It uses the same principle as your Brita filter to purify water, but Black+Blum's Eau Good bottle does it with way more style using a stick of charcoal that's always visible through the bottle's lovely curves.
Known as Binchotan, the black stick is a type of carbon made from tree branches, which the Japanese have been using to soften and purify water for centuries. It can even reduce the amount of chlorine in your H2O, though the passive process does require quite a few hours to work its magic. So it's recommended you leave the Eau Good bottle sitting overnight before drinking. We recommend staring at the bottle while it works.
To prevent the charcoal from floating to the surface, the £20 plastic bottle has been designed with a slight bulge on the side, keeping the £4 Binchotan stick submerged at all times. It's promised to work for up to 6 months before it needs to be replaced, while a quick 10 minute boil at the 3 month mark will help ensure its effectiveness. And when it does stop working, you can of course just toss the charcoal stick in your garden, where mother nature will recycle it for you. [Black+Blum via bookofjoe]