Although it may seem improbable, the charcoal wood filter is the oldest method of water purification. It was already used by the Japanese in ancient times, when no other means for crystal-clear, perfectly transparent water were available. Binchotan (Japanese binchō-tan), from which the presented Black+Bum filters are made, also known as white charcoal, softens water and absorbs any undesirable odours from it, including the smell of chlorine. The filter was developed for Black+Bum carafes, but can be used in any type of bottle or jug to filter tap water and thus contribute to reducing the use of plastic bottles. The water becomes better after just one hour of putting the filter in, but the best effect is achieved after eight hours. Simply place the filter in the water and wait for it to work wonders!