The Woody charcoal water filter is made from binchotan charcoal, one of the strongest natural filtering materials. It is made of 97% pure carbon this allow Woody to absorb toxins, lead, mercury, cadmium, copper and chlorine from tap water. In return, it frees calcium, potassium and magnesium into your water. The Woody charcoal filter works best when left in a glass carafe for 8 hours, but its effect is already noticeable after one hour.