Water for Humanity - Appropriate Technology
TREADLE PUMPS
by Steve Herbert
In the year 2000, I had the unforgettable experience of traveling overland in a converted bus with a group of people all the way from Barton, Vermont, to Managua, Nicaragua. Organized by Adam Parke of the organization Monte Verde Cultural Exchange, those who were invited to participate each had a particular expertise to offer, such as organic gardening, sustainable agriculture, appropriate technology, music or theatrical arts. I was invited to participate as the dowser.
Adam Parke demonstrates the treadle pump assisted by his bus-mates. One of the people who had been invited to join us was Carl Bielenberg, an inventor from Marshfield, Vermont, and founder of the Better World Workshop, an organization dedicated to improving the lives of those in developing countries through appropriate technologies. Though Carl could not join the group due to other obligations, he did send along with us three treadle pumps of his design. All along our route, through Mexico, Guatemala, El Salvador, Honduras and Nicaragua, we made stops at various points to give demonstrations, workshops, and arts presentations in our various expertises. This included giving demonstrations of Carl’s treadle pump, and the three models were given to appreciative rural farmers before the return.
A treadle pump, as the name implies, is a manual pump operated by foot peddles, with a peddle and cylinder for each foot. The treadle pump fits the definition of appropriate technology by being a simple technology, easily duplicated or repaired within a developing country with local expertise and readily available materials, and relatively affordable. All treadle pumps are suction pumps, with a capability of drawing water up from a maximum depth of 7.5 meters (or 20 feet). The basic design may have a maximum flow rate of 18 cubic meters per hour, though the flow rate is also dependent on and inversely proportional to the lift height. Water which is drawn into the cylinder exits directly out of the cylinder and into, in the usual case, an irrigation ditch. It is capable of irrigating small areas up to 2,000 to 3,000 square meters.
The proto-type treadle pump was first researched, designed and developed in Bangladesh in the early 1980s. Though the superstructure of the model Carl sent with us was of metal, this early proto-type in Bangladesh was made of wood or bamboo, as it commonly still is in much of the developing world. In these countries the wooden or bamboo superstructure makes the system even more economically feasible. The principle is still the same, however, in spite of what the superstructure is made of. The cylinder on one side is creating suction and discharging as the piston in the opposing cylinder is returning to ready position with check valve closed. This creates a semi-continuous flow.
Adam Parke demonstrates the treadle pump in a community in Nicaragua. A variation of the early Bangladesh design, which is a purely suction pump, is a suction treadle pump which is also a pressure pump. This means that once water is drawn up into the cylinder, the pump has the capability to also force the water up through flexible piping to an irrigation ditch at a higher level. The design of Carl’s model was a basic suction model with some pressure capability. One can read more about the basic design with its variations in the book Carl co-authored with Hugh Allen, How to Make and Use the Treadle Irrigation Pump. We on the bus also had along with us an seed oil press of Carl’s design, intended to help rural farmers more efficiently render the seeds of certain crops into either cooking oil or fuel.
This trip was an adventure that I thrived on for four and a half weeks, until I left my nine compatriots from the bus, plus others who had flown down to meet us in Nicaragua, to take another bus up to Tegucigalpa, Honduras. There I met up with Ken Bannister to repeat a two-week assignment with the US Partners of the Americas and Farmer to Farmer programs initiated last year to offer trainings in dowsing and water resources to rural farmers, and dowse ourselves for environmental refugees from Hurricane Mitch. Eight more trips to Latin America have been accomplished since that trip, with hopefully more to come worldwide.
