Every living organism we know of requires water to survive - it's part of the reason
we look so feverishly for water on other planets across the universe, and consume it consistently
every day here on Earth. So what would happen to your body if you stopped drinking water?
Of course, when we say 'water' we're including all fluids which simply contain water - like
juices, pop, or tea. Much like the desire to breath in oxygen, thirst is a survival
instinct. H20 is the most abundant molecule in the human body making up, on average, 65%
of an adult. As a universal solvent, it carries nutrients and hormones through the body, regulates
body temperature, cushions our joints and even lubricates our eyes. You produce around
1.5 litres of urine every day, with another litre lost from breathing, sweating and...pooping.
So it's essential that the body replaces this liquid.
The thirst centre of the brain is located in the hypothalamus, and is constantly using
sensors in your blood vessels to monitor the amount of sodium and other substances in your
body. For example, if you sweat too much, your blood volume and pressure fall. The brain
then detects this change and creates the urge to drink something, NOW! So what happens if
you are unable to satisfy this thirst?
The initial signs of dehydration are the obvious dry mouth, following which your urine becomes
darker with a stronger odor, as your body attempts to conserve more fluids. The lack
of H20 then begins to affect your brain - you may feel light headed, have a slower response
time and decreased ability to feel pain. In fact, when you're dehydrated, your brain tissue
literally shrinks. In studies observing hydrated vs. dehydrated participants, the same task
required more brain power and oxygen in dehydrated individuals compared to those fully hydrated.
After a day or two with no fluids you'll stop peeing all together, have trouble swallowing,
suffer from muscle spasms and likely experience nausea - after all, your body can survive
without food much longer, and attention to digestion is not a priority at this point.
Eventually, victims may become delirious with severely impaired brain function. Interestingly,
studies looking at elderly patients who suffer from delirium, found that many are simply
suffering from chronic dehydration in the first place. After even more time without
water, the blood stops flowing to your skin, reducing heat loss but increasing your core
body temperature. This can lead to a grey-blueish tinge to your skin. Beyond 3-5 days without
water, and your body will begin to shut down it's organs, and eventually the brain.
Of course, unlike the plentiful oxygen we breath, only 2.5% of all Earth's water is
fresh; most of which is locked up in glaciers, ice caps and underground lakes known as aquifers,
leaving less than 1% available for drinking. And most of this water is actually used to
grow crops; approximately 500 billion litres of freshwater is used daily for agriculture
in the USA alone, with another 500 billion litres to cool electric power plants. And
as our personal drinking sources become increasingly contaminated, over 783 million people on earth
are unable to access clean water.
Scientists around the world are trying to find solutions to this problem - from attempts
to remove salt from ocean water, tap into underground aquifers and creating innovative
water filtration systems. If we look to space, NASA has developed technology for astronauts
to turn their urine into water more pure than what we drink on earth. But we can't just
rely on science and technology - perhaps the solution relies on us as a species to understand
and contribute to this global water crisis.
If you want to help in the mission to end global thirst, join in World Water Day on
March 22nd. There are a lot of really amazing projects out there, like Water.org or even
the awesome UNICEF app which donates 1 day of clean water to child in need, for every
10 minutes you put your phone down. We'll leave links in the description for these and
other great water charities. Small investments really do make a huge difference.
We'll be donating all the proceeds from this video to a water project close to us called
Morocco 5 Villages - so thanks for supporting and watching. And subscribe for more weekly
science videos!