Bomba De Ariete

4. WATER-LIFTING DEVICES

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4. Water-lifting devices

4.1 Introduction
Water-lifting devices are used to lift water to a height that allows users easy access to water. Lifting devices can be used to raise groundwater, rainwater stored in an underground reservoir, and river water. Communities should be able to choose from a range of water-lifting devices, and each option should bepresented with its advantages, disadvantages and implications. For example, water lifting involves additional O&M activities and potential problems, compared to gravity systems, and the latter are often preferred if they are available and applicable to the situation. The following water-lifting devices are described in this manual: — — — — — — — — — — — rope and bucket (loose through a pulley, or on awindlass); bucket pump; rope pump; suction plunger handpump; direct action pump; deep-well piston pump; deep-well diaphragm pump; centrifugal pump; electrical submersible pump; axial flow pump; hydraulic ram pump.

There are other water-lifting devices that are not described in this manual, such as the progressing cavities pump, the manual diaphragm suction pump, the treadle pump and the chainpump. Other devices, such as the air-lift pump, are not included because they are not applicable to drinking-water supply systems.

4.2 Rope and bucket1
4.2.1 The technology
This device is mainly used with hand-dug wells. A bucket on a rope is lowered into the water. When the bucket hits the water it dips and fills, and is pulled up with the rope. The rope may be held by hand, run through apulley, or wound on a windlass. Sometimes, animal traction is used in combination with a pulley. Improved systems use a rope through a pulley, and two buckets – one on each end of the rope. For water less than 10 m deep, a windlass with a hose running from the bottom of the bucket to a spout at the side of the well can be used. However, the hygiene of this system is poorer, even if the well isprotected. Initial cost: From US$ 6 for a plastic bucket and 5 m of rope, to US$ 150 with a windlass, hose and closed superstructure, in Liberia (Milkov, 1987).
1

Morgan (1990).

LINKING TECHNOLOGY CHOICE WITH OPERATION AND MAINTENANCE

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Range of depth: 0–15 m (or more sometimes). Yield: 0.25 litres/s at 10 m. Area of use: All over the world.

4.2.2 Main O&M activities
The bucket islowered and raised by playing out and pulling in the rope, or by rotating the windlass. Care must be taken to prevent the rope or bucket from becoming soiled. Preventive maintenance consists of greasing the bearings of the windlass or pulley. Small repairs are limited to patching Figure 4.2 Rope-and-bucket lifting device. holes in the bucket and hose, reconnecting the hinge of the bucket, and fixingthe windlass bearings or handle. All small repairs can be done by local people, and with tools and materials available in the community or area. Major repairs and replacements mainly consist of replacing the bucket, hose, rope, or part or all of the windlass. Woven nylon ropes may last for two years, but twined nylon or sisal ropes last only a few months. A good-quality hose may last for over twoyears, and most buckets last a year (depending on the material and quality). When people use their own rope and bucket, no extra organization is required. For community wells, a community committee usually organizes the maintenance and cleaning of the well, maintenance of the windlass, etc. Most repairs can be paid with ad hoc fund-raising. For maintenance of the well, see Fact Sheet 3.5.

4.2.3Actors and their roles
Actors Users. Caretaker. Water committee. Local artisan. Shopkeeper/trader. External support. Roles Lower and lift the bucket, keep the site clean, warn when the system malfunctions. Keep the site clean, carry out small repairs. Organize cleaning of the well, collect fees. Repair the bucket, windlass, well cover, etc. Sell the rope, buckets, etc. Check the water quality,...