated per 1000 people per day. By standardising this procedure, it ultimately allows for the calculation of the amounts of drugs used across different European cities.
The latest wastewater analysis covers 130 cities in 28 European countries. The comparative study—the largest of its kind—is conducted by the Europe-wide scientific network SCORE group, which collects samples via local partners together with the EUDA. The SCORE group has used wastewater analysis since 2011 to estimate illicit drug consumption in cities. The analysis tracks five stimulant drugs—amphetamine, cocaine, methamphetamine, MDMA, and ketamine—as well as cannabis.
Cocaine on the rise once again
Cocaine, the most commonly used illicit drug after cannabis, continues a decade-long upward trend in Europe. Of the 88 cities with data for both 2024 and 2025, 63 reported an increase. Traditionally, the highest consumption levels are found in Western and Southern Europe, and the newly released data confirm this trend. However, cocaine traces—often increasing—can now also be found in Eastern European cities.
This year’s cocaine ranking includes the only two measured cities in the UK, Middlesbrough and Bristol, together with Catalonia. The Catalan capital, Barcelona, is one of the cities with the steepest increases compared to the year before—185 percent. Similarly, the Spanish city of Lleida in the same region recorded an increase of more than 100 percent. High residues were also recorded in nearby Tarragona in previous years; however, this time the city decided not to take part in the measurement.
The highest levels continue to be found in Western Europe, especially in the Netherlands, Belgium, and Switzerland, with cities such as Amsterdam, Rotterdam, Brussels, Antwerp, Zurich, and Geneva maintaining their positions in the top 20. However, in year-on-year comparisons, consumption levels in these cities remain rather stable or have slightly decreased.
Cities such as Barcelona, Amsterdam, and Antwerp have one thing in common: they are all port cities serving as important entry points for cocaine trafficked to Europe from Latin America. Belgium, Spain, and the Netherlands are the three European countries that have repeatedly reported the highest numbers of cocaine seizures over the years. According to the latest data from 2023, these three countries alone account for 72 percent of drug seizures in the EU.
Record seizures suggest the increasing establishment of Europe as both a major transport hub for cocaine and a major consumer market. High levels of cocaine consumption in trafficking hotspot cities can be linked to easier access to the drug or its lower price. However, consumption patterns are much more complex and are driven by many other factors, such as the popularity of certain drugs, perceptions of their health impact, the nightlife economy of a city, and others.
For these reasons, the data for 2025 revealed a surprising finding: the popularity of ecstasy is in decline.
Ecstasy party might be over
Overall MDMA loads in wastewater dropped by 16 percent between 2024 and 2025. Namely, of the 79 cities with data for both 2024 and 2025, 53 reported a decrease. The recent decline is even more pronounced than the one observed in 2020, when almost half of the cities reported decreases during COVID-19 nightlife closures.
The impact of the pandemic was especially notable in the case of ecstasy, which is considered to have the most straightforward association with nightlife and parties. This is supported by the analysis of consumption by days of the week—MDMA clearly dominates weekend consumption patterns.
What is behind this sudden drop? According to João Pedro Matias, a scientific analyst at the EUDA, ecstasy might increasingly be replaced by other stimulant drugs gaining popularity among young people. “The synthetic drug market is dynamic. Cathinones are now cheaper and more available. Some, especially mephedrone, have similar effects to ecstasy, and they act faster,” explains Matias. According to him, the trend is visible not only in surveys among young consumers, but also in the increasing number of seizures. The trend is also reflected in the types of drugs seized in dismantled labs, which, according to him, increasingly focus on the production of a variety of substances.
In one of the MDMA hotspots, Antwerp in Belgium, usage is almost one quarter of what it was in 2023. The current level is comparable to that of 2020 during strict COVID restrictions. However, the top rankings have not changed much since last year: four Dutch cities occupy the leading positions, with Amsterdam far ahead despite the recent decline.
The opposite trend has been recorded for ketamine, suggesting its increasing popularity.
Ketamine on the rise
Ketamine usage has recorded an increase in the majority of cities, similarly to cocaine. Among the 68 cities with data for both 2024 and 2025, 47 reported an increase. Capital cities Amsterdam and Berlin dominate the ranking in continental Europe, only beaten by England’s Bristol.
“Bristol is known for being a ketamine transport hub, as well as a nightlife economy city. It is the heaviest ket city in the world,” says Josh Torrance, a Bristol-based criminologist, adding that people often use ketamine together with cocaine, whose levels have also increased significantly in Bristol.
However, ketamine is far from being a local Bristol issue. National statistics data for the whole of England show that the number of adults starting treatment for ketamine problems has more than tripled since 2021.
