posted by Lenneke Knoop
May 25, 2012
This stone is used by the community in Witu, Kenya to clean their drinking water. People in Witu stir this stone in the water. Small particles of the stone fall off and sink to the bottom. In this process other solids that are in the water attach to the stone particles and sink to the bottom as well – leaving behind clear drinking water.
The stirring process cannot take too long as this stone will leave a bitter taste to the water and can even make the water poisonous when too much stone particles are dissolved. This stone costs around 10 Ksh (0.10 USD).