Alteration phenomena of drinking water quality within water systems

Water quality of tanks and pipelines of drinking-water treatment works and of distribution networks may be altered by: release of reactant impurities; chemical or electrochemical reactions of water compounds with reactants and pipe materials; infiltration of contaminants; mixing with poor-quality water; microbiological contamination. This last phenomenon map occur even without infiltration from the external environment; iii fact, some microorganisms adhere To the pipe surfaces, causing biofilm formation, which, besides representing itself an health hazard, may yield significant functional problems, as biofouling and possibility of pipe corrosion. In the paper the phenomena which are responsible for water-quality alteration in treatment works and distribution systems are examined. In particular, the alteration phenomena determined by microorganism re-growth and disinfection by-products are described, considering the effects of both the water composition and the disinfectant adopted.