The Drawbacks of Rope Pump
Like most things in life, the rope pump is not a package of unmitigated joy and happiness. There are a few drawbacks. These include depth limitations and possible water contamination.
While the rope pump is effective for shallow wells, it is less effective for deeper wells. Unfortunately, it is not easy to predict how deep a well can be in which a rope pump will work.
The unpredictability arises from the use of local materials with no universal standards. Both the diameter and thickness of the valves, for example, affect how deep a well may be (on which to put a rope pump). Because inner tubes and leather come in several thicknesses, and because the valves are cut by hand by local artisans, they are not uniform. If the valve is too thin and flexible, it bends and releases water down to the valve below it on the rope.
As wells are more deep, the water weighing on the bottom valve may be so heavy that it all leaks down before it can be brought to the top of the well. Similarly, even if it is not too flexible, it may not be cut to precisely the diameter of the inside of the pipe, and water will again leak to the valve below. This problem, too, increases with the depth of the well. If the valve is cut to fit too tightly against the inside of the pipe, in contrast, it might more effectively bring the water up the pipe, but that might also add to the difficulty of cranking the wheel at the top. At some point the wheel will be too difficult to turn by hand. This problem, too, increases with the depth of the well.
Since these are unpredictable variables, it is not yet possible to state what is the maximum depth of well on which a rope pump will be effective. Perhaps it is 35-45 metres.
Another drawback is a potential for well contamination. The rope pump described above does not indicate that the well should be covered. There is a tendency for local people to omit covering the well, because that takes time, money, effort and desire (based on hygiene knowledge). If the well is uncovered, little animals can get into it and defecate or die or both. Human wastes and parasites can even find their way into the well if hands are not clean when the wheel is cranked.
A good well cover will allow the pipe to come up above it, before diverting the water pulled up by the upcoming rope to a container. A simple hole in the cover for the down going rope may be satisfactory. It will certainly be improved by installing a short piece of pipe, a little wider than the main pipe, above the cover, so that the valves can easily go into it, along with the rope, back down into the well.
When the residents of the community are not so concerned about hygiene (the norm, unfortunately, rather than the exception), and short on resources, they may be more tempted to omit the cover, thus allowing an increased potential for well contamination.
Appropriate training and effective hygiene public awareness may decrease the effects of these drawbacks.
While these are recognized drawbacks to using a rope pump, they are not major problems. Experts with vested interests in using hand pumps, however, will exaggerate them, and omit telling you that the costs of dealing with such minor drawbacks are far lower than the costs of using hand pumps.
