The wastewater monitoring network investigates the discharges of enterprises and public sewage treatment plants. The measurements by the Flemish Environment Agency (VMM) are done in function of the calculation of the correct levies on waste water and the regional and international reporting duties. The employees of the waste water monitoring network also check the measurements on enterprise waste water done by independent acknowledged labs . The measuring results are primarily meant for the development of an emission-inventory. Data which are recorded in this inventory are consulted by users within and outside the VMM. The data on the sewage treatment plants in the emission inventory are also used to calculate the efficiency of the plant in order to get an idea about the efficient working of the entire water purification infrastructure.