Microbiological agents in drinking water
Addendum to the second edition of the Guidelines for drinking water quality
The microbiological review documents contained in this addendum supersede those previously published in Volumes 1 and 2 of the second edition of the Guidelines for drinking-water quality. Their more extensive coverage of individual pathogens reflects the need for more substantial review information to assist and support the further development of the Guidelines, particularly with respect to microbiological aspects.
The reviews do not conclude with the definition of “safe” or “tolerable” exposures as is the case with the analogous chemical reviews in the Guidelines. Microbiological quality may vary rapidly and widely and the health consequences of short-term exposures are typically significant. These features, combined with the incompleteness of current knowledge regarding the identity of waterborne pathogens and the poor availability and speed of analytical techniques for recognized pathogens, mean that defining safe exposures and monitoring their achievement are not generally the preferred means of control. Emphasis is therefore placed upon understanding conditions likely to ensure the safety of drinking-water supplies and monitoring their fulfilment more directly. The microbiology reviews published here therefore summarize current knowledge regarding quantitative aspects of transmission, attenuation, and removal of individual pathogens, and regarding the effectiveness of measures for the interruption of transmission.