If we are to make use of the world's water, we need to understand how water moves naturally.
Water occurs in three forms: as liquid water in oceans, rivers, lakes, in clouds and in the ground; as water vapour (gas) in the air; and as solid water (as snow and ice).
Water moves from one form to another on a continually looping journey that has no beginning and no end. That is why it is called the water cycle.
