You would think there would be little difference when drowning. After all, water is water and getting enough of it into your lungs can be fatal. As morbid as it is to think about, there is a noticeable difference. Drowning in salt water is completely different than drowning in fresh water.
Which Is More Dangerous, Salt Water or Fresh Water?
Fresh water appears to be the more deadly variety since more people drown in fresh water every year than in salt water. But is there a reason for this, or is it just a statistical correlation due to fresh water simply being more common in our everyday lives?
Aside from the fact that fresh water filled swimming pools are incredibly common throughout the United States, our bodies actually have a completely different physiological reaction depending on which type of liquid filling our lungs. There is also a discrepancy between the time it takes to drown in the different liquids as well. The time it takes to drown in saltwater is between 5-30 minutes, while with fresh water, it only takes between 5-20 minutes.
Why The Difference?
In cases of fresh water drowning, the water filling someone’s lungs is considered ‘hypotonic‘ to the blood. The fresh water seeps its way into the blood stream where it dilutes your plasma/electrolytes. This causes the red blood cells to swell up and eventually burst.
Also, and more obviously, the fluid filling a person’s lungs will prevent the body from taking in enough air. Not being able to take in air means your body can’t get the much needed oxygen it needs to function. This will lead to eventual cardiac arrest. An individual who is drowning will likely be unconscious before the heart stops, however.
Drowning in saltwater is an entirely different beast. When the lungs fill with saltwater, it has the opposite effect and becomes ‘hypertonic‘ to the blood passing nearby. The plasma in our blood gets sucked into the lungs and fills it, preventing gas/air exchange. No air exchange, no oxygen entering the bloodstream. Without oxygen, our hearts give up and we go unconscious and eventually die.
In other words, you drown in your own fluids.
Bonus Fact: Children are more likely to drown in fresh water, adults in saltwater.
Lunetta, P. & Modell, J.H. (2005): Macropathological and Laboratory Findings in Drowning Victims.
J.C. van Dorp, J.J.L.M. Bierens, Final Recommendations of the World Congress on Drowning 26—28
“Children Drowning, Drowning Children“. The Alliance for Safe Children.
DiMaio, M.D. Vincent J.M. (June 28th, 2001). Forensic Pathology, Second Edition. Taylor & Francis. pp. 405
Gorman, Mark (2008). Interface of Neurology and Internal Medicine. Lippincott Williams & Wilkins. pp. 701–708.