Water on Earth

How
much
water
is
on
Earth?
On
Earth
there
is
about

332.5
million
cubic
miles
(mi³)
or
about
1,386
million
cubic
kilometers
(km³)
of
water,
(source:
United
States
Geological
Survey).
The
Earth’s
water
is
circulating
through

oceans,
the
atmosphere,
land,
and
living
organisms.
This
cycle
is
known
as
the
hydrologic
cycle.

What
is
the
Hydrosphere?

In
the
field
of
geography,
the hydrosphere contains
all
of
Earth’s
water.
This
is
the
water
found
in
oceans,
lakes,
rivers,

underground
reservoirs,
ice,
the
atmosphere,
and
within
living
organisms.

Where
is
Water
Found
on
Earth?

Saltwater:
oceans,
seas,
and
bays

Most
of
the
water
found
on
Earth
—about
96.5%—
is
saltwater
and
found
in
oceans,
seas,
and
bays,
totaling
around
321
million
cubic
miles
(~1.34
billion
cubic
kilometers).

Freshwater
sources

Only
about
2.5%
of
Earth’s
total
water
is
freshwater.

• 
  Ice
  caps
  and
  glaciers: Over
  two-thirds
  (about
  68.7%)
  of
  Earth’s
  freshwater
  is
  locked
  in
  ice
  caps,
  glaciers,
  and
  permanent
  snow,
  representing
  roughly
  5.8
  million
  cubic
  miles
  (24
  million
  cubic
  kilometers).
• 
  Groundwater: About
  30.1%
  of
  Earth’s
  freshwater
  exists
  underground,
  stored
  in
  aquifers
  and
  accessible
  via
  wells
  and
  natural
  springs.

Mountains
are
an
important
source
of
freshwater

The

UN
World
Water
Development
Report
2025
notes
that
55%-60%
of
all
freshwater
flows
originate
from
mountains.
Nicknamed
“water
towers”
the
mountain
cryosphere
experiences
more
precipitation
and
lower
evaporation
than
lowland
areas,
resulting
in
a
higher
volume
of
runoff
per
unit
area.

The
“Third
Pole”:
the
Tibetan
Plateau

Most
of
the
freshwater
reserves
are
stored
in
in
ice
and
glaciers
in
the
polar
regions.
After
the
polar
regions
(North
and
South
poles),
the
Earth’s
largest
freshwater
reserve
is
the
Tibetan
Plateau,
home
to
tens
of
thousands
of
glaciers
and
is
known
as
the “Third
Pole.”

Other
freshwater
reservoirs

The
remaining
freshwater—approximately
1.2%—includes:

• 
  Surface
  water: Lakes
  and
  rivers
  hold
  only
  a
  small
  fraction,
  about
  0.26%
  and
  0.006%
  respectively.
• 
  Ground
  ice
  and
  permafrost: About
  0.86%
  is
  trapped
  as
  ground
  ice
  or
  permafrost.
• 
  Atmosphere
  and
  organisms: Approximately
  0.04%
  is
  atmospheric
  moisture,
  while
  a
  very
  small
  amount
  (about
  0.003%)
  is
  contained
  within
  living
  organisms,
  including
  plants
  and
  animals.

Table:
Global
Water
Distribution

The
table
below
shows
estimated
sources
of
water.

Source: Shiklomanov,
1993

Sources
of
Freshwater

This
infographic
from
the
United
Nations
Environmental
Programme
also
adapted
from
Shiklomanov’s
work
shows
the
global
distribution
of
freshwater
sources
from
glaciers
and
ice
caps,
rivers
and
estuaries,
and
groundwater.

Watch:
Earth’s
Water

Read
next:

Groundwater
on
Earth

References

Shiklomanov,
Igor
.
1993.
“World
fresh
water
resources”.
 Peter
H.
Gleick
(editor),
1993,
Water
in
Crisis:
A
Guide
to
the
World’s
Fresh
Water
Resources.

UN
World
Water
Development
Report
2025.
2025.
United
Nations
Educational,
Scientific
and
Cultural
Organization.
DOI:

10.54679/LHPJ5153

The
World’s
Water.
 USGS.

This
article
was
first
published
November
13,
2014
and
has
since
been
updated.

Go to Source
Author: Caitlin Dempsey