What Happens if You Drink a Lot of Salt Water?

Max. D Gray
By Max. D Gray. Updated: January 16, 2017
What Happens if You Drink a Lot of Salt Water?

Have you ever daydreamed about being marooned on a desert island? Did you play Robinson Crusoe as a child? Well, when your mind wanders off, ask yourself what would be your source of drinking water, or learn tricks to make salt water drinkable. You'll be prepared... Just in case.

Seventy-one percent of the surface of our planet is covered with water, but most is ocean water that we cannot consume due to its salt. In this OneHowTo article we'll tell you what happens if you drink a lot of salt water.

You may also be interested in: Fruits That Reduce Water Retention


  1. Physical effects of salt and water
  2. Potential effects of drinking salt water
  3. Characteristics of salt water
  4. Consequences of drinking salt water

Physical effects of salt and water

As vital drinking water runs out, it may begin to seem like the sea is mocking you because you cannot drink any of it. Consuming salt water does not sound as deadly as, for example, having pufferfish for dinner, does it? After all, our bodies need both water and salt to function.

Water, being the solvent for proteins and the like, is essential for chemical reactions that help us metabolize food. Water is also used by our muscles, to pump blood, and even to think. Our cells also depend on salt, which exists as sodium and chloride ions in our extracellular body fluids, for the same chemical reactions. Drinking saltwater sounds efficient, and non-fatal. So what is the problem?

What Happens if You Drink a Lot of Salt Water? - Physical effects of salt and water

Potential effects of drinking salt water

Have you ever been in a lift when an overly perfumed person gets in? The scent spreads out everywhere in the elevator, so everyone can smell it. That is the action of diffusion. Materials are constantly transported from regions of high concentration to regions of lower concentration, moving all the time.

When it comes to diffusion and salt water however, the human cells have biological membranes that can prevent salt from flowing freely into cells. Although the body can regulate sodium and chloride concentrations to some extent, a very high concentration of salt in the blood is a challenge. That is because a cell membrane is semipermeable - although sodium, chloride, and other substances may not be able to diffuse easily in and out of the cell, water can.

When the salt concentration is higher outside the cells than inside, water moves from the inside to the outside of cells to correct the imbalance. The attempt to equalize the concentrations of matter on both sides of a semipermeable membrane is called osmosis.

If you are consuming seawater the results of osmosis will be spectacularly disastrous. Remember that the level of salt in seawater is almost four times higher than that of body fluids. If left unchecked, the transfer of water from inside the cells to the outside will cause the cells to contract significantly - and contraction is not good.

What Happens if You Drink a Lot of Salt Water? - Potential effects of drinking salt water

Characteristics of salt water

Although a certain level of salt consumption is essential to our physiological well-being (and makes chips taste better), too little or too much salt wreaks havoc on our body.

For humans, the magic number is 9. That's the ideal level of salinity, that is, the grams of salt dissolved in 1000 grams of water in human blood. This means 1000 grams of fluid containing 9 grams of salt and 991 grams of water. In medicine, fluids that have the same salinity as blood are known as isotonic. When we consume too much salt, the excess is excreted in the urine to maintain isotonic body fluids.

Salt water is a hypertonic liquid - it contains more salt than human blood - and has a salinity of 35. As you're about to see, drinking hypertonic fluids such as seawater creates chaos in the defense mechanisms of the human body.

Consequences of drinking salt water

Unless you drink lots of fresh water, the mechanism for regulating your body is in a life-threatening situation. The change in concentration of sodium outside the cells is the main culprit for that situation. In order to return to an isotonic state, which is necessary for cell survival, the body tries to remove excess sodium from your extracellular fluids through urine. Therefore, in order to eliminate the extreme amount of sodium, you pass more water in your urine that what you actually drink. This leads to internal dehydration.

So if you drink a lot of seawater, you are actually not hydrating your body, you're dehydrating it. This leads to muscle cramps, a dry mouth and even more thirst.

The body tries to compensate for the fluid loss by increasing heart rate and constricting blood vessels, to maintain pressure and blood flow to vital organs. Unlike normal drinking water, these waves breaking on the shore will not lower your blood pressure all that much. You are also more likely to feel nausea, weakness, or even delirious. As you dehydrate, your defense mechanism fails. If you do not drink fresh water to reverse the effects of excess sodium, your brain and other organs will receive less blood, leading to a coma, organ failure and death.

Of course, drinking small amounts of salt water will not kill you. The message however, is clear; salt and water are better consumed separately and any product with salt must be accompanied with fresh water.

This is what happens if you drink a lot of salt water: As you can see, it's simply not a good idea.

If you're looking for more inspiration in case you get stranded, take a look at our article on Alexandre Selkirk, the real-life inspiration behind Robinson Crusoe!

This article is merely informative, oneHOWTO does not have the authority to prescribe any medical treatments or create a diagnosis. We invite you to visit your doctor if you have any type of condition or pain.

If you want to read similar articles to What Happens if You Drink a Lot of Salt Water?, we recommend you visit our Healthy living category.

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What Happens if You Drink a Lot of Salt Water?