The purpose of a water distribution system is to deliver safe drinking water from water treatment plant (WTP) to each consumer. In contrast to WTP, the transportation of drinking water through pipelines networks and distribution system is closed and goes through large areas to reach the consumers downstream. Bacterial growth in a drinking water distribution system mainly occurs on the internal surface of the materials of pipes. In this research a pilot system has been built and connected with Benha water distribution system to study the factor effecting in biofilm formation on different pipes materials (uPVC- GRP - Concrete - Cast Iron) at different exposure periods (15, 30, 60, 120 days) to determine the best choice from pipe materials for use in water distribution system and that reduce bacteria regrowth through the system. The experimental results generally showed that uPVC pipes have the lowest value for the total number of bacteria grown as biofilms on uPVC surface, while the concrete pipes have the highest values. In addition, the GRP pipes had the second grade for grown biofilms on its surface after uPVC pipes, then, cast iron coupons came in third grade in this respect before concrete pipes. Therefore, the final arrangement for pipes used in the study with respect to the formation of biofilms on their surfaces are in the order: uPVC < GRP < CAST IRON < CONCRET. The total number of bacteria formed in the biofilm on different materials has also increased with increase of temperature from 22 oC to 37 oC.