The total water content in the earth remains nearly constant.
Explanation:
The amount of water on earth is nearly same as the amount of water that was on earth in Mesozoic era.
Plants and animals use water as a raw material in their growth, but that water is eventually returned to earth.
When the UV light breaks the water molecules in higher atmosphere, some water is lost.But it is compensated by the water that enters the earth through meteors and comets.
The water content is not constant but through the series of biochemical reactions,the water level is nearly the same.
