Tuesday, May 5, 2009

Simplicity: Water Delivered by Gravity

In remote communities, there are only a few ways to get water; and often there are even fewer ways to get clean water. For the poorest, the simplest option is often the only one: fetching water from a stream. This is usually a less-than ideal solution because streams can easily be polluted by others living up-stream. The streams are used for washing clothes, feeding animals, and open defacation. Obviously this creates all sorts of problems when trying to use it as a potable water source. A second option is well water - this is often safe, and for a while a plentiful source. However, it is limited in the number of people it can serve because people must walk to the well. Therefore, many wells are needed when serving sparsely populated areas.

A third option is called gravity water distribution, and it works like this: a source is identified on top of a hill, protected, and then pipes are built out to resevoirs as far as 10km away. This has the advantage of providing clean water to a large number of people distributed over a wide area. It is also simple - it doesn't require any mechanical equipment, and therefore does not need electricity to operate. It is also very easy to maintain. The only drawback is the initial expertise required to develop the system, and the possibility that the source may run out if used too quickly. In general however, it is a system with many advantages and few drawbacks.


  1. I love learning from dr. Densmore! But can you show me how to make a battery using a potato?!

  2. Thanks, Alex. We miss you. World Vision magazine online has a good story about a long-term irrigation project in Kenya that might interest you. --Walt Hearn