The Kishu Binchotan Charcoal Refill is a single stick of Japanese white charcoal, approximately 18cm long and 1.5cm in diameter, for filtering a bottle of tap water. Made from hard Japanese Holm oak, it turns ordinary tap water into a daily supply of filtered, mineral rich water. Allow roughly one month of mineralising capacity and three months of purifying capacity per stick.

Water moving through the cavities in binchotan is doing much what water does underground on the way to a spring, picking up minerals and shedding what it does not need. Added chlorine drops by as much as 75 per cent, while potassium and magnesium go the other way.

This is the replacement stick for anyone already using a binchotan bottle. Worth keeping one in the cupboard, because the gap between fresh charcoal and spent charcoal is obvious once your palate has adjusted to the difference.