Not all gadgets have to be of the man made kind. Scientists in the UK have developed a system to clean water by the use of plants. The system is designed to be used with water in a house that has already been used once. The used water, perhaps from washing dishes, is then sent to the trough of specially selected plants. There the plants suck up the impurities and presto, you have clean water.
There is of course the question of practicality and how many plants it takes to clean ‘x’ amount of water. In either case the inventors hope to commercially market the invention some time in 2006.