* Providing enough water for everyone in the world is one of the biggest tasks we have in the future.
* The numbers of people who live in areas that have drought is getting bigger and when the rains fail they might starve.
* In any case, cleaning and moving water is expensive and so it makes sense to use water wisely. We can all do this by not running taps for too long, using less to flush toilets and so on. But this is only worthwhile if water companies play their part and cut out leaks.