The factors affecting the presence and growth of micro-organisms in piped networks are reviewed in this book, as are the practices of water supply organisations that can directly or indirectly influence their presence and growth. The information and conclusions are intended for policy makers and those responsible for formulating "Water Safety Plans" for the supply of drinking-water. It is also relevant to engineers and scientists who are responsible for water supply planning, operations and monitoring. The review shows that there are often public health reasons for adopting a more proactive approach to many of the traditional practices used in designing, operating and maintaining distribution networks, and to modifying the composition of the water that is fed into the network. Contents include the following topics: The microbiology of piped distribution systems and public health Composition of treated waters to minimise potential for microbiological changes Design and operation of distribution networks. Planned maintenance and survey of distribution systems Precautions during construction and repairs Small animals in drinking water distribution systems Risk management for distribution systems