The quality and quantity of papers given at successive Health-related Water Microbiology Symposia continues to increase and the millennium meeting in Paris saw the highest ever number of delegates and presentations. Of necessity, these selected proceedings can only give a taste of the overall content of the Symposium but nevertheless, reflect on the growing interest and awareness of the importance of the microbial contamination of our environment and the implications for human health. Numerous contributions address different aspects of one of the waterborne diseases of most concern, cryptosporidiosis. However, this did not preclude reports on outbreaks of other diseases. Several contributions raised important questions: how should epidemiological data be interpreted? and what methods are valid for regulatory monitoring? were of particular interest. Newly developed analytical methods have allowed a greater range of pathogens to be detected. However, such techniques have little significance if they cannot be used for the practical evaluation of water quality and part of this is the acquiring of monitoring data upon which future treatment and policy decisions can be made. The 43 papers selected here cover: standards and quality assurance; risk assessment; epidemiology and disease outbreaks; monitoring; microbial survival; disinfection; wastewater treatment; methodology; and microbial toxins.