Focusing attention on gravity-fed water-flow systems in mediaeval cities and monasteries, this study of water technology in the Middle Ages challenges the view that hydraulic engineering died with the Romans and remained moribund until the Renaissance. Roberta Magnusson explores the systems' technologies - how they worked, what uses the water served - and also the social rifts that created struggles over access to this basic necessity. The author is mindful of theoretical questions about what hastens technological change and how society and technology mutually influence one another. Archaeological, historical and literary evidence vividly depicts those who designed, constructed and used mediaeval water systems and demonstrates a shift from a public-administrative to a private-innovative framework - one that argues for the importance of local initiatives.