Water stress is a major problem affecting the future of human societies around the world, particularly in the rural areas of the developing world. The Newsmakers article "Barrn to lush" (2 May, p. 593) highlighted an award for the invention of a new manual pump used for irrigation in rural Africa. We fully respect and admire the invention of efficient and affordable pumping systems to solve water shortage problems in rural areas. However, we are concerned about the intensive application of these new pumps to water-limited systems. (Letters)