Under European Economic Area Agreement, Romania and Norway have developed a project for monitoring the quality of raw and potable water (from production technology until distribution) supplied by two Romanian water companies. In the present study was investigated the microbiological quality of water, which was compared with organic matter loads. Resulting free chlorine and trihalomethane compounds after disinfection processes were also analysed. The raw water collected from Danube hydrographical basin showed significant pollution with potential pathogenic microorganisms with faecal origin such as Salmonella sp., Escherichia coli, Enterobacter sp., Klebsiella pneumoniae, Proteus mirabilis, Citrobacter braakii, Providencia stuartii, and Enterococcus sp. Also other bacteria such as Pseudomonas aeruginosa, Acinetobacter, total number of bacteria at 22 and 37 °C were detected, being related to high water oxidability. The microbial load was reduced considerably after the disinfection process. However, the total number of bacteria at 22 or 37 °C was constantly higher than the imposed limit and Clostridium perfringens was identified occasionally. The tap water presented a sporadic microbial loading with Enterococcus sp., Pseudomonas aeruginosa and E. coli and constantly with total number of bacteria due to an improper water distribution network.