Drinking ocean water is not safe for human consumption. Directly ingesting seawater can lead to severe health consequences, primarily due to its high salt content. The human body is not equipped to process the significant concentration of minerals found in the ocean, and attempting to do so can worsen dehydration.
Why Ocean Water Isn’t Drinkable
Ocean water contains a high concentration of dissolved salts, primarily sodium chloride, which is common table salt. On average, seawater has a salinity of about 3.5%, meaning every liter contains approximately 35 grams of dissolved salts. This salt content is significantly higher than what the human body can safely process. While our bodies require some salt for proper function, the amount in seawater far exceeds this need.
The biological principle of osmosis explains why this high salt content is problematic. Osmosis is the movement of water across a semi-permeable membrane from an area of lower solute concentration to an area of higher solute concentration, aiming to balance the concentrations on both sides. When seawater, with its high salt concentration, enters the human body, it creates a hypertonic environment in the bloodstream. This causes water to be drawn out of the body’s cells to dilute the excess salt in the blood, leading to cellular dehydration.
What Happens When You Drink Seawater
When a person drinks seawater, the body absorbs the salt into the bloodstream. This influx of salt raises the blood’s sodium concentration to unhealthy levels, creating an imbalance that the body tries to correct. The kidneys, which are responsible for filtering waste and excess substances from the blood, must work overtime to remove this excess salt.
To excrete salt, the kidneys require water. However, the concentration of salt in seawater is higher than the maximum concentration of salt the human kidneys can produce in urine. As a result, the body uses more water to excrete the salt consumed from seawater than the water it gained from drinking it. Drinking seawater causes increased dehydration. Symptoms can quickly escalate from intense thirst, nausea, and vomiting to more severe conditions such as delirium, hallucinations, kidney failure, organ damage, and ultimately, death.
Making Ocean Water Drinkable
Ocean water can be made potable through processes known as desalination. Two primary methods are distillation and reverse osmosis. These technologies remove the dissolved salts and impurities, transforming saltwater into freshwater.
Distillation involves heating seawater until it evaporates, leaving the salts behind. The resulting water vapor is collected and condensed, producing pure water. Reverse osmosis, on the other hand, uses high pressure to force seawater through a semi-permeable membrane. This membrane filters water molecules while blocking salt ions and other contaminants. Both methods are energy-intensive and typically require specialized, large-scale industrial facilities to be efficient. They are not practical solutions for individuals in survival situations due to the complex equipment and significant energy demands involved.