English: A hand-drawn picture of a diy-waterfilter, which can be made in the field with commonly available materials (branches, cloth, sand, charcoal and grass). It can be used to filter (slightly contaminated/polluted) water so that it is safe for drinking. Charcoal can be produced from wood by the indirect (preferred method) and the direct method. The direct method is easiest and requires only wood, an open fire and some plant material to allow the wood to burn up incompletely (see this website for links). The indirect method (which produces far less smoke and is healthier for environment and the person making the coal) is found here and here. The picture has been drawn after a model from Peter Darman's The Survival Handbook.