This text describes the processes involved in the design, installation and maintenance of effective plumbing systems. It also examines the microbiological, chemical, physical and financial risks associated with plumbing and emphasizes the importance of measures to conserve supplies of safe drinking-water. It is aimed at administrators and plumbers working in areas that are served by a mains drinking-water supply or sewerage system, or are about to install a mains drinking-water supply or sewerage system.