Pure Home Water, Ghana manufactures and distributes AfriClay Filters in an effort to bring clean water to 1 million people. So far they have delivered filters to provide 100,000 people clean water.
The process is simple. Water is placed in a clay filter and gravity pulls the water through the pores left in the clay during firing.
Sediment and bacteria are filtered out in several ways:
- Physical straining: the particles are too large to fit through the pores in the clay
- Sedimentation or adsorption: particles come to rest on or stick to the clay
- Inertia: friction in the pores keeps the particles from passing through
Bacteria are also killed by a coating of colloidal silver (a disinfectant), which we apply to all filters that pass our quality control tests. While sediment and bacteria are filtered out, the molecules of water are small enough to pass through the pores in the clay.
The filters are sold to those who will use them. The effort has shown a willingness to pay by villagers in remote Northern Ghana (those earning < US$1/day). I imagine (I am just guessing) the prices are subsidized; in the last decade more (most?) appropriate technology solutions will have those benefiting pay something for the benefits they receive.
My nephews are working on a similar effort in India, using bio sand filters, I plan to post more on that later. There is current a campaign to help fund the delivery of water filters to Indian villages.