Treadle pumps

 A treadle pump is a human-powered pump designed to lift water from a depth of seven meters or less, from any water source. Pumping is activated by stepping up and down on treadles which drive pistons, creating cylinder suction that draws groundwater to the surface. Treadle pumps have primarily being developed for pumping water for irrigation. However, other uses include pumping potable water for domestic and livestock consumption.

Treadle pumps help farmers to minimize dependence on rain-fed irrigation by giving them the capacity to grow crops all round the year. In addition, it helps farmers maximize return on their small plots of land. Pump prices, including installation, range from US$50 – $120 based on the different costs of labour and materials in each country.

1. Key Technical Characteristics and Basic Principles of Operation of the Treadle Pumps

The most important innovation of the treadle pump is the change from using arms and hands for pumping to feet and legs. This is because the most powerful muscles are the legs and back muscles compared to muscles in the arms (Fraenkel, 1995).

A treadle pump comprises of a cylinder fitted with a piston and some means of pushing the piston up and down. A pipe connects the pump to the water source and at the end of this pipe is a non-return valve that allows water to enter the pipe and stops it from flowing back to the source.

The piston and cylinder must have a close fit so that when the piston is raised, it creates a vacuum in the cylinder and water is sucked into the pump. When the piston is pushed down, the water is pushed through a small valve in the piston to fill up the space above it. When the piston is raised again, it lifts this water until it pours out over the rim of the cylinder and into the irrigation channel or tank. At the same time, more water is drawn into the space below the piston. The downward stroke of the piston once again pushes water through the small valve into the space above the piston and the process is repeated all over again.

Two cylinders are used positioned side by side and a chain or rope, which passes over a pulley or a rocker bar, connects the two pistons so that when one piston is being pushed down, the other is coming up. Each piston is connected to a treadle. The operator stands on the treadle and presses them up and down in a rhythmic motion; just the same way you cycle a bicycle. This rhythmic method of driving the pump has gained wide acceptance among poor farmers and seems to be preferable to any mechanism that requires only one foot or arms and hands. (Balla, 2004).

Two pumps have been developed from this concept. The first was the suction pump to lift water from a shallow well and discharge it over a spout into a canal for gravity irrigation. This was developed in Bangladesh where farmers needed to lift large quantities of water through shallow lifts of 1-2 metres (Balla, 2004). The second development was the pressure pump. This works on exactly the same principles as the suction pump but the delivery end was modified so that water could be fed into a pipe under pressure for sprinklers or hose pipes. The pressure pumps are used when water sources are deep (more than 4 metres) and there is need to deliver water under pressure to sprinklers, drippers or to a head tank. This requirement may also be the result of irrigating undulating or steeply slopping land.

2. Benefits and Best Practices of Treadle Pumps

• Reduced work time compared with bucket irrigation;
• Higher efficiency of the pump reduces frequency of irrigation to two or three times a week;
• Treadle pump irrigation Increases land area under irrigation and can also increase crop quality;
• Additional and new crops can be grown in each season;
• Increased number of growing cycles as crops are able to grow faster with irrigation; and,
• Improved farm incomes due to increased productivity.

3. Common Problems and Response options

• The cost of treadle pumps is still beyond the reach of many low-income communal farmers who may require some form of credit scheme to overcome the high-up-front cost.
• Pumps are mostly managed by women. However, operating a treadle pump requires elevation of operator above the ground. In certain parts of the developing world, women do not feel comfortable standing on the pumps for long periods. They feel exposed and consider it undignified. However, with additional income from increased productivity, women can employ young men to carryout pumping. Treadle pumps can also be re-designed to reduce the required elevation.
• Unlike other pumps (e.g. wind pumps), treadle pumps appear to have a limited suction head of up to 7 meters and are best used in places with high underground water tables.

4. What to Consider When Installing these Technologies on a Small Scale

• Carry out an assessment of the minimum water requirement per day and depth of the well (if applicable) to determine the size of the pump to suit the water requirements and ensure a reliable and durable source of water ( >1 litre/second per pump) 
• Make sure that there is water source within 6metres from the ground surface or locate the pump in locations where the source of water (well or stream) is close to the area to be irrigated.
• Ensure that adequate land is available for garden expansion and that there is a market for the increased production arising from irrigation by treadle pump
• Since the pump utilizes human energy, ready availability of labour is crucial.

