Water

Turn on the tap and the water flows. Does anyone know where the water goes?

Turn on the tap and the water comes. Does anyone know where the water's from?

Water is clean and water is cool, living in rivers and raining in pools.

Yet water can trickle and wells can dry up till there's nothing left to fill the cup.

Today there is water when we turn the tap on. But what will we do when the water is gone?