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Water Facts

Water is essential for the survival of all known forms of life.

Clean, fresh drinking water is essential to human and other life.

Water covers 70% of the Earth's surface.

The human body is anywhere from 50% to 80% water
depending on body size.

4 to 7 glasses of water - almost 1 to 2 litres daily
is the minimum to maintain proper hydration.

The single largest freshwater resource suitable for drinking is
Lake Baikal in Siberia.

The Great Lakes comprise 20% of the worlds' fresh water

Water moves continually through a cycle of
evaporation, precipitation, and runoff, usually reaching the sea.

Winds carry water vapor over land at the same rate as runoff into
the sea, so it stays balanced

Freshwater refers to naturally occurring water on the surface
such as bogs, ponds, lakes, rivers and streams and
underground in aquifers and underground rivers.

Freshwater is characterised by having
low concentrations of dissolved salts.

Scientifically, freshwater habitats are divided into

lentic systems
which are the stillwaters including ponds, swamps and mires ,

lotic systems
which are running water and groundwater which flows in rocks and
aquifers.

There is in addition a zone which bridges between
groundwater and lotic systems which is the hyporheic zone.

the hyporheic zone underlies many larger rivers
and can contain substantially more water
than is seen in the open channel.

It may also be in direct contact with the underlying groundwater.

Courtesy of Wikipedia

Where is Earth's water located and in what forms does it exist?

You can see how water is distributed by viewing these bar charts.

The left-side bar shows where the water on Earth exists;

about 97 percent of all water is in the oceans.

The middle bar shows the distribution of that three percent of all
Earth's water that is freshwater.

The majority, about 69 percent, is locked up in glaciers and icecaps,
mainly in Greenland and Antarctica.

You might be surprised that of the remaining freshwater, almost all of
it is below your feet, as ground water.

No matter where on Earth you are standing, chances are that, at some
depth, the ground below you is saturated with water.

Of all the freshwater on Earth, only about 0.3 percent
is contained in rivers and lakes,

yet rivers and lakes are not only the water we are most familiar with,

it is also where most of the water we use in our everyday lives exists.

http://ga.water.usgs.gov/edu/earthwherewater.html