Drinking ocean water is generally not recommended. While oceans contain vast amounts of water, the salt content is far too high for most organisms to safely consume. Additionally, other pollutants and microorganisms in ocean water can cause illness if ingested by humans.
Is ocean water drinkable?
Ocean water is not safe for drinking. The average ocean has a salinity of around 3.5%. This means there are 35 grams of dissolved salts, primarily sodium and chloride, in 1 liter of ocean water. The high salt content makes most ocean water undrinkable for humans.
Drinking high salinity water leads to dehydration as the kidneys expel more water than is taken in while attempting to get rid of excess salt. The recommended maximum sodium intake for adults is around 2,300 mg per day. Drinking 1 liter of ocean water would result in the intake of over 10,000 mg of sodium, more than four times the recommended amount.
What happens if you drink ocean water?
Drinking small amounts of ocean water is unlikely to cause immediate harm in healthy individuals. However, drinking significant volumes can lead to potentially serious health effects:
- Dehydration – As noted above, the kidneys will attempt to excrete excess salt by passing more water, leading to water loss.
- Hypernatremia – Excessively high sodium levels in the blood.
- Nausea and vomiting
- Diarrhea
- Headaches
- Delirium and confusion
- Seizures
- Kidney failure
- Unconsciousness and coma
These effects can occur quite rapidly after drinking significant amounts of ocean water. Even small amounts may worsen thirst and cause diarrhea in sensitive individuals.
Ocean Pollution
In addition to high salinity, ocean water is contaminated with various forms of pollution and microorganisms that can cause illness if ingested:
- Chemical pollution – Toxic chemicals including pesticides, industrial compounds, and oil can be found in areas of ocean water.
- Plastic pollution – Trillions of pieces of plastic litter oceans and can release chemicals.
- Sewage – Pathogens from human and animal waste runoff into oceans.
- Algal blooms – Toxin-releasing algae may proliferate in polluted waters.
- Bacteria – Cholera, E. coli, Salmonella, Vibrio vulnificus and others.
- Viruses – Hepatitis A, Norovirus, and enteroviruses.
- Parasites – Giardia, Cryptosporidium, Toxoplasma gondii.
Consuming ocean water contaminated with these pathogens can cause gastrointestinal illness, respiratory illness, neurological symptoms, liver damage, and other serious health outcomes. The effects can be worse in vulnerable populations like children and elderly individuals.
Can ocean water be made drinkable?
While simply drinking untreated ocean water is not advisable, the water can be made potable using desalination techniques. Desalination refers to processes that remove salts and other substances from saltwater to yield freshwater clean enough for consumption and other purposes.
There are two main types of desalination:
- Thermal distillation – Heating saltwater and collecting pure condensation.
- Reverse osmosis – Forcing water through membranes that filter out salt and impurities.
Desalination requires substantial amounts of energy, specialized equipment, and infrastructure. While costly, desalination is increasingly used to provide freshwater in areas lacking natural supplies, and desalination plants around the world currently produce millions of cubic meters of water per day.
Desalination removes harmful salt content, but additional steps are still needed to remove pathogens and pollution and make ocean water safe to drink. These can include filtering, disinfection, and testing of the finished product before distribution.
When is it safe to drink ocean water?
There are very few instances where ocean water can be safely consumed without desalination or disinfection. These include:
- A sudden, life-threatening shortage of potable water with no other options available.
- Drinking small amounts for temporary hydration, when facing imminent danger from lack of fluids.
- Accidental swallowing of small volumes of well-diluted seawater.
However, these cases carry significant risk and are recommended only as a last resort. Otherwise drinking ocean water should be avoided whenever possible.
Can you drink ocean water to survive?
It is a myth that drinking seawater will help prolong survival in emergency situations. Drinking any substantial amount will likely worsen dehydration and hasten death rather than prevent it in most cases.
Some exceptions where tiny sips may temporarily alleviate extreme thirst include:
- Life raft and similar rescued-at-sea scenarios.
- Short-term survival situations when all freshwater is depleted.
Even then, intake should be minimized and discontinued if nausea, vomiting, or other signs of excess salt intake occur. The body’s thirst mechanism is not adapted to handle the salinity of the modern ocean.
