3. Illicit Drugs in the Urban Water Cycle

In recent years, the presence of human-use compounds in the aquatic environment has been recognized as an important issue in environmental chemistry. Among them, illicit drugs have been described as a new unexpected group of water contaminants with potent psychoactive properties and unknown effects to the aquatic environment.

The presence of these drugs in water resources is of rising concern and several studies are being conducted all over the world estimating discharged levels of drugs of abuse. In this chapter, a summary of the last works studying and reporting the occurrence of illicit drugs in water resources is performed. Up to now, drugs of abuse have been already detected in wastewaters and surface waters in the USA, Italy, Germany, the UK and Spain. These drugs reach wastewater treatment plants either unaltered or in their main metabolite form. Depending on the removal efficiencies, they can persist through wastewater treatment and be detected in receiving waters, which in some cases are used for drinking water production. The presence of these compounds in raw waters and their elimination through the drinking water treatment must be considered as an issue with regard to the quality of water supplies.