In the framework of the European Acceptance Scheme for approval and certification of products in contacts with drinking water, the Biomass Production Potential (BPP) test for assessment the microbial growth support properties of these products has been harmonized, funded mainly by EC. The objectives of this study were to elucidate the BPP procedure and evaluate the growth promoting properties of selected pipe materials. The tested pipe materials showed large differences in their microbial growth support potential and the BPP values can be ranked: glass < Cu < SS < PP < PEx < PE < PVCp. The tested materials differed in the contribution of attached (biofilm) biomass to the total BPP. Materials characterized by a high BPP value and a relative lower ratio between attached biomass and total BPP have a higher potential to impair drinking water quality.