Drinking ocean water is not safe for human consumption. Their water is unsuitable for drinking, making fresh water an incredibly valuable resource, particularly in survival situations.
What Makes Ocean Water Salty?
Ocean water is characterized by its high salt content, primarily sodium chloride. On average, it contains about 3.5% dissolved salts, roughly 35 grams per liter. Sodium and chloride ions make up about 85% of these dissolved salts, with magnesium, sulfate, calcium, and potassium also present.
These salts accumulate from various sources. A major contributor is runoff from land, where rainwater erodes rocks and carries dissolved ions into rivers that flow into the ocean. Hydrothermal vents on the seafloor also release minerals as ocean water seeps into cracks, gets heated, and dissolves elements before being discharged back.
How Your Body Reacts to Saltwater
The human body’s cells require water in a pure form to function properly, and our blood maintains a specific salt concentration, around 9 grams per liter. Ocean water, with its much higher salt concentration, creates an imbalance when ingested. When saltwater enters the bloodstream, the body attempts to dilute the excess salt. This triggers osmosis, drawing water out of the body’s cells and into the bloodstream.
This cellular dehydration places a strain on the kidneys, which filter impurities and excess salt from the blood. Kidneys can excrete some salt, but they produce urine less salty than seawater. To eliminate the high salt load from ocean water, kidneys must use more water than consumed, leading to a net loss of water. Drinking ocean water intensifies thirst and accelerates dehydration, causing symptoms like dry mouth, fatigue, and increased heart rate; as dehydration worsens, serious effects like muscle spasms, seizures, brain damage, or coma can occur, ultimately leading to death.
Other Dangers in Ocean Water
Beyond high salinity, ocean water can harbor other contaminants. Bacteria, such as Vibrio species, live in coastal waters and can cause infections if ingested or entering open wounds. Viruses are also abundant, with billions of viral particles found in a single liter.
Pollutants from human activities also contaminate ocean water. These include plastics (breaking down into microplastics) and chemical runoff from agriculture and industry, containing pesticides, heavy metals like mercury, and pharmaceuticals. Harmful algal blooms, often called “red tides,” are another concern; these excessive growths of algae produce toxins dangerous if contaminated seafood is consumed or airborne toxins are inhaled. Even after desalination, ocean water often requires further purification to remove these biological and chemical threats.