Application of microbiological analyses for the assessment of the regrowth potential in drinking water distribution systems

In the paper microbial regrowth potential in water distribution system was characterized basing on determination of the number of heterotrophic obligatory psychrophilic bacteria, bacteria from the genus Pseudomonas growing at 7 degrees, 30 degrees, and 42 degrees C, bacteria of the family Enterobacteriaceae, bacteria from the genera Enterococcus, Campylobacter and Yersinia, coagulase-positive staphylococci, Cl. perfringens and microscopic fungi in the water phase, biomass "suspended' in it and pipe sediments. It was stated that microbial regrowth occurred already on the sampling locations situated 4.2 divided by 4.3 km from Water Treatment Work (WTW), being especially substantial at 10,10,3 km. It was proved by the increased number of obligatory psychrophilic heterotrophic bacteria, pigmented bacteria, bacteria from the genus Pseudomonas growing at 7 degrees, 30 degrees, and 42 degrees C both in water phase and biomass "suspended" in it. The main reservoir of hygienically relevant bacteria and fungi isn't water phase but biomass "suspended" in it which isn't monitored during routine control analyses carried out by WTW laboratories.