|
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
|||
|
|||
 |
12: A Primer on Hand-Pumps
Introduction
Groundwater sources of drinking water that are reached by hand-dug or drilled wells fitted with hand-pumps are a common feature of rural water and sanitation projects in the developing world. While there are literally hundreds of different types of hand-pumps produced around the world, they can be generally divided into hand-pumps for shallow and deep wells. Shallow well hand-pumps include suction and direct action models, while deep well hand-pumps are typically lever action hand-pumps.
Shallow Well Hand-Pumps
The suction type hand-pump is probably what most Canadians are familiar with, and works by suction whereby a plunger mechanism is located within the above-ground hand-pump. These pitcher-shaped hand-pumps were commonly used by Canadian family homesteads prior to the widespread adoption of electric pumps. Due to atmospheric pressure limits, a suction type hand-pump has a maximum pumping depth of 6 to 8 metres, so it cannot be used in places where the water table's location exceeds this range. The No. 6 Pump is a good example of a suction type hand-pump model that can be found in use in the developing world.
In contrast, a direct action type hand-pump's plunger mechanism is located in a cylinder below the level of the groundwater table. Rather than having a lever and bearing mechanism, direct action hand-pumps look like oversized T-shaped hand-pumps for automobile tires. When the hand-pump's handle is raised, the plunger lifts a column of water within a tube to the surface. At the same time, water is allowed to enter and refill the tube below the plunger. This type of hand-pump's can lift water from depths of up to 15 metres. Examples of direct-action hand-pumps include the TARA and MALDA models.
Deep Well Hand-Pumps
Deep well hand-pump models such as the rugged India Mark II, Afridev, and U3 are conventional lever action models, and are commonly found in WaterCan projects. While more expensive than suction and direct action hand-pumps, deep well hand-pumps are physically more robust, can serve a larger number of people, and have pumping ranges of 10-45 metres. These models were developed as a result of extensive field-testing by researchers working in the developing world, and have been adopted by many governments as the standard hand-pump technology for medium to deep depth wells. Efforts to standardize hand-pump models in a country also have the benefits of encouraging the development of government and/or private sector spare-parts distribution networks, local manufacturing and servicing capacity, and lower production costs due to the realized scales of economy.
Selecting the Right Hand-Pump
The selection of appropriate hand-pump technology is very important to ensure that a well continues to function properly in the long term. Key factors that influence the hand-pump type selection process include the size and preferences of the population to be served, depth of the groundwater table, and cost-effectiveness and availability of desired models of hand-pumps and spare parts. A cast-iron pump, for example, while suitable for meeting the needs of several households, would not last too long in a typical African village where the hand-pump would be expected to meet the water needs of several hundred inhabitants 12 hours a day throughout the year.
WaterCan and Hand-Pumps
One of the most important things WaterCan looks at when developing projects is that the proposed hand-pump model has Village Level Operation and Maintenance (VLOM) capacity. Unfortunately, in many parts of the developing world, many hand-pumps are broken and inoperable since they relied on servicing by government water departments that are commonly severely under-resourced, or spare parts were not readily available or affordable. In contrast, VLOM-type hand-pump models are designed so that trained villagers – Well Caretakers in Uganda for example – can carry out basic operation and preventative maintenance activities without special tools and equipment
WaterCan also requires that all wells fitted with hand-pumps have a drainage apron that properly disposes of spilt water so that it does not seep back into the ground and contaminate the well shaft and underlying groundwater table. This also prevents the formation of stagnant pools of water that can be breeding areas for disease-causing insects such as malarial mosquitoes. In some communities, the wastewater is diverted to adjacent garden plots where villagers can grow vegetables for sale in local markets.
 |
| Hand-dug well fitted with an Afridev hand-pump, Ethiopia |
 |
| Hand-dug well with U3 hand-pump and drainage apron, Uganda |
 |
| Tara hand-pump with PVC pipes, Malawi |