Desalination is the process of removing salt from salt water. Human beings cannot drink salt water: if you drink it by mistake, you can have serious damage. All the simple methods for removing salt from water follow a basic principle: evaporation and collection. This article illustrates several techniques that you can use to boil salt water and recover fresh water from steam or condensation, ranging from the simple gas stove method, to an extreme survival method to one that uses the sun.
Steps
Method 1 of 3: Using a Pot and Stove
Step 1. Get a large pot with a lid and an empty glass
The latter must be large enough to contain a fair amount of fresh water.
- Get a glass that is low enough to fit into the pot without hindering the lid from placing.
- A Pyrex or metal mug is safer, as some types of glass will burst if exposed to excessive heat, while the plastic may melt or warp.
- Make sure the pot and lid are suitable for use on the stove.
Step 2. Slowly pour some salted water into the pot
Don't overfill it.
- Stop well before the water level reaches the edge of the glass.
- In this way you are sure that the salty water does not splash inside the glass while it is boiling.
- You must avoid that the one containing salt enters the glass, otherwise it contaminates the one you want to make drinkable.
Step 3. Put the lid upside down on the pot
This allows the condensed water vapor to drip into the glass.
- Place the lid so that the top point or knob is facing down directly over the glass.
- Make sure the lid seals the edges of the pot.
- If there is not a good seal, a lot of steam will come out and reduce the amount of fresh water you can produce.
Step 4. Bring the water to a simmer
You need to bring it to a slow boil on a low heat.
- If the boil is too lively it can contaminate the drinking water in the glass with sprays.
- Too much heat risks breaking the glass if it is made of glass.
- Furthermore, if the water boils rapidly and violently, the glass can move from the center of the pot and the lid knob would no longer allow the steam to flow into it.
Step 5. Check the pot as the water condenses
When the water boils, it becomes pure vapor, losing everything that was dissolved in it.
- When the water becomes steam it condenses in the air and forms water droplets on the surface of the lid.
- The droplets then flow to the lowest point (knob) falling into the glass below.
- This process could take 20 minutes or more.
Step 6. Wait some time before drinking the water
The glass and water will be very hot.
- A small amount of salted water may remain in the pot, so when you remove the glass, be careful that some of this water does not fall into it.
- Probably the glass and drinking water cool faster if you remove them from the pot.
- Be careful not to burn yourself when you remove the container from the pot. Use an oven mitt or pot holder.
Method 2 of 3: Using a Solar Desalinator
Step 1. Collect the salt water in a bowl or container, but don't fill it to the brim
- There must be some space in the upper part of the container, so that the salt water does not splash into the drinking water collector.
- Make sure the bowl or container has an airtight seal. If it leaks, the salt water will risk leaking before turning into steam and condensing into drinking water.
- This method can only be used if there are many hours of sunlight, as it takes a long time.
Step 2. Carefully insert a smaller cup or vase into the center of the container
- If you put the glass hastily you risk splashing a little salt water inside and consequently contaminating the drinking water when you have collected it.
- Make sure the rim of the glass stays above the water level.
- You may need to put a stone as a weight to keep it from moving.
Step 3. Cover the bowl with cling film
Make sure the wrap is not too loose but not too tight either.
- The plastic must have a good seal on the edge of the salt water container.
- If it doesn't close properly, the steam could escape and frustrate your efforts.
- Use good quality plastic wrap so it doesn't tear.
Step 4. Place a rock or weight in the center of the cling film, placing it right over the cup or container in the center of the bowl
- In this way, the plastic casing tilts in the center, allowing the steam that is formed to drip right inside the cup.
- Make sure the rock or weight is not too heavy, otherwise it can tear the plastic.
- Make sure the cup is in the center of the bowl before continuing.
Step 5. Place the salt water bowl in direct sunlight
This heats the water and causes condensation to form under the cling film.
- As condensation forms, a few drops of steam begin to descend from the plastic wrap and fall into the cup.
- This process allows you to slowly collect drinking water.
- As already mentioned, this is a method that takes several hours, so you have to be patient.
- Once you have enough water in the cup, you can drink it. It is safe and completely desalinated.
Method 3 of 3: Desalting the Water to Ensure Survival
Step 1. Retrieve your life raft and any other debris
You can use the same parts of the raft to build a structure to make the sea water drinkable.
- This method is very useful if you find yourself stuck on a beach and don't have drinking water.
- It is a method developed by a pilot who was isolated in the Pacific during World War II.
- It is especially useful if you do not know how long you will have to wait before help arrives.
Step 2. Take a gas cylinder from the material you recovered from the raft
Open it and fill it with sea water.
- Filter the water through a cloth so that too much sand or other debris does not enter.
- Do not overfill the container. You must prevent it from overflowing from the cylinder.
- Bring the water to an area where you can light a fire.
Step 3. Retrieve the life raft inflation hose and valves
Connect the hose to one end of the valve.
- In this way, you allow the condensed water vapor to escape from the container through the tube, once the sea water is heated.
- Make sure the hose is not blocked or kinked in any area.
- Check that the hose has a good seal and that there are no leaks, to avoid spillage of drinking water.
Step 4. Insert the valve into the top of the gas cylinder
Use the opposite end from where you connected the hose.
- In this way you have created a path that the water vapor can travel out of the cylinder as the water heats up and then exits at the other end as fresh water.
- Make sure the valve fits snugly to avoid leaks.
- If you have duct tape or string you can use this to strengthen the closure.
Step 5. Bury the pipe under a mound of sand, so as to keep it stable while the water flows through it
- However, keep the end of the hose exposed, as this is where the drinking water will come out.
- Do not bury the gas cylinder or the cap, they must remain exposed in order to check that there are no leaks.
- Check that the pipe is quite straight and that it has no kinks or kinks when you place it in the sand.
- Place a pot under the exposed end of the hose to catch the drinking water that will come out.
Step 6. Build a fire and place the gas bottle directly over the flame
By doing this, boil the salted water inside.
- When the water boils, the vapor condenses at the top of the cylinder and travels through the tube in the form of drinking water.
- As most of the water boils, the condensed vapor flows through the tube out and into the pot.
- The water you recover in this way will be desalinated and drinkable.
- Make sure it is cold before drinking it.
Advice
- The method of evaporation and condensation of water is called distillation. You can also use it for regular tap water, when you need to distil it.
- It may be useful to be able to cool the lid while the water is boiling, in this way condensation forms more quickly. To cool the lid, you can use cold salted water and change it when it gets too hot.
- The sun method takes a long time and may not be enough to get enough drinking water quickly.
