Half eaten kebabs, a broken high heel, a puddle of sick in a shop doorway - typical remnants of a Saturday night out in the city. The European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) though, measure a much less visible indicator of a city's partying habits. Every year, they analyse
waste water samples around the continent for traces of illicit drugs
such as cocaine and MDMA.
Looking at traces of cocaine found at the weekend, the Swiss banking hub of Zürich is at the top of the scale with 1,109mg of the drug per one thousand people flowing through the drains. In a close second in Barcelona with 1,101mg and rounding off the top three is London (2016 data) with 999mg.