Wastewater-based epidemiology (WBE) is a rapidly developing discipline that has the potential to monitor real-time data on regional and temporal differences regarding the use of illicit drugs. With WBE, metabolic products discharged for drug consumption are rapidly collected by sewage systems, which provide valuable evidence on the types and quantities of drugs consumed by a given community. In this study, the samples were collected from the wastewaters entering the facilities in Seyhan and Yuregir Waste Water Treatment Plants (WWTPs), in Adana Province. Composite wastewater analysis was performed by using liquid chromatography tandem mass spectrometry (LC-MS/MS) and the analysis revealed multiple drugs including cocaine and its main metabolite, benzoylecgonine, amphetamine-like stimulants including amphetamine, methamphetamine, 3,4-methylenedioxymethamp heta mine (MDMA), 3,4-methylenedioxyamphetamine (MDA), and 3,4-methylenedioxyethamphetamine (MDEA), opiates including morphine, codeine, heroin metabolite 6-acetylmorphine (6-MAM), the metabolite of cannabis, 11-nor-carboxy-THC (THC-COOH), and the main metabolite of 09-tetrahydrocannabinol (THC), 11-hydroxy (THC-OH). Mean drug consumption rates were as follows: cocaine, 0.18; amphetamine, 0.43; methamphetamine, 0.06; MDMA (ecstasy), 1.30; heroin, 1.03; THC (marijuana), 28.60 doses/day/1000 persons (15-64 years). The consumption rates for some illicit drugs showed a significant difference between seasons, regions, and weekdays-weekends. (C) 2018 Elsevier B.V. All rights reserved.