5. Case Study of ApproTEC Treadle Pumps, Kenya

In Africa, Kenya is one of the countries where treadle pumps are manufactured and appear to have become popular among low-income farmers with small vegetable gardens from which they sell the produce in markets. The use of treadle pumps has been ongoing in Kenya since 1991 when the first version was introduced in both rural and urban areas and generated a mix of results from users, manufacturers, promoters and retailers.

The experience in Kenya shows that treadle pumps are purchased mainly through savings made by users. Other important sources of capital include selling of crops, livestock and retirement benefits. The majority of the treadle pump owners came to learn of these pumps by word of mouth and through live demonstrations of the technology and this attracted most of the people to purchase pumps. While males own 84% of the treadle pumps, women manage nearly three quarters of these pumps, which are mainly used for irrigating crops and to some extent in supplying water for household use and animals.

A reliable source of water to run the pump is a pre-requisite for a successful use of the pumps. During the 1999 survey by the Monitoring Department of ApproTEC, most of the pumps had been in use for over 8 months drawing water mainly from streams and wells of average depth of 14 feet (approximately 4,3 metres). In rural areas, digging a well cost Ksh. 130 per feet (approximately Euro 1,26). At the time of survey, 91% of the pumps had been active and had been used at least once. The reason for inactive pumps was attributed to increased depth of the water level in the well making the use of pumps impossible.

However, poor farmers face several challenges in the day-to-day operation with the pumps. These include mechanical problems, seasonal water sources for those using dams and wells, limited suction head of many wells whose depth is beyond reach of many pumps. In some areas, especially Machakos, Makueni and Kitui, there is a major problem of salty water that corrodes pumps. Sloppy lands in Central part of Kenya inhibit use of pumps. Farmers also complained of lack of knowledge of appropriate irrigation methods and were concerned that the tread pumps irrigate limited areas compared to the motorized ones.

Most of the pumps are used on an average of approximately 3 hours per day with more time (4hrs) being spent to irrigate farms in Western Kenya than Central province. Areas under irrigation increased amongst users by 700% from an average of 0.03ha to 0.24ha in 1999 to 0.59 ha in 2004. Each pump sold is used by approximately 2 households as a third of the pumps are lent out to neighbours for use at no cost.

Farmers are engaged in producing high value crops such as tomatoes, kales and cabbages. There are those who plant french beans, cut flowers, passion fruits, green maize and onions. Potatoes, cowpeas, carrots, tea nursery, coffee, coriander, watermelon, spinach, sugar snaps and okra are also irrigated by a number of farmers. The increased crop intensity means that pump users are moving away from traditional crops that were mainly for subsistence and increasing the volume of cash crops. The number of crop cycles has also increased as a result of irrigation from 1.2-crop cycle before irrigation to an average of 2.3 for those not involved in irrigation before. One advantage associated with increased number of crop cycles was timing of cropping so as to have the crops when they fetch higher prices from the market.

Treadle pumps have increased incomes for poor families, created employment for operators and owners, made irrigation easy, provided food for poor families and created opportunities to invest in other income generating activities.

by AFREPREN

 
References and Links

 
http://www.fao.org/docrep/005/x8293e/x8293e00.htm
http://www.ideorg.org/OurTechnologies/TreadlePump.aspx
http://www.its.caltech.edu/~e105/readings/cases/IDEtreadle.pdf
http://skipumps.com/treadle.htm
http://www.iwmi.cgiar.org/publications/IWMI_Research_Reports/PDF/Pub117/RR117.pdf
www.kickstart.org
http://kickstart.org/documents/HBSCS2003.pdf
Balla, P. (2004). Potential Contribution of Non-Electrical Renewable Energy Technologies (RETs) in Poverty reduction in Kenya. AFREPREN/FWD Secretariat, Nairobi
Fraenkel, P (1995). Water-Pumping Devices: A handbook for users and choosers. FAO and IT Publications, London, United Kingdom.

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