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Technical Briefs and Manuals: English
Human-Powered Handpumps for Water Lifting Introduction This technical brief seeks to outline the main types of hand pumps currently used for domestic and community water supply. The purpose of this Technical Brief is to provide basic features of each and suggest their potential use. A separate technical brief is available discussing human and animal powered water lifting for irrigation. Hand pumps are capable of lifting relatively small amounts of water from depths of up to 100 metres. They are widely used in places where access to other potential water pumping power sources is constrained; where financial resources available for investment, operation and maintenance are limited; and where there is a relatively limited domestic water requirement. Hand pumps are relatively easy to install and simple to operate making them one of the most commonly used water-lifting technologies. This technical brief provides guidance on the key criteria that needs to be taken into account when selecting a hand pump and discusses the applicability of different types to specific local conditions. Selection Criteria for Human Powered Water Lifters Table 1 provides a summary of the technical, financial, economic, institutional and social questions that need to be answered when selecting a hand pump for domestic or communal water supply. Criteria Key Questions Important Points to Note Technical Aspects Lift height and How much water does the community Water consumption is usually estimated at yield need? 15-60 litres/person/day for rural water How high does the lifter have to raise the supply projects. water? The maximum flow capacity of the hand How deep is the groundwater and is it pump should be matched to community likely to fall in future due to over-use? demand. (Pump flow rates are given by the flow-rate/lift-height, or "Q/h", curve, usually supplied by the manufacturer.) The choice of hand pump should anticipate growth in demand and any hence any potential drops in groundwater levels. Water Quality Are there any water quality limitations which Although most pumps are fitted with a Limitations need to be taken into account? strainer/sieve to prevent sand or sediment in the water causing pump damage, some pumps are particularly sensitive to these particles and hence their use with water with a high proportion of solids will lead to frequent breakdowns. Soil Conditions What are the local soil conditions? Where there is very rocky soil a borehole will Can you access water using a hand-dug well usually need to be drilled to reach the or is drilling required? groundwater.
Hand pumps for water lifting Practical Action Criteria Key Questions Important Points to Note Technical Aspects Operators Is the lifter suitable and acceptable to the The choice of pump should take into account people who will operate it? which group of people are tasked with water Is the operation ergonomic (comfortable to collection. In many cases this women and use) and realistic for the group responsible children undertake this activity. It is for water collection? therefore important to determine if average and maximum handle forces required are Are there health and safety considerations, realistic for these two groups. such as dangerous machinery or risk of contamination? Financial and Economic Aspects Capital Cost What is the initial cost of the water lifter? Does the village have sufficient funds or is a loan required? Material and Can the lifter be manufactured using local Manufacturing skills and materials? Costs Operating Costs What is the operating cost of the lifter? Does the village have sufficient manpower to operate the lifter for all the time it is needed? Maintenance What is the cost of maintaining/ repairing Maintenance is an integral part of lifter Costs the lifter? management. For more complicated designs, Are the skills to maintain/ repair the water such as the deep-well pumps, it is important lifter available locally? to carry out preventative maintenance. Serious problems can be avoided by Are spare parts available and affordable? undertaking regular inspections and servicing How often is the lifter likely to need of the mechanical parts. Wear and tear will maintenance and/or repair? be less severe this way and any problems will be solved before they cause major damage. How long will repairs take and what will the villagers do in the meantime? Life expectancy How long is the lifter expected to last before it has to be replaced? How resistant is the lifter to vandalism or abuse? Institutional and Social Aspects Community Is there a community organisation capable The lifter should be suitable for Village Level of overseeing operation, maintenance and Operation and Maintenance (VLOM) or management of the device and the water? Management of Maintenance (VLOMM). This Will the users be instructed how to use and reduces the reliance of villagers upon large look after the device? institutions to sustain the water supply. Table 1 : Checklist for Water Lifting Device Selection Types of Human-Powered Water Lifters Human Powered Water Lifters can be split into two categories, those designed to raise groundwater; and those designed to lift surface water. • Groundwater is water that flows or seeps downward through the earth filling up the spaces between soil, sand and rock to form a saturated zone. The upper surface of this saturated zone is called the “water table.” The “water table” may be just below the surface like a spring or oasis or it may be over 100 metres down. The only way to get access to this water is by digging and/or drilling. • Surface Water is water present in depressions, lakes, rivers, reservoirs, and oceans. 2
Hand pumps for water lifting Practical Action Water lifting for domestic and community water supplies is most commonly related to raising groundwater. This Technical Brief therefore focuses upon groundwater. Water lifting from surface water sources is most often related to irrigation, which is covered in the Technical Brief Human- and Animal-Powered Water Lifters for Irrigation. Open-Well Pumps The simplest and cheapest method of lifting groundwater remains the rope and bucket in a wide, shallow well. Open wells are usually lined with brick, stone or concrete to retain the well walls. This type of well can operate up to a depth of 100 metres, although they rarely exceed 45 metres. The job of drawing water from the well can be made easier by adding a “windlass” (a horizontal cylinder with a winch which can be turned to raise the bucket on a rope) or a “shadouf” (an upright frame with a long pole suspended on top with the bucket hanging from one end and a weight which serves as the counterpoise of a lever at the other.) A shadouf used over a hand-dug well. Source : Edward Stevens (2008) However, when the water table is very deep or where the ground is very hard rock and groundwater needs to be accessed via a borehole, it is usually necessary to install a hand pump to raise the water. Introducing hand pumps also allows the water source to be sealed and reduces the potential for source contamination during water collection. Groundwater hand pumps can be split into two categories, shallow-well and deep-well. 3
This article was added to our catalogue on Sunday 29 October, 2006.
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