For the seventh time, KWR has published results on the presence of drugs in the sewers of Amsterdam, Eindhoven and Utrecht

Netherlands number 1 user of XTC in Europe

The European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) today (11:00 CET) published the results of the monitoring of drugs in the sewage water of large cities. Professor Pim de Voogt of KWR once again studied the cities of Amsterdam, Utrecht and Eindhoven. This is the seventh year that these results have been published for the Netherlands. Over the last few years, KWR has also occasionally conducted such monitoring for twenty-odd small Dutch towns. Conclusion 1: the differences between large cities and small towns are minor. Conclusion 2: the consumption of MDMA (XCT) shows a rising trend over 2011-2017.

For the sewage water research, researchers in almost 60 European cities collected chemical analyses of wastewater samples taken during a single week in March. The focus was on cocaine, amphetamine, ecstasy and methamphetamine. KWR collaborates in this research with Waterboard de Dommel (Eindhoven), Waternet (Amsterdam) and Waterboard Hoogheemraadschap Stichtse Rijnlanden (Utrecht).

Confrontational numbers not popular

Because the long-running sewage water study only presents a picture of drug use in the three large cities, professor Pim de Voogt of KWR reiterates his call for a larger scale study. ‘So far, only 20 of the 390 municipalities in the Netherlands have had a sewage study done. The studies present the town authorities with confrontational drug-use numbers, which then generate heated discussions when they’re made public. The media shower them with mostly negative coverage on the basis of our findings. The commendable nature of the initiative shown by the authorities in an effort to get a good picture of their drug problem is ignored. A couple of days later peace returns to the Netherlands.’ See also: Sewage research becomes policy instrument for towns.

‘To be clear,’ says De Voogt, ‘the cities of Amsterdam, Utrecht and Eindhoven did not commission the study. KWR carries out the sewage water research in the cities in collaboration with the waterboards. The small towns, for their part, did commission KWR for the research.’

2017 results in detail

KWR analysed the Dutch results over the last seven years (2011-2017) for the cities of Amsterdam, Utrecht and Eindhoven, and reported them to the EMCDDA.


Based on the measurements, calculations were made of the daily loads of benzoylecgonine (as a measure for cocaine), MDMA (ecstasy), amphetamine and methamphetamine. The benzoylecgonine loads were converted into consumption as pure cocaine. Cocaine consumption in the Netherlands was relatively stable over 2011-2017. Amsterdam clearly has the highest consumption level among the Dutch cities studied. The average cocaine consumption in the small towns studied in recent years is comparable to that of the city of Utrecht.

# No data available. The chart above shows the consumption of pure cocaine which is derived from the calculated loads of cocaine’s metabolite (benzoylecgonine). The chart shows the consumption of cocaine, which contrasts with the other five substances for which only the loads are shown. The reason for this is that only in the case of cocaine do we have a precise idea of how much of the drug’s metabolite is excreted by the body following its consumption. Thus the cocaine consumption can be determined through backward calculation. Moreover, the consumption levels shown in the chart refer to 100% pure substance. The average purity of street cocaine is about 67% (Trimbos Institute data for 2016). This means that the numbers in the chart should be multiplied by 1.5 to arrive at the consumption levels of cocaine bought on the street or from dealers.


Methamphetamine is consumed very little in the Netherlands. In recent years, methamphetamine was only detected twice in Utrecht and Eindhoven, while in Amsterdam the loads are beginning to increase. Interestingly, methamphetamine has also been found in the wastewater of a several small towns.

# No data available.


With regard to the party drug MDMA (ecstasy), the 2017 numbers show, as in recent years, that the Netherlands has the highest consumption levels in all of Europe. Utrecht shows a more or less constant load over 2012-2017 (in 2011 an MDMA dump was recorded in the city). In Eindhoven several direct MDMA dumps were recorded over the last few years, and only in 2015 and 2016 was there evidence of a ‘normal’ MDMA consumption pattern (with increased consumption on weekends). Amsterdam shows a rise in the MDMA load over 2011-2017; this could have been caused in part by an increase of the MDMA content per tablet over the period (Trimbos Institute data). The average MDMA load in the small towns is lower than that found in the larger cities studied.

* Not derived from consumption. # No data available.

Average MDMA loads in Amsterdam plotted against the average amount of MDMA in XTC (MDMA) tablets per year (Trimbos Institute data).


Amphetamine consumption in Utrecht over 2011-2017 remained relatively stable and was at average European levels. In Eindhoven, as was the case in several recent years, a very high load was recorded in 2017, which is probably attributable to direct discharges in the sewers. Such dumps have no impact on the treatment capacity of Eindhoven’s regional wastewater treatment plant (WWTP). On average, the small towns in the Netherlands show higher amphetamine loads than do Amsterdam and Utrecht.

Not derived from consumption. # No data available.

For more information about KWR’s sewage water research over the last 7 years see Drugs of abuse.