6 Surprising Ways to Find Fresh Water in the Ocean

From the olden days to modern times, being lost at sea has been one of the most common nightmares. While humans can go for about three weeks without food in such a desperate situation, we can only survive without water for three days. That’s why one of the first dilemmas you face with surviving being lost at sea is getting fresh water for drinking.

Here are a few ways to get fresh water when lost at sea:

  1. Use the plastic sail in your vessel to collect rain.
  2. Use a clean plastic container to store rainwater.
  3. Distill the seawater with a solar still.
  4. Collect dew for drinking water.
  5. Explore ice as a hydration option.
  6. Try fish fluids to replace water.

If worst-case scenarios keep you up at night, you should be glad to know that there are ways to access fresh water if you are lost at sea. This article will explain how to access freshwater when lost at sea and why freshwater is so vital for survival. Keep reading to find out how to make the most of the limited water resources.

How To Get Fresh Water at Sea

When lost at sea, your two primary water sources are rainwater and seawater, which is undrinkable in its raw, salty state. Rain is preferable because you can easily collect relatively clean, fresh water from it.

However, it doesn’t rain all year round, so rainwater might not be available when you’re at sea. You’ll have to get the salt out of the available seawater in the absence of rain by desalinating it and making the most of the freshwater you get.

1. Use the Plastic Sail in Your Vessel To Collect Rain

At first sight of rain, you must prepare to collect as much water as possible. Most waterborne vessels have sails made of tarpaulin sheets or other waterproof material, which can come in handy for collecting rainwater.

As ocean water splashes on the sail and dries on it, the salt residue often remains stuck to the plastic. You should start by taking down the sheets from the sails and checking for dry salt. If you don’t have plastic sheets available, you could improvise with fabric. As a very last resort, you could even use your clothes.

If there’s salt on the fabric or plastic sheets, wash them in seawater. It won’t take all the salt off since you’re essentially dunking the sheets in salt again. However, the water will help wash off some of the dried stuff so that the salt from the seawater left on the sheets will be less than before.

Use any fasteners you have – nails, ropes, screws – to attach the edges of the sheet to the open parts of your vessel. The sheet shouldn’t be flat; you should make a slight depression in it, so it forms a receptacle for the rainwater. Remember to fasten it firmly to sustain the weight of the rainwater falling into it.

Because of the leftover seawater on the sheet, the first part of the rainwater that falls on the sheet will have more salt than usual. You could collect that into a separate container from the rest of the water. You may use this water to rinse food and clean wounds, while cleaner, less-salty rainwater from subsequent batches can work for drinking.

2. Use a Clean Plastic Container To Store Rainwater

You can’t leave the rainwater in the sheet because it’ll have a much wider surface area if left open. This open area means that the water can easily get contaminated by salty seawater that blows in. Also, when the weather heats up, it will evaporate pretty fast. The storage process is where containers come in.

Plastic containers may not always be available, and you need to store all the rainwater you can get to make the most of it. Cans, plastic bags, or even the inflatable bladder of a life jacket are substitutes for storing fresh water.

3. Distill the Seawater With a Solar Still

You can desalinate seawater using a primitive setup called a solar still. When heated seawater evaporates, the water becomes vapor, leaving the salt behind. The solar still aims to heat seawater using the sun, trap the salt-free condensed water, and collect it into a container. To construct a still, you’ll need the following:

  • A large bowl or the inverted top of a plastic bottle.
  • A smaller bowl, cup, or the bottom half of a can.
  • A waterproof sheet.
  • A small rock.

How To Use a Solar Still

  1. Collect seawater in the larger container and put the smaller bowl inside it.
  2. Firmly cover the larger container with a plastic sheet, and place a rock on the sheet right on top of the smaller container.
  3. As the sun heats the seawater, the vapor will condense on the plastic sheet and fall into the smaller container, leaving the salt residue behind.
  4. Consume the water collected in the container.

4. Collect Dew for Drinking water

In the absence of rain or sun, dew could also be a source of fresh water. Dew gathers much slower than rainfalls, so you’ll need to use every available material to collect the dew.

To collect the condensing dew, you can set the following:

  • Foil
  • Foam
  • Sponges
  • Cotton Fabric
  • Tarp
  • Sailing Sheets
  • Any Clean Surface

In most areas, especially dry ones, dew condenses best at night. You should spread the surfaces in the early evening to cover the broadest possible area and leave them out overnight. To get as much water as possible from it, collect the dew before the sun rises, so it doesn’t evaporate.

5. Explore ice as a Hydration Option

You can augment the fresh water from rain, dew, or distillation with ice in cold regions. More salt is removed when the salty seawater freezes, thaws, and refreezes over a long period.

The blue-gray ice at the tip of icebergs on the salty sea has been frozen and refrozen for over a year, so they have minimal salt. You can suck the ice or melt it to get drinkable water.

When breaking the ice, be careful only to take the tip. The salt that washed out of it will have concentrated in the middle and bottom of the iceberg, so you should avoid those parts. If there are no icebergs you can easily reach, collect some seawater in a container and leave it in the cold to freeze.

6. Try Fish Fluids To Replace Water

Most fish have fluids in them that you can use to get small amounts of drinkable water. Many fish fluids have high amounts of protein that your body will need a lot of water to digest, so you have to be careful about what you drink.