“Ketamine use has become a serious problem in the whole of the UK. A much larger number of people use it on a daily basis in comparison to the rest of Europe,” explains Torrance. The key driver is the low price, he claims: “One can buy a gram of ketamine for 10 to 15 pounds.”
The substance has been included in wastewater measurement only since 2022, following its labelling as a new popular drug on the rise. It is originally known for its medical use for anaesthesia and pain relief. For this reason, there have been many debates about how much of its consumption can be ascribed to medical use and how much to recreational use.
Between 2024 and 2025, ketamine consumption has increased in 61 percent of the cities measured. Similarly, ketamine seizures in Europe have increased to 3.5 tonnes from 200 kg in 2016. However, medical demand appears to have remained stable during this time. That suggests that the increase in ketamine can only be explained by its growing popularity as a recreational drug.
“The clearest indication from the wastewater data that ketamine is used recreationally as well as in medicine is that the amounts detected are higher at weekends. This is similar to what is observed with other drugs that are used in recreational settings, like cocaine and MDMA,” adds Andrew Cunningham, EUDA’s senior analyst, who led a recently published research study into ketamine use and the market. On the other hand, cannabis usage is distributed more evenly over the week, as are speed and meth, as the analysis of consumption across the week reveals.
Meth and Speed hotspots
Amphetamine is traditionally present in Nordic countries, while crystal meth traditionally ranks high in Czech and Slovak cities.
The Czech city of České Budějovice is replacing another Czech city, Ústí nad Labem, as number one in meth across all measured European cities. The reason is a 29 percent increase compared to the previous year. Czech cities occupy the first five positions in the meth ranking, including the capital Prague, where all measured substances increased compared to the year before.
Czechia’s primacy is linked to the tradition of meth self-production dating back to pre-revolutionary times. However, in recent years, we have also seen the rise of meth in neighbouring cities, such as Erfurt and Chemnitz in Germany. As Věra Očenášková, a Czech expert from the T. G. Masaryk Water Institute, previously told UJN, the increase in meth consumption in bordering cities can be explained by the “growing export of meth from Czechia.”
This cross-border aspect is highlighted by the fact that during the COVID year, all Eastern German cities recorded a drop in meth consumption, while Czech consumption remained stable. High meth loads were also found in two Slovak cities included in the measurement.
In the above-mentioned cities of Central Europe with traditionally high meth consumption, this time we can also see a sudden increase in speed. The increase in speed is even sharper than in the case of meth. In the Slovak town of Piešťany, speed consumption increased by almost 345 percent compared to the year before. This trend is followed by the capital Bratislava, with a less dramatic increase.
According to Matias, one of the methods of meth production, the so-called “Mexican method,” also allows the production of amphetamine. More of these labs are emerging, according to him.
Nevertheless, the increased values in Central Europe are, in overall comparison, still much lower than in the traditional speed hotspots: the Nordic countries, the Netherlands, and Belgium.
The current ranking for speed consumption is led by a smaller Belgian town close to Antwerp, Hasselt. The city is included in the analysis for the first time, with many new cities from Belgium joining the measurement. Moreover, Hasselt also ranks high, in sixth place, in ketamine consumption.
“We likely see an influence from labs that produce synthetic drugs. Speed is one of the substances for which the effect of dumping cannot yet be completely ruled out. Moreover, the latest available figures from the federal police also show that the majority of drug labs were discovered in the provinces of Limburg and Antwerp,” suggests Maarten Leemans from the Drugs Unit at Sciensano for Apache.
However, Matias points out that “all data is checked for dumping, and our methodology is designed so that it detects this and removes dumping episodes.”
Especially in the case of speed, we can see many rather small cities in the top rankings. In another smaller Austrian city, which ranks high in speed consumption compared to the rest of the country, Herbert Dutter-Kohlhofer, a local drug addiction coordinator, told Wiener Zeitung: “The district is heavily industrialized. There is a lot of shift work here, for example in larger companies, and we have clients who take amphetamines to get through night shifts. At the same time, we often see little recognition among this group that a drug problem exists.”
EUDA points out that the difference in consumption between bigger and smaller cities has been shrinking—with the exception of cocaine and MDMA.
Cannabis rather decreasing, despite legalisations
For the past years, cannabis measurements have provided a rather mixed picture, with slightly more cities recording declines than increases. This year is no different.
The top 10 list is occupied mainly by cities from Germany, where cannabis results were reported for the first time, and Slovenia. Small personal possession is not a criminal offence, but producing and selling are still illegal. In Germany, the recently passed legalization in 2024 legalized cannabis, even though commercial shops are still not allowed.
According to Matias, it is very hard to observe any clear correlation between legalization policies and the consumption estimated from wastewater analysis. There are recorded cases of both—consumption in the past has both increased and decreased in such cases. “It’s very hard to see the impact of drug law on the level of the whole population. To see a level of increase or decrease in use, it takes time,” adds Matias.
