Biofilms and Drinking Water

Ursula Obst
Forschungszentrum Karlsruhe, Institut für Technische Chemie, Bereich Wasser- und Geotechnologie (ITC-WGT)
Abt. Mikrobiologie natürlicher und technischer Grenzflächen
Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen


 The preferred and dominant life forms of environmental microorganisms are biofilms adherent to surfaces. Thus, biofilm-forming bacteria are present in any source water for drinking water treatment such as soil bacteria in groundwater and mat-forming and fecal bacteria in river water. Biofilms may colonize and clog water transporting pipes in wells but can also support cleaning of water during natural (bankment) and technical filtration steps. Treatment and disinfection do not completely eliminate but only reduce the number of biofilm-forming bacteria. Surviving bacteria are often able to express enhanced persistence and form again biofilms shortly after water treatment steps. Thus, biofilms are transported into the pipes, are always present in the distribution net and cannot be completely avoided. They can act as a shelter for pathogens and may induce corrosion of pipe material or smell and taste problems. The manipulation of biofilms by special processing or construction materials during drinking water treatment and distribution is one of the big challenges in water industry.

Keywords : biofilm, dringking water, bacteria, water treatment