In an arid land water is vital. Where rainfall is the only source of water, humans long ago found methods of collecting and concentrating it to supply their own needs and those of their stock and crops. Jordan is a region in which the methods used can be seen widely, not least in the fertile but ill-watered regions of the Southern Hauran along the border with Syria. This study explores water collection and use with special reference to two sites in that region, Deir el-Kahf and Umm el-Quttein. The data arise from fieldwork and the scrutiny of air photographs not normally available for Middle Eastern countries, and from comparison with evidence in other arid regions. The result is an insight into how water was collected, the potential of the enterprise, and its influence on both the location, extent, and morphology of individual sites, and on settlement patterns in general.