because it just does
just about 95% of the Earth is water
Mostly
Because the water cycle takes place. It ensures a continuous supply of fresh water on Earth.
We are using our fresh water faster than the ground supply is replenished. Also, earth's water is threatened by pollution.
Roughly 2.5% of Earth's total water supply is usable fresh water, with the majority of it locked up in glaciers, ice caps, and groundwater.
"The Antarctic Icecap is the largest supply of fresh water, representing nearly 2% of the world's total of fresh and salt water." Source: http://www.infoplease.com/ipa/A0004674.html
earth's water cycle gives us fresh water. we use this fresh water for our daily consumption. when this water cycle is in danger ,our fresh water source also comes in danger. thus if any disturbances occur in the earth's water cycle ,these disturbances directly or indirectly affect our water supply. for example if an area's water supply depends upon a river's fresh water and if due to acid rain the water of that river gets contaminated then the water supply becomes contaminated and cannot be used.
The Antarctic Icecap contains about 70% of the world's fresh water supply in the form of ice. This makes it the largest reserve of fresh water on Earth.
The reason why fresh water is considered a limited resource is because the large majority of water on earth is saltwater. 97 percent of the earth's water supply is saltwater and only 2.5 percent is fresh water, some of which is snow and ice.
precipitation A+
It is theoretically possible for humans to deplete all the fresh water on Earth if it is not managed sustainably. However, proper water conservation and management practices can help ensure a continuous supply of fresh water for current and future generations.
because most of the earths water is salt water and there us only 2.5% of fresh water on the earth =D