German studies based on surveys, however, suggest that recent nationwide legalization did not lead to an increase in usage. As Eva Hoch, professor of Clinical Psychology and Psychotherapy at Charlotte Fresenius University in Munich, told our partner Tagesspiegel: “Our trend analyses show that cannabis use among adults had already increased significantly in Germany even before legalization. Since then, the number of users has continued to rise slightly, but not to a statistically significant extent. We will need several more years to assess the long-term effects of legalization.”
Another country with a liberal policy is Portugal. There, possession of all drugs for personal use is decriminalised, but not legalized. This means the substances are still illegal, yet possessing a small amount is treated as an administrative offence rather than a criminal one.
Lisbon is one of the three cities this year where all measured substances decreased.
The most recent data, collected in 2023, shows that Portugal’s overdose death rate is about 6 per million, roughly four times lower than the EU average of about 25 per million. Matias, who is himself based in Lisbon, confirms that in the aftermath of the decriminalisation of illicit drugs in 2001, the data showed both a decline in usage and, especially, in harm-related statistics. However, he highlights that such impact was not only about the change in criminal law, but mainly about an emphasis on policies such as treatment, prevention, and harm reduction.
Cities under the sight
Wastewater-based epidemiology is considered the most precise available method for estimating illicit drug consumption. However, some cities are not very keen to take part in the measurement.
Some still prefer to rely on traditional surveys. “Surveys of course also bring very valuable results, hence the best way is just to complement findings from both,” says João Pedro Matias.
To give an example: wastewater analysis can, as accurately as possible, reveal how much of a drug was consumed in a specific area served by a wastewater facility. But it cannot draw any conclusions about whether it is mainly young people consuming the drug. For such findings, representative surveys combined with other data, such as treatment and medical statistics, are useful.
Combining various data sources was precisely the reason why Matias wasn’t really surprised when he first saw the new wastewater data. “We were getting signals about MDMA losing its popularity. The drop came a bit earlier than I assumed, but otherwise no surprise,” he says, shrugging his shoulders.
One of the “signals” came from a survey among young people aged 15 to 24, revealing an increased popularity of other synthetic drugs, which have similar effects to ecstasy and are, moreover, cheaper.
However, it is not only a more traditional approach or financial constraints that prevent cities from taking part in wastewater analysis.
In Berlin, after our partner Tagesspiegel inquired for two years why the city was no longer taking part in the analysis, the local authority pledged to rejoin. As a result, Berlin’s data are once again included in this year’s rankings.
On the other hand, the European ranking of cocaine consumption notably misses the Spanish coastal city of Tarragona this time. Last year, the city of 150,000 inhabitants south of Barcelona occupied top positions, outranking cities such as Amsterdam, Zurich, and Barcelona itself. This was not an anomaly—Tarragona ranked second in cocaine use in both the 2024 and 2023 measurements.
“Tarragona is a place with a huge volume of human interactions: there are large numbers of people working in the refineries, and many truck drivers constantly coming and going from the area,” explains to our partner El Diário Antoni Llort, anthropologist at the Universitat Rovira i Virgili who has studied drug consumption in the area for years. “I would also say that, as is the case in the rest of Spain, cocaine use is becoming increasingly normalized across the population. And Tarragona, in particular, is a drug entry point: supply is direct, the price is affordable and the quality is higher than what you would normally find in Barcelona.”
However, Tarragona City Council decided not to allow sample collection at its wastewater plant anymore. In response to our partner El Diario, the city justified its absence from the dataset by citing “weaknesses” in the study, which “place Tarragona in an incorrect ranking.” It claimed that the Europe-wide results are not comparable and that the “reality of the city is not adequately represented” because the wastewater facility also serves neighbouring towns.
Having precise information about the area served by the Tarragona wastewater plant, the UJN team can confirm that the facility serves, in addition to the city itself, two other towns. However, these have a combined population of around ten thousand inhabitants, meaning they could hardly have influenced the overall results in any significant way.
“All labs across Europe carry out rigorous quality control tests; otherwise, the data are simply not published,” says Matias, adding that the Tarragona samples were even verified by another Spanish research team, which confirmed the same results.
The results could theoretically have been influenced by the high number of tourists in the city at the time of sample collection. However, researchers always select sampling periods so that they do not coincide with festivals, events, or peak tourist seasons.
The more wastewater plants included in the analysis, the clearer the overall picture for the public and policymakers. “Wastewater analysis helps us track shifts in drug consumption early, to better understand where attention and resources are needed and to inform evidence-based public health and policy responses across Europe,” says Dr Lorraine Nolan, EUDA Executive Director.