London is the number one city in Europe for cocaine-filled sewage, flushing away an average of 737mg per 1,000 people in any one week.
The estimate, calculated by the European Monitoring Centre for Drugs and Drug Addiction, is based on a comparison of 50 cities across the continent.
The UK capital beats Amsterdam, which comes in second place with 716mg. Other cities where the drug is popular are Barcelona, Copenhagen, Bristol and Antwerp. The lowest concentration can be found in the sewers of the small Icelandic town Jvaskyla – 1.2mg.
Previous research by the drugs body has already identified the UK as the European country which has the highest cocaine use among young adults, with four per cent of 15 to 34 year-olds admitting to taking the drug in the last year. Spain has the second highest intake.
Londoners are most likely to take it on Fridays and Saturdays, when the concentration in sewage peaks. it then falls back down again on Sunday and Monday.
London's high use of cocaine doesn't reflect its drug taking habits in general – in the case of both cannabis and ecstasy, it falls behind Amsterdam and other European cities.