This report under the WHiRL research project by the Natural Resources Institute (NRI) identifies the potential unintended impacts of water harvesting so that, if at all possible they are avoided altogether, but if these do occur, they are recognised at an early stage and steps are taken to mitigate their affects. It highlights evidence that is emerging about water harvesting in semi-arid areas, on how water if used inappropriately, can lead to inequitable access to water resources and, in the extreme, to unreliable drinking water supplies.

Accepted wisdom is that rainfall should as far as possible be harvested where it falls and that these technologies are totally benign. Water balance studies in Andhra Pradesh and Karnataka show that water harvesting programmes impact significantly on patterns of water use and that this can result in distinct winners and losers. Winners include people who have improved access to water for productive purposes (e.g. irrigated agriculture) and losers include people whose access to water for domestic, productive and other purposes is reduced.

It is also clear that livelihood gains experienced by some “winners” can dissipate as competition for water resources increases and traditional drought coping strategies become less viable and/or increasingly expensive. The recommendation from the analysis presented in the report is that -

• Water harvesting should be encouraged but within an integrated or adaptive water resources management framework using procedures that weigh up the benefits and tradeoffs associated with altered patterns of water use. 
• In some cases, tradeoffs exist whereby the improved access and entitlements of users at one place or during one time period is at the expense of other user groups. Although these tradeoffs might be acceptable and, in some circumstances highly desirable, they should be taken explicit account of in strategic-level and village-level decision making processes.
• These ideally should be based on principles of integrated and adaptive water resource management.
• It is clear also that, as competition for water resources increases, much more attention needs to be given to identifying and mitigating the unintended negative impacts of water harvesting.

To download the report please click here