The water we drink and use was running short. We all have to learn what to stop wasting water.
One of the step that we should take is to find ways of reusing it. Today in the most large cities, fresh water is used only once and then it runs in waste system. But that is possible to pipe the used water to a purifying factory, there the used water can be treated with chemical materials by the workers so that it can reused. But even if every large city purified and reused it's water, we still would have enough water.