The point of compliance in the European Drinking Water Directive is the consumer's tap and thus a set of requirements for the quality of materials used in distribution systems is needed. On European level an approval scheme for construction products in contact with drinking water is under development. The Regulators Group proposed that the Biomass Production Potential (BPP) test should be the basis for assessment of microbial growth support properties of products in contact with drinking water. Due to a lack of data the goal of this study was to generate more information on the growth promoting properties of pipe materials of different origin using the BPP test. The pipe materials under study showed different capacity to enhance bacterial growth and their BPP values could be ranked: Cu < SS < PP < PEx < PE < PVCp. A positive correlation between the planktonic biomass (PB) and the BPP was observed. Materials with a high BPP and a relatively higher PB/BPP ratio had a higher potential to impair bacteriological water quality. The option for derivation of pass-fail criteria based on planktonic biomass was discussed.

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