•The custodian of the resource holds the rights of property (including the rights of intellectual property) to the geographic files

•The custodian grants the user the right to use the data for his internal use.

•Commercial use of the data under any form is strictly forbidden

•Custodian’s name must be mentioned each time the data are being used publically.

•The custodian of the resource holds the rights of property (including the rights of intellectual property) to the geographic files

•The custodian grants the user the right to use the data for his internal use.

•Commercial use of the data under any form is strictly forbidden

•Custodian’s name must be mentioned each time the data are being used publically.

The surveillance started in 2025 for the whole country.

Samples are collected during 7 consecutive days in spring at each selected wastewater treatment plant (WWTP) using 24-hour volume proportional or time proportional auto-samplers. After transport at 4°C, samples are frozen at -20°C until analyzed. The samples are analyzed by the Toxicological Centre of the University of Antwerp. After solid phase extraction, the samples are analyzed LC-MS/MS.

The quality of the results is checked and validated at the laboratory level. If the quality is insufficient, additional analyzes are performed. Once received by the data manager, the laboratory results undergo a second validation before being integrated in the database.

The 24 hours-representative flow rates of each WWTP are collected using flowmeters and are provided by the wastewater agencies (Hydria and Aquiris for the WWTPs of Brussels, Société Publique de Gestion de l'Eau (SPGE) for the WWTPs of Wallonia and Aquafin for the WWTPs of Flanders). Domestic inhabitant equivalents (IE) are used to estimate the population coverage of each WWTP. IE are based on several data sources (population data, building type data, connection to the network and WWTPs geographical coverage data). IE are provided by SPGE in Wallonia and by the Vlaamse Milieumaatschappij (VMM) in Flanders. In Brussels the population is estimated based on the data provided by Statbel. The data provided by the wastewater agencies and VMM are validated by the data manager before being integrated in the database.