Assessment of microbial growth potential of PVC flexible tubing in contact with drinking water

Plasticized polyvinyl chloride (PVCp) tubes are commonly used to transport drinking water to public coffee vending machines, ice machines or water fountains. In contrast to pipe materials, the materials used beyond the consumer's tap are considered to be in contact with food and need to comply with the European Regulation for food contact materials; this, however, does not contain specific requirements about the enhancement of microbial growth. The aims of this study were to estimate microbial growth on PVCp tubes which were used to transport water to the types of machines noted above and to compare two methods of evaluating their net microbial growth potential. Four PVCp brands were tested for enhancement of microbial growth using a tube immersion test (the original Biomass Production Potential test) and a new tube filling test. Under field operating conditions, significant amounts of active biofilm accumulated on the PVCp-I tubes thereby impacting on water quality. In the laboratory test, the amount of biofilms on PVCp tubes and bacterial regrowth in the water depended on brand and were influenced by the surface-to-volume (S/V) contact ratio. To protect consumers' health, the microbial growth promoting potential of PVCp tubes should be taken into consideration when these products are in contact with drinking water.