There are many dimensions to increasing water productivity for agriculture: use of drought-resistant crop varieties, better tillage techniques, and improved appropriate technologies such as treadle pumps are among them. The articles in this issue of ALN, however, focus primarily on water harvesting and wastewater re-use as means of improving rural water use efficiency for both agricultural and domestic purposes.

The first article, by Hendrik Bruins and colleagues, broadly explores the potential for rainwater harvesting as a local-level drought mitigation strategy for arid-zone pastoralists. The authors report on a study of three regions — the Turkana and Kajiado Districts of Kenya and the southern Negev Desert of Israel — that share a long pastoral tradition but otherwise differ in many ways. Their thesis is that pastoralism is a highly rational and effective food production system in regions too dry for rainfed agriculture, but that changing socioeconomic conditions require pastoralism management changes as well. Among these changes, supplementary fodder use and auxiliary farming using rainwater harvesting techniques are shown to have strong potential for increasing water productivity and reducing drought vulnerability among these pastoral populations.

The next article turns to water harvesting for domestic use. For villages in the Thar Desert of western Rajasthan, poor groundwater quality and scarcity of treated drinking water make rainwater an essential drinking water source. As authors Rob Reed and colleagues explain, many traditional systems exist in this region to capture and store rainwater, especially during the monsoon rains that provide most of the area's precipitation. However, because the water is then stored for long periods of time in various communal ponds, reservoirs and cisterns, waterborne disease is a serious threat to the health of local populations. In broader socioeconomic terms this also represents a significant loss to the local labor force and associated productivity and social wellbeing. The authors report on a study conducted to see whether solar disinfection could be "a useful means of providing rural villagers with an alternative source of drinking water." Results of the field trials were encouraging, showing measurable reductions in the incidence of common waterborne diseases through use of easily produced, inexpensive containers.

Third is an essay that returns to the Middle East and a heart-felt consideration of the possible future of an ancient water harvesting technology. In this case, however, it is groundwater rather than rainwater that is being tapped, by means of "qanats," ancient and ingeniously constructed irrigation tunnels dug millenia ago in the deserts of countries such as Syria. Although many qanats have fallen into disuse, and although they undoubtedly could not provide all the water needs of large-scale commercial farming enterprises, author Joshka Wessels believes they still hold great potential as an alternative water source for local and small-scale agriculture. In this essay she speaks of her own experiences restoring qanats in Syria and reflects on their potential for the future.

Finally, the fourth article turns to consideration of use of wastewater use for agriculture. This practice of course is also not new; according to IWMI's 2004 survey Wastewater use in irrigated agriculture: Confronting the livelihood and environmental realities, wastewater is used to irrigate 10% of the world's crops. Although untreated wastewater may contain dangerous pathogens, treated wastewater could become an important source of irrigation water for dryland agriculture. As author Erin Addison explains, an ambitious wastewater re-use project in the Petra Region of Jordan is employing drip irrigation to deliver treated effluent from the Wadi Musa Wastewater Treatment Plant to the fields of a demonstration farm adjacent to the plant. Designed to tackle diverse problems such as public health and wastewater management, land degradation, and local income loss at one and the same time, the project has faced substantial criticism and challenges from important stakeholders on its path to implementation. Through hard work, persistence, and strong vision from various local leaders, these challenges have been met and largely dealt with. The resulting tale is as interesting for what it says about the challenges of designing sustainable regional development projects as for its details about the physical set-up of this particular project.

Taken together these articles indicate great potential for more efficient use of available rural water resources for both domestic and agricultural use. But this is only a beginning. As Sandra Postel wrote in her 2001 article, "Growing more food with less," published in the Scientific American, "...broader societal changes—including slower population growth and reduced consumption—will also be necessary. Beginning with Sumeria, history warns against complacency when it comes to our agricultural foundation. With so many threats to the sustainability and productivity of our modern irrigation base now evident, it is a lesson worth heeding."