Products are tested by the Belgian federation for the water sector (Belgaqua) and tested for their suitability to be able to come into contact with drinking water. On top of that there is usually a certification, which means that a certification body mandated by the BUtgb with a set frequency external supervision exercises the conformity of production with the published approval. This review or check is described in a convention that is drawn up when the ATF is granted. This agreement indicates how the manufacturer organizes his own control of the production and which external tests will be carried out.