I’m dying of thirst. Can I start drinking seawater?

May 29, 2012 · Castaway Survival

Before, when I saw a castaway having a bad time, literally dying for a drink but surrounded by seawater, the message in films was always ‘whatever happens, never start drinking seawater. If you were to do so, perhaps you’d feel a bit better, a bit less thirsty, but it wouldn’t be long before you were dead. In films nobody explained the reason for this warning, but neither did anyone doubt it was true.

Let’s explain why.

Imagine that you’re drifting on a piece of wood in the middle of the ocean. Your mouth is dry. You are totally surrounded by seawater. The sea is the most amazing blue… Sometimes the sea seems to be a greenish colour and that’s because of the tiny bits of seaweed which make up the phytoplankton which is also green, as are all plants that perform photosynthesis… But then you can’t stand it anymore, you give in and start drinking sea water.

 

Seawater makes up 97.3 % of the Earth’s water so only 2.7% is fresh water. You convince yourself that there can’t be so much poison in the world, but there is.

Our kidneys are the filters that separate the waste material in the blood and this waste is then stored in the form of urine in the bladder, ready to be expulsed from the body. A kidney cannot make urine from a concentration of salts of more than 2%. Seawater is made up of approximately 3% salt, so if we drink it to quench our thirst the kidneys have to use existing water from our body in order to dilute the extra salt, which in turn makes us feel even thirstier.

This is due to the osmosis process where the kidneys can only generate urine which is less salty than the water we drink. Consequently, the body tends to urinate more to be able to eliminate the excess of salt but instead of elimination, the result is the formation of more salt as the urine obtained is always less salty than the original. The body would have to expulse more liquid than the amount drunk, which is impossible and that’s why the effect of drinking water from the sea is, paradoxically, dehydration.

Seawater contains three percent salt. This means that if we drink a litre our kidneys would need at least one and a half litres of fresh water to dilute all the salt, so this means that they would be forced to extract an extra half a litre from our body.

WHICH IS BEST, DIE OF THIRST OR DRINK SEAWATER?

This is the interesting part. Should you find yourself at high sea and it’s been a few days since it last rained, it would be possible to drink small doses of seawater, just one spoon of seawater at 20 minute intervals, drinking very slowly and letting the saliva in your mouth reduce the saline in the water you have swallowed. A man named Alain Bombard demonstrated this a few decades ago in an experiment called “Voluntary Castaway”.

 

Do you think any of your friends would enjoy reading this article? If yes, click on the buttons just here, below, to share it with them. Thanks for your support!

Follow Us!

{ 47 comments… read them below or add one }

MaRvic C. BriÑan September 15, 2012 at 1:17 pm

nyc one!

Reply

Peter Jhon Campaner September 24, 2012 at 8:42 am

ahmp

Reply

Somebody April 19, 2013 at 12:00 pm

its Fab!!!!!!

Reply

Somebody April 19, 2013 at 12:02 pm

its nice! it helped me in my project. ThanQ very very very very very very very very very mmmmmmmmmuuuuuuuucccccccchhhhhhhhh !!!!!!!!!!!!!!!

Reply

Alvaro Cerezo April 29, 2013 at 9:44 pm

You are welcome!

Reply

Wiki June 13, 2013 at 9:15 pm
Andrew Whittaker June 4, 2014 at 11:53 pm

Something everyone knew. but either way…interesting/…

Reply

Alvaro Cerezo October 9, 2014 at 3:12 pm

Thanks! :)

Reply

Amardeep Singh July 11, 2014 at 4:17 pm

NICE ARTICLE

Reply

Alvaro Cerezo October 9, 2014 at 3:13 pm

Thanks! :D

Reply

Chee Woon July 22, 2014 at 4:45 pm

Good article!!

Reply

Alvaro Cerezo October 9, 2014 at 3:13 pm

Thanks :D

Reply

Raly Todorova August 3, 2014 at 10:15 am

So if you get shipwrecked in the middle of the Black Sea, where the salinity is ~1.7%, drinking the water won't have you dehydrated?

Reply

Alvaro Cerezo April 19, 2015 at 1:26 pm

Yes. In the Black Sea you will probably have a little more chances to survive :)

Reply

Mohammad Bilawal August 6, 2014 at 3:07 am

We can drink sea water from the bottom of the sea if we are a little further and we can store it in something,

Reply

Alvaro Docastaway August 29, 2014 at 8:00 pm

Thanks Brett :)

Reply

Alvaro Docastaway August 29, 2014 at 8:00 pm

Thanks Amardeep :)

Reply

Alvaro Docastaway August 29, 2014 at 8:00 pm

Thanks Chee :)

Reply

Alvaro Docastaway August 29, 2014 at 8:01 pm

Probably yes. Even more dehydrated if you get adrift in the dead sea :)

Reply

Alvaro Docastaway August 29, 2014 at 8:03 pm

Sorry Mohammad. I could understand what you said.

