Biodegradable bamboo charcoal water filters These water filters have everything: biodegradable, reusable, compostable and zero Waste. Made From Natural Bamboo and suitable for vegans.  INSTRUCTIONS  Wash in running water to remove powder (do not use detergent). Boil for 10 mins in a pan of water to sterilise & allow to cool and dry. Place in a jug and fill with tap water (charcoal may float when new but it will tend to sink after a week or so of use). Leave for 8 hours or more for best results. You can leave it in the fridge to chill if you like. It's then ready to drink. Re-sterilise once a week by repeating step 2. Replace with new charcoal after 2 months approx.