The treadle pump is a simple suction pump powered by a human operator. These pumps are used principally to draw water from subsurface reservoirs for the purpose of irrigation, although they can certainly provide water for other uses as well. Pumps of this sort are a relatively recent development, but they have come into widespread use in Asia and Africa, where they provide inexpensive access to water for irrigation without the need for electrical power or other industrial infrastructure.
A treadle pump consists of two treadles, which average five or six feet in length and are mounted to a central pivot point. An operator drives the two treadles attached to this pump by using the same muscles that he or she would use to walk and the same gait as well. Pistons attached to the treadles are compressed by this motion, and produce suction, which is used to draw water from a nearby lake or stream or up from a borehole.
These pumps are very inexpensive and offer access to irrigation water to farmers and communities that might otherwise not be able to afford it. Almost all of the components of a treadle pump can be constructed from whatever sturdy materials are locally available. Treadles and supports can be made from metal, plastic, bamboo or other wood, and replacements can be produced quite cheaply for parts that break. Only a small number of mechanical parts require more machining, and these are simple and inexpensive.
The modest $20 to $80 US dollar (USD) price of a treadle pump means that even very poor farmers can often afford them. The purchase of a pump, in turn, will increase agricultural productivity. These pumps form part of several plans to increase the ability of local farmers in poorer regions to be relatively self-sufficient and to reduce the need to rely on more expensive or energy-intensive technologies.
Farmers making use of treadle pumps are often able to grow additional crops during the course of a year or to plant crops with a higher cash or nutritional yield. The low price of such pumps means that a farmer can break even on an investment in a treadle pump after only one or two successful seasons of irrigation.
Some factors do limit the utility of treadle pumps. Such pumps can only draw water from shallow underground reservoirs, and may not be suitable for use in areas where groundwater is more deeply buried. Intensive irrigation can also deplete underground water reserves over time, which might further limit the future usefulness of these pumps.