Potable water and biofilms: A review of the public health implications

Abstract

Water quality regulations require that potable water is supplied free of microbial pathogens. Although this is generally achieved, the incidence of waterborne outbreaks associated with potable water has been increasing over the last decade. Infection from pathogens such as Campylobacter spp., Salmonella spp., Cryptosporidium and Giardia and viral infections are on the increase, with the protozoans presenting their own particular problems due to chlorine resistance. Biofilm bacteria are generally more resistant to biocides than planktonic microorganisms. Thus, the water industry is presented with a problem, particularly with pathogens that enter the water system and become incorporated into biofilms. The presence of biofilms in potable water systems is discussed in terms of their development, structure, function and quantification on surfaces. Survival of specific water‐borne microbial pathogens is discussed in relation to their mode of growth in biofilms. Factors that influence growth such as nutrient availability, surface roughness and substrate composition are also reviewed.