Chapters presented in this volume identify the commonalities of water management in societies across a wide range of ecological and cli-mate zones. This constructs a solid step towards the development of effective solutions to some acute water-related problems. A constant theme across time is the need for water, to fulfil which technologies have changed to make obtaining and controlling it easier. Technolo-gies evolve accordingly and become closely intertwined with social and developmental issues. Water technologies include irrigation canals, underground qanats, aqueducts, dams, and modern water technologies that desalinate or clean polluted water. Driessen and Abudanah investi-gate the chronology and extension of surviving ancient water-harvesting and -distribution systems in southern Jordan, some of which were still functioning not long ago. Their careful dating exercise contributes to a more reliable chronological reconstruction of some water-management features from Nabataean to Islamic times. The Udhruh qanat, a subter-ranean water system consisting of ‘vertical qanat shafts and horizontal underground water conduits’, might be dated to around 700–600 bc. While it undoubtedly required great innovation and investment to design and build such water-management systems, the authors point out that maintaining knowledge and experience was key to their successful func-tioning. This point is further emphasised by Bunbury in her geoarchae-ological survey of and textual information about water-management systems and ecological habitats in the Lower Nile. She proposes that the development of the qanat, and of other technologies, benefited from this knowledge accumulation. Knowledge about ecological cycles and past experiences of water management could be inherited and passed on to subsequent generations. Innovations that lead to intensification of water management (and agricultural production) often result from leg-acy derived from earlier societies (Bunbury, Chapter 3 in this volume) or are shaped by a collective memory of water management.