Water-supply engineering is a large and growing field of engineering. Up until the second half of the twentieth century water supply was rather a simple field. Water was abstracted, preferably from a reservoir with a protected catchment, or from wells, and after generally minimal treatment was put into the distribution network. Some supplies were derived from rivers and these supplies required more treatment. However where relatively poor-quality lowland rivers were used as a source, it was common to provide extensive storage prior to treatment, to allow self-purification of poor-quality water, and the subsequent treatment was often slow sand filtration, a process simple to operate and robust.

Distribution systems were also simple. In the UK we generally pumped water to water towers or service reservoirs located at high points, and from there the water served the supply zones by gravity. There was little or no flow measurement, except at treatment works, and leakage was generally not a major concern, not least because leakage rates could not be determined. However as far back as 1885, Alexander Binnie, forefather of one of the authors, was working to introduce metered water-supply zones with measurement and recording of night flows in Bradford, to allow wastage and leakage to be reduced. ^[1] Bradford used inspectors to visit houses to check water pipes and fittings.

The water-quality requirement was that the water be wholesome. In practice, the only quality standards were microbiological and regular water sampling and analyses were limited to microbiological examination and testing of...