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Bio-Sand Water Filter
What is it?
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A permanent, affordable, easy to maintain, water filter which is produced from locally available materials.
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The filter, when constructed appropriately, is recognized globally as an effective means of treating water at the household level.
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A concrete container about 1 meter in height and roughly 1/3 meter in diameter, which holds layers of sand and gravel.
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When used most effectively it can provide 6 liters of clean drinking water per hour.
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Source water is poured into the top of the filter, through a diffuser to protect the surface of the sand and travels through the sand layer, the small gravel layer, the large gravel layer and up the plastic tubing encased in the concrete and out of the filter, for the user to collect in a clean water container.
How it's made from start to finish
Scroll through the images and hover over them to learn more about what is happening
How it works:
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Using a combination of biological and mechanical processes, the microbes which need to be removed are trapped near the top of the sand layer, forming a biological layer. This biological layer matures over one to four weeks, depending on the volume of water put through the filter and the amount of nutrients and micro-organisms in the water.
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Viruses are most likely absorbed or become attached to the sand grains and after some time die or are changed by the other microbes in the filter. Sediment, cysts, and worms are removed from the water by becoming trapped in the spaces between the sand grains.
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There is a layer of water which is maintained above the biological layer at all times to protect it and allow for the intermittent use of this filter.