The document discusses ways to measure and save water usage while brushing teeth. It describes using a tap, test tube, and stopwatch to measure that 130mL (0.13L) of water runs in 1 second while the tap is on. Extrapolating this, it estimates that 23.4L of water could be wasted if the tap runs for 3 minutes of brushing. The conclusion is that leaving the tap on is wasteful, and advises switching it off while brushing teeth to conserve water.
