Red Button Design’s Midomo Water Purifier. Formerly known as ROSS and as seen on BBC 2′s Dragons’ Den!
Potassium permanganate – This is another cheap and easy way to purify water. Potassium permanganate crystals can be bought from any chemist and you need add only about 3 or 4 crystals per litre of water (or until the water stains a light pink) and leave for 30 minutes. Potassium permanganate can also be used as a disinfectant for cleaning wounds, add crystals one by one until water turns purple (approx. 0.01% solution). As an oxidant, potassium permanganate can act as a disinfectant. For example, dilute solutions are used to treat canker sores(ulcers), disinfectant for the hands and treatment for mild pompholyx, dermatitis, and fungal infections of the hands or feet.