Biosand Filters

One thing the water project has begun working on recently is the construction of some biosand filters. A biosand filter is a simple, small scale filter for cleaning water. There are a number of ways to make the filters, but we are making them using old aviation fuel drums. AIM AIR, the missionary flight service that brings the missionaries in and out of Doro leaves a stock of drums full of jet fuel by our airstrip, so that the planes can refuel when they land here. The empty drums get piled up in a corner of our compound, and we can purchase them from AIM AIR for a small fee. They are ideal for making the sand filters.

To construct a sand filter, we put a small layer of gravel at the bottom of the filter, and a thick layer of sand on top of the gravel. A flexible hose is placed inside the gravel layer and fed to a tap on the outside of the barrel. The sand and gravel has to be cleaned thoroughly before placing it inside the drum. To use the completed filter, you simply fill the drum with water. The water percolates down through the sand and becomes clean. The way the filter really works is that over time a layer of bacteria forms on top of the sand. This layer of good bacteria actually works to purify the water, as it eats the harmful bacteria in the water as it filters down through the sand. These filters have shown to be very effective in cleaning water. One filter is sufficient to provide clean water for several families in a community.

So far we have constructed one filter which we have located down near the Doro health clinic. Our hope is to construct some more and place them in villages that have access to a source of water, but not a clean source. It could be a dirty borehole or river water. They can then take the water that they have access to and put it in the filter to clean it and make it good to drink.

This is just one of several ways that we are trying to help people in the villages have access to clean water. It is such a neat experience to not only learn about different ways of providing clean water (such as the construction of the filters), but also to be able to help the people with such an important need. Stay tuned for more updates on other ways we are seeking to provide clean water. For now I will leave you with some pictures of the process of making a biosand filter.

Here are the barrels that we are turning into sand filters.

Abel starts getting a barrel ready.

We cut out the top of the barrel and now John is filing the sharp edges.

This is what happens after a hard day's work!

Joseph is preparing the hose to go into the barrel. He is drilling holes in the hose so the water can pass into it.

Abel washing the sand.

Putting the sand into the barrel. Notice the tap is already attached.

Joseph and I with the finished sand filter.