Reply

Mohammad Bilawal August 29, 2014 at 9:52 pm

Alvaro Docastaway You can drink the sea water if you go above the sea level like a little further from the starting of sea and store it in a bottle from the bottom of the sea as its pure from down side not the upward. I hope it helps bro :)

Reply

Georgianna October 3, 2014 at 5:32 pm

Hello! This post couldn’t be written any better!
Reading this post reminds me of my good old room mate! He always kept chatting
about this. I will forward this article to him.
Pretty sure he willl have a good read. Many thanks
for sharing!

Reply

Pweety One October 8, 2014 at 11:54 pm

Thanks so much! This helped with the exam I am taking. Nice article by the way.

Kay kay!

~Bye!~

Reply

Ninja Queen October 9, 2014 at 12:02 am

itz sorta hard trying to figure this out but now i kinda get it. Thanks

Reply

that guy November 12, 2014 at 5:55 pm

thanks this site helped!

Reply

Alvaro Cerezo February 9, 2015 at 4:51 pm

Thanks :)

Reply

King Louis January 4, 2015 at 6:33 am

The color of the ocean is not due to reflecting the color of the sky, and the greenish color of shallower water is not due to algae or phytoplankton! Since the color of the ocean is not due to reflection, then why is the color of deep water blue and shallow water green? Research it!

Reply

Alvaro Cerezo January 8, 2015 at 4:32 pm

Thanks for the tip. We will! ;)

Reply

mike April 20, 2015 at 8:45 am

Really don’t know y ur saying shit if u dont even know why it happens. How do u know that’s not y its blue. And Wtf does it matter that’s not what the article was about just reminding u it about staying alive while stranded in the ocean which probably could have saved quite a few people if they would have know this information. Which apparently everyone knew according to the dick that left another stupid comment Sry Alvaro Cerezo can’t handle rude And ignorant people and there is an abundance of them on the internet. It was a very good article and u might have saved someone’s life by posting it.

Reply

Alvaro Cerezo April 20, 2015 at 4:57 pm

Thanks so much for your compliments Mike.

King Louis wanted to correct me because I actually made a mistake by saying that the colour of the sea is blue because of the reflecting of the sky. Actually is not exactly true so I removed it from the post :)

Reply

meme February 5, 2015 at 5:19 pm

Meme.

Reply

Alvaro Cerezo April 19, 2015 at 1:11 pm
ryan abubakar February 6, 2015 at 12:59 am

Great article… Very interesting and well written…cheers

Reply

Alvaro Cerezo February 9, 2015 at 4:52 pm

Thanks :)

Reply

Tp March 30, 2015 at 11:00 pm

This helped for an osmosis assignment I had. Thank you so much.

Reply

Alvaro Cerezo April 5, 2015 at 8:35 am

I’m glad to hear that ;)

Reply

RMF April 4, 2015 at 7:20 pm

You say “This is due to the osmosis process where the kidneys can only generate urine which is less salty than the water we drink.”

I would have thought that urine is MORE salty that the water we drink…

Reply

Alvaro Cerezo April 5, 2015 at 8:35 am

Yes you are right.

Reply

Megan McClure April 18, 2015 at 7:51 pm

Actually, the Black Sea water is Brackish, not saline. You could drink a lot more of this water, in fact it is on the borderline of thirst-quenching. 1.7% salt is close to the salt content of urine. It would be a roll of the dice to drink this water, but much less chance of dehydration than seawater.

Reply

Megan McClure April 18, 2015 at 7:51 pm

Glad someone caught those errors!

Reply

King Louis April 19, 2015 at 2:12 am

Megan McClure I forgot to ask him why the sky is blue! Maybe it's because it's reflecting the color of the ocean! Haha!

Reply

imran April 19, 2015 at 12:09 pm

Your this article is very informative. I was just wondering can anyone tell me if there is any part of the world where the salt in the ocean is considerably low.

Reply

Alvaro Cerezo April 19, 2015 at 1:08 pm

Thanks Imran

High concentrations are usually in the center of the ocean away from the mouths of rivers, which brings fresh water. At high latitudes, salinity is low. This can be attributed to lower evaporation rates (because is less shot and the water evaporated is normally from surface) and the melting of ice that dilutes seawater. To sum up, salinity is low where precipitation is greater than evaporation, mainly in coastal or equatorial regions.

On this map you will understand it better
http://bit.ly/1Egclak

Reply

Alvaro Docastaway April 19, 2015 at 12:36 pm

Megan McClure Yes. You are right. In theory. in the Black Sea you will probably have little more chances to survive if you drink its water, but maybe it would be useless as the water you drink will be just to clean the salt. However, as you can see on the map below, if you are in the Romanian – Odessa part of the Black Sea, not far from mouths of rivers, you would probably be able to drink as much as you wanted, but with the risk of getting a very high blood pressure and of course a possible diarrhea :) http://people.iarc.uaf.edu/~gleb/crdf_black_sea/s_04_0.png

Reply

Mike Wolfinbarger April 20, 2015 at 7:24 am

Thanks man if u didn't say it I would have haha ignorance

Reply

Alvaro Cerezo April 20, 2015 at 4:57 pm
Samson John April 26, 2015 at 2:14 pm

Megan McClure Who would get trapped for days in the black sea anyways?

Reply

Leave a Comment

{ 1 trackback }

Previous post:

Next post:

Docastaway