Did you know that one gram of bamboo charcoal has the surface area of up to three tennis courts? Charcoal is porous, meaning it can can absorb impurities - a bit like a sponge. This bamboo charcoal is carefully made in Japanese clay kilns.
To use it as a water filter, wash your charcoal in running water and boil it for 10 minutes to sterilise it. Let it dry. Place it in a litre jug and fill the jug with tap water. Leave it for 8 hours to complete the filtration process. The charcoal will absorb chlorine and chloramines in your water - it can even absorb heavy metals, pesticides, surfactants and hormone-disruptors. Once the time is up, your water will be ready to drink and will even have some added minerals including potassium and magnesium from the charcoal. You can reuse your charcoal filter for two months, boiling it once a week to keep it sterile.
After the two months, you can use your charcoal around the house. It can be kept in a drawer to keep it dry or in an area of your house prone to damp (it inhibits mould), places where you keep your food (it keeps food fresh) or smelly places like the fridge or the loo (it absorbs odours) for 6-12 months. At the very end of its life, crush the charcoal and bury it in the soil - it'll help aerate the soil and improve water retention!