This is called white charcoal and it is produced in Japan.
This is food grade charcoal that is used for filtering water and air,
for odor absorption and for cooking.
This method of filtration was widely used by the ancient Japanese and Chinese.
The ancients believed that it ‘sweetened’ the water especially for a superior brew of tea.
Charcoal is very porous and therefore it can absorb and retain impurities.
It readily absorbs odors and other foreign impurities from water.
It is also rich in minerals and imparts these minerals as it filters and enriches the water.
Method of using for filtering water for tea is using a 2in x 2in piece charcoal.
Rinse the piece before adding it into a kettle with 8 cups of water.
Boil the water and use per tea infusion.
A 2 in x 2 in piece will last for 3 weeks.