The data collection executed in 2025 covers 130 European cities. The sampling occurred in various processing plants and does not necessarily cover the whole cities’ area. The samples were collected over a one-week period between January and May 2025. The data shows the day when the drug residue was traced in the wastewater. Because of different durations of time since the moments of consumation to the processing in the wastewater facility, the EUDA considers Friday, Saturday, Sunday and Monday as weekend days, and Tuesday, Wednesday and Thursday as work week days.