Binchotan active charcoal is used to filter water by absorbing impurities such as chlorine, and adding minerals such as calcium. These charcoal refills are pre-washed and vacuum sealed so they are ready for immediate use. Simply drop the charcoal into your water, we recommend one stick per litre, then leave for 1 hour and enjoy your filtered water. Each charcoal will last for 6 months as a water filter. They are then recyclable for other uses around the home, such as plant fertilizer.