In scrap processing companies runoff rainwater is heavily loaded and has an appropriate water treatment business needs. On the basis of an inventory of the problem parameters, a selection will be made of suitable chemicals and materials for a physico-chemical water treatment (in the first instance: sand filtration, coagulation / flocculation followed by (slats) sedimentation and activated carbon filtration). This water treatment will be tested on laboratory and pilot-scale and to be integrated into a decision tree. This should enable the users on the basis of the taxation of their wastewater to choose the most efficient purification technique (according BATNEEC: best available technology not entailing excessive cost).