When you catch the raw fish, drink the fluid in its eyes first, as unpleasant as it sounds. The fish eyeball contains vitreous humor, a jelly-like substance made mainly of water. Then, you can cut the fish in half and suck the low-protein liquid inside the spine.

how to get fresh water when lost at sea

Why Do You Need Fresh Water at Sea?

You need fresh water at sea because seawater has an extremely high salt concentration, making it unsuitable for drinking. The human body operates on a very crucial salt-water balance.

Most of our organs continuously work to maintain this delicate balance by keeping the fluid concentration in our bodies reasonably constant through a process of homeostasis.

One of the essential organs in maintaining our internal fluid concentration is the kidney which produces urine to “chuck out” the excess salt in the body system.

You need fresh water at sea because the high salt levels in seawater will affect your body’s internal balance. Your body uses more water in excreting the salt than you initially consumed. So If you drink enough seawater, dehydration could sicken or kill you.

The salt concentration of seawater is about 35,000 parts per million, while drinkable freshwater should have less than 1,000 ppm. When you drink seawater, you’re taking in more than 35 times the usual amount of salt, so homeostasis kicks in to restore balance.

Many organs, including your skin and kidney, will try to eliminate all that salt through urine and sweat. However, urine and sweat also contain water, so the human body can’t excrete dry salt.

The maximum concentration of urine that the kidney can produce is about 20,000 ppm, as opposed to the 35,000 ppm concentration of seawater. This concentration means that the urine your body will begin to produce after drinking seawater will have less salt and more water than the seawater itself.

Scientists from the US Oceanic and Atmospheric Administration (NOAA) estimate that your body will need 1.75 liters (59.2 ounces) to get rid of the salt from drinking 1 liter (33.8 ounces) of seawater. As you urinate 0.75 liters (25.4 ounces)of your body water for every liter of seawater you drink, you get thirstier and, eventually, dehydrated.

Dehydration becomes devastating for the body when it reaches a level where the kidneys can no longer excrete the excess salt. When the salt-water imbalance can’t be corrected, the internal systems that depend on that balance will start to fail.

The nervous system is one of the first to get affected, leading to delirium, coma, and death.

How To Maximize the Freshwater You Get at Sea

Don’t Eat if There’s No Water

Your body will use up a lot of water to digest food. If you don’t have water or your fresh water supply is running low, it would be best to avoid eating. It’s not easy, but your body can go for about seven times longer on low food than on low water. That’s why conserving water is much more critical than eating.

Gradually Reduce Your Water Intake

In an ideal situation, you should drink at least 2.7 to 3.7 liters (91.3 to 125 ounces) of water per day. However, in a tight spot like being lost at sea, your body can survive off a minimum of 1 liter (33.8 ounces) per day without getting dehydrated. Even 55 to 220cl can be sufficient in extreme cases, especially in a cold climate.

Switching to drinking so little water can be a sharp change, so it’s best to ease into it gradually. You can start with a little over 1 liter – about 1.2 liters for the first day before progressively decreasing your ration to 1 liter, 800cl, etc.

When you need to ration freshwater, a drop in water intake can cause symptoms like headaches, dizziness, and constipation.

With prolonged severe dehydration, the symptoms can lead to:

  • Low blood pressure
  • Low blood volume
  • Seizures
  • Kidney failure
  • Coma

When you’re left with minimal water, decreasing your water intake gradually rather than sharply can help to reduce the effects of these symptoms until you can get enough water to revert to drinking a healthy volume.

Eat the Right Type of Food

Even if you have enough drinkable water to eat, you should maximize it by eating food that won’t need a lot of water. Your body needs more water to digest proteins, so you should eat sugary and starchy carbohydrates.

If you can’t eat carbohydrates alone, make them a significant part of your diet. Proteins and dried food need more water to digest, so avoid them. You could eat this food while it’s raining and there’s a lot of drinking water available, but they’re not the best choice when rationing resources.

Drink Water Slowly

Drinking water too fast after dehydration can make you vomit and lose precious freshwater. If it’s your first drink of water in a while, don’t guzzle it all at once. Instead, you should sip the water slowly. No matter how thirsty you are, allow yourself to settle after each sip before taking progressively larger gulps.

Keep Your Body Cool

Sweat takes a lot of water from your body, so you should avoid heat to minimize sweating. Stay under a shade as often as possible, and in hot weather, bathe in the seawater to cool your body.

Seawater can cause boils and rashes on sensitive skin, so you should only use it when necessary. An alternative to bathing in seawater is washing your clothes and putting them on while wet. If rain falls, don’t forget to shower and wash your clothes.


Being lost at sea can be terrifying and desperate, but it is possible to survive and access fresh water if necessary. The methods for getting fresh water at sea include using the plastic sail in your vessel to collect rainwater, storing rainwater in a clean plastic container, distilling seawater with a solar still, collecting dew, exploring ice as a hydration option, and trying fish fluids as a replacement for water.

It is crucial to prioritize obtaining fresh water as a survival tactic, as humans can only survive without water for three days. Being prepared and knowing how to access freshwater can increase your chances of survival if you are ever lost at sea.

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