This active charcoal is used to filter water by absorbing impurities (such as chlorine), and add minerals (such as calcium). It has been used by the Japanese for over 500 years and will make your tap water taste great. This range was created to encourage people to stop buying expensive bottled water and adding to the continuing single-use plastic global environmental problem. 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, and they are then recyclable for other uses around the home e.g. if you break it up and put it in your house plants, it will add nutrients to the soil that will help the plant to grow.