This week’s question comes from my nephew. I pondered the answer for quite awhile, looking at it from many different angles. Because the fact is, there are lots of different things that could make water painful. So without further ado:

1. How long can you survive in COLD water?

This is actually pretty well known based on science that is understood about the human body and what it can endure. It all depends on how cold the water is, your body size and cold tolerance, body fat, and of course whether you are wearing a wet suit or other protective gear.

🥶  In water that is close to the freezing point, around 32.5 degrees Fahrenheit (F), a swimmer would exhaust himself or pass out in fewer than 15 minutes, and would probably only live about 45 minutes.

💧In water that is a little bit warmer but still much cooler than a person’s usual body temperature, say 40-50 degrees Fahrenheit (F), you would last 2-3 times as long. It would take 30-60 minutes before a swimmer was exhausted enough to lose consciousness, and he could survive 1-3 hours waiting for rescue.

💦 In water above 80 degrees Fahrenheit (F), a swimmer could survive for as long as they needed to, without losing consciousness or succumbing to the cold. (1)

2. How long can you survive in WARM water?

So a swimmer can survive in warm water as long as he has floaties or a life vest, without having to worry about hypothermia. Good news for people who enjoy a hot bath! Besides just getting clean a bath can help reduce inflammation, relax and de-stress, and can be almost as good for you as light exercise. (2)

 

But does that mean you can stay in the bath forever?

🛁 Sadly, although I would love to live in the tub, and especially to find a way to write in the tub, humans are not fish and cannot remain in the bath indefinitely. It turns out, you couldn’t last more than 2 or 3 days in warm water. Even water provides pressure against your skin. Think of how it slows you down when you try to walk through water—it’s kind of like extra gravity, right? Well that pressure, over an extended period of time, can reduce your body’s ability to circulate blood, especially to your arms and legs, fingers and toes. They would start to get numb and tingly after enough time, even in warm water, and eventually you would have trouble breathing.

Now just to warn you, this part gets a little gross: Think about when you wear a Band-Aid somewhere that gets wet easily, like your finger—especially nowadays when you have to wash your hands even more than usual. With the Band-Aid on, the skin stays kind of wet, right? And after awhile, if you take that Band-Aid off, the skin that hasn’t been able to dry is a lighter color and very soft. That’s because after a couple of days of constant exposure to moisture, your skin begins to break down. Now imagine that all over your body. After a couple of days in the water, your skin would break down and just fall off. (3)

3. Just how hot is too hot?

🥵 Water boils at 212 degrees Fahrenheit (F), but you can get burned at temperatures much lower than that! Humans can suffer very serious third-degree burns after just 2 seconds in water that is 150 degrees Fahrenheit (F), and in only 5 minutes at 120 degrees Fahrenheit (F). (5)

4. Okay, so somewhere in between 1 and 72 hours is safe, as long as the water isn’t too hot. But how long can you stay in the pool?

🏊🏼‍♂️ The answer to that really depends on the chemicals in your pool. If you have a salt-water pool and so don’t use chlorine or other chemicals, it would be the same as staying in the bath. But most pools contain chemicals that need to be strategically balanced for health. If it’s not balanced properly, then pretty quickly your skin and eyes might burn or feel itchy. You might start to peel, as though you had a sunburn. Even when well balanced, chlorine can irritate your skin, so you probably don’t want to stay in the pool for two days straight! (4)

5. Are there any other exceptions to consider?

☢️ As a matter of fact, there are several bodies of water that could be very painful for humans to survive in. Some, are dangerous because of pollution. The Rio Tinto River in Spain would burn a swimmer because it is so acidic from pollution related to mining for valuable ores like copper, silver, and gold, and that pollution has made it a breeding ground for dangerous bacteria. But don’t worry, this river runs red, as a strikingly visual warning not to enter.

♨️ In Dominica there is a lake called Boiling Lake. Along the edges it is already hotter than 150 degrees Fahrenheit (F), meaning if you dipped your toe in for less than 2 seconds you would have a third-degree burn! The lake gets hotter and begins to boil closer to its center, but its temperature is so high that no one has ever been able to safely measure it. Now that's hot! (6)

🐍 And don’t forget, the abundant sea life. There is a snake that lives in the Great Barrier Reef and other parts of the Pacific Ocean called an Olive Sea Snake. Super venomous, a swimmer could not last long in the water after a bite from this snake. And while most jellyfish won’t kill anyone, the Box Jellyfish off the coast of Australia actually hunts and has very strong venom. Just remember that the ocean is a vast place and generally safe, but it’s always a good idea to keep your eyes open when swimming. (7)
 

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★ Want to learn more? Check out these awesome resources that helped me write this little #Science article:

1. http://www.seagrant.umn.edu/coastal_communities/hypothermia#time

2. https://www.healthline.com/health-news/cant-work-out-try-a-hot-bath

3. https://www.sciencefocus.com/the-human-body/how-long-could-you-live-submerged-up-to-your-chin-in-water/ Parental advisory

4. http://upstatesplash.org/how-long-is-it-safe-for-kids-to-stay-in-the-pool/

5.  http://www.accuratebuilding.com/services/legal/charts/hot_water_burn_scalding_graph.html

6. https://whenonearth.net/8-bodies-of-water-that-will-kill-you/

7. https://www.liveabout.com/ocean-predators-that-can-kill-3023207

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Jean M. Malone - September 2020