Conditions favouring coliform and HPC bacterial growth in drinking- water and on water contact surfaces

A biofilm is a collection of organic and inorganic, living and dead material collected on a surface. It may be a complete film, or, more commonly in water systems, it is a small patch on a pipe surface. Biofilms in drinking-water pipe networks can be responsible for a wide range of water quality and operational problems. Biofilms contribute to loss of distribution system disinfectant residuals, increased bacterial levels, reduction of dissolved oxygen, taste and odour changes, red or black water problems due to iron-or sulfate-reducing bacteria, microbial influenced corrosion, hydraulic roughness and reduced material life (Characklis and Marshall 1990).