In 2010, a Europe-wide network (Sewage Analysis CORE Group — Europe) was established to standardise the approach to wastewater analysis and to coordinate national studies. Following the success of an initial study in 19 European cities in 2011 (Thomas et al., 2012), comparable  studies were undertaken over the following three years  covering up to 21 European countries. A standard protocol  and a common quality control exercise were used in all locations, which made it possible to directly compare illicit drug loads in Europe over a one-week period during four consecutive years.

[please note this guideline has been updated https://www.drugsandalcohol.ie/27397/ ]