Alternatives like solar stills, rainwater catchment, and moisture condensation should be used to augment freshwater supplies when possible, rather than relying on direct ocean water consumption.
Can you boil ocean water to make it drinkable?
No, boiling ocean water does not make it suitable for drinking. Boiling removes pathogens, but does not remove salts or pollution. The boiled water will retain the same hazardous hypertonicity and salt levels as the original seawater.
In fact, boiling will concentrate salts and compounds as water evaporates, making the salinity even higher and potentially more toxic. Boiling also requires substantial amounts of additional freshwater and fuel, which are unlikely to be in ready supply in survival situations.
Boiling may have limited use in temporary emergencies to remove pathogens from small amounts of seawater that would be potentially lethal if consumed raw. But this carries the same cautions as direct consumption and is not a sustainable solution.
Can dehydration make ocean water drinkable?
No, dehydration does not make ocean water any safer to drink. The human body cannot adapt to handle the salt content of ocean water, no matter how dehydrated a person becomes.
In severe dehydration, the kidneys and thirst mechanisms may be impaired. This decreases the body’s ability to excrete excess salt. Drinking ocean water could hasten death from hypernatremia and its effects, rather than prolong survival.
Dehydration also reduces the volume of water in the body available to dilute ingested salts. So paradoxically, the effects of hypertonic seawater may potentially become worse as dehydration progresses.
Does rainwater make ocean water drinkable?
Rainwater does dilute ocean water slightly. However, it takes high volumes of freshwater mixing to substantially reduce ocean salinity. Rainfall alone does not make ocean water potable.
For example, if 10% of ocean water volume consisted of fresh rainwater, the salinity would decrease just 10-15%. Dangers from hypernatremia and pollution would remain.
In rare cases like concentrated heavy rainfall onto stranded life rafts, salinity could potentially decrease enough to allow temporary survival sips. But rain alone cannot make ocean water a viable potable source without desalination.
Can you safely drink small amounts of ocean water?
Drinking small, occasional mouthfuls of ocean water is unlikely to cause significant harm in otherwise healthy adults. However, it provides no real hydration benefit and may still cause adverse effects.
Nausea, vomiting, and diarrhea can result from even small volumes. With repeated exposure, hypernatremia, kidney problems, and gastrointestinal issues could potentially develop.
Those with underlying medical conditions like kidney disease, hypertension, or cardiac issues may experience severe reactions from even tiny amounts. Individual sensitivity varies, so adverse effects can still occur in anyone.
Infants, small children, elderly individuals, pregnant women, and those with chronic illnesses are at greatest risk from the effects of ingesting saltwater. There is no established “safe” volume, so any intentional consumption is not advised.
Does diluted ocean water become drinkable?
Diluting ocean water can make it safer to drink by lowering salinity and pollution levels. However, significant dilution is needed before it may be considered potable.
As a rough guide, ocean water salinity would need to be reduced to less than 2% to be considered safe for human consumption in an emergency. This equates to diluting 1 part ocean water with at least 15-20 parts freshwater.
Even water diluted to this level may still cause adverse effects in some individuals. Desalination and disinfection provide safer drinking water from ocean water, compared to simple dilution alone.
Can you drink ocean water through dialysis?
Those undergoing dialysis could theoretically tap into the ocean as a water source, using the dialysis machine to filter out salt and waste. However this is not recommended medically.
Reasons include:
- Risk of frequent hypotension and fluid imbalances.
- Difficulty regulating electrolyte levels.
- Machine corrosion and maintenance issues.
- Infection risks from contaminants.
Patients undergoing dialysis have very specialized fluid needs. Tap water or sterile dialysate formulations are used to achieve precise control of solute levels. Ocean water is not a viable option for hemodialysis users.
Conclusion
Drinking ocean water is unsafe in all but the most dire emergencies without desalination or disinfection. While the oceans contain vast quantities of water, the hypertonic salt content makes direct consumption hazardous for humans and most terrestrial animals.
In rare cases tiny sips may temporarily alleviate extreme thirst if facing imminent death from dehydration and no other water source is available. Otherwise, avoidance of direct ocean water ingestion is strongly advised. For prolonged survival, techniques like solar stills, rainwater catchment, or storage of emergency water are recommended over drinking seawater.