How to Remove Salt From Water to Make It Drinkable: A Practical Guide

How to Remove Salt From Water to Make It Drinkable: A Practical Guide

Access to clean, safe drinking water is a fundamental necessity. In situations where your only water source is saltwater – like the ocean, brackish wells, or even some processed foods that leach salt into their liquid – you might find yourself wondering if there's a way to make that salty water safe for consumption. The answer is a resounding yes, but it requires a process known as desalination. Desalination is the removal of salts and other minerals from water. While large-scale desalination plants are a marvel of modern engineering, there are several methods you can employ on a smaller scale, some even suitable for survival situations.

Understanding Why Saltwater Isn't Drinkable

Before diving into the "how," it's crucial to understand the "why." Our bodies need water to function, but they also have a specific balance of electrolytes, including sodium. When you drink saltwater, your body tries to get rid of the excess salt. To do this, your kidneys need more water than you're consuming to excrete the salt. This ultimately leads to dehydration, which can be dangerous and even fatal. Drinking saltwater doesn't quench your thirst; it exacerbates it.

Methods for Removing Salt from Water

There are several effective methods for desalinating water. The most common and practical for individuals are:

1. Solar Still (Evaporation and Condensation)

This is perhaps the most accessible method, especially in sunny climates and survival scenarios. It mimics nature's own water cycle.

How it Works:

You're essentially using the sun's energy to evaporate the water, leaving the salt behind, and then collecting the pure, condensed water vapor.

What You'll Need:

• A large container (e.g., a basin, a large pot, a clean tarp)
• A smaller collection container (e.g., a cup, a smaller bowl)
• Clear plastic sheeting or a clean, transparent tarp
• A small rock or weight
• Saltwater

Steps:

1. Place the smaller collection container in the center of the larger container. Ensure the top of the collection container is lower than the rim of the larger container.
2. Pour the saltwater into the larger container, being careful not to get any into the smaller collection container.
3. Cover the larger container with the clear plastic sheeting or tarp, sealing the edges as best as possible.
4. Place the small rock or weight in the center of the plastic sheeting, directly over the collection container. This creates a downward slope.
5. Place the solar still in direct sunlight.
6. The sun will heat the saltwater, causing it to evaporate. The pure water vapor will rise and condense on the cooler underside of the plastic sheeting.
7. As condensation forms, it will run down the sloped plastic and drip into the collection container.

Pros: Simple, requires no electricity, effective in sunny conditions, can be made with readily available materials.
Cons: Slow process, produces small quantities of water, dependent on sunlight.

2. Boiling and Condensation (Distillation)

Similar to a solar still, but uses heat from a fire or stove instead of the sun.

How it Works:

Boiling the saltwater turns it into steam (pure water vapor), leaving the salt and impurities behind. This steam is then collected and condensed back into liquid form.

What You'll Need:

• A pot with a lid that fits well
• A smaller heat-resistant container that can fit inside the larger pot
• Saltwater
• A heat source (fire, stove)
• Ice (optional, but speeds up condensation)

Steps:

1. Place the smaller collection container inside the larger pot.
2. Pour the saltwater around the smaller container, ensuring no saltwater gets into it.
3. Invert the lid of the pot. This is crucial because you want the condensed water to drip back into the collection container, not onto the food you might be boiling.
4. Place the pot on your heat source and bring the saltwater to a boil.
5. As the water boils, steam will rise and hit the cooler underside of the inverted lid. It will condense into pure water.
6. If you are using ice, place some on top of the inverted lid to cool it down more rapidly and increase condensation.
7. The condensed water will drip from the lowest point of the inverted lid into your collection container.
8. Continue boiling until you have collected a sufficient amount of water.

Pros: Faster than a solar still, effective even without direct sunlight.
Cons: Requires a heat source and fuel, uses more energy, can be dangerous if not done carefully.

3. Reverse Osmosis (RO) Water Filters

This is the technology used by most large-scale desalination plants and is also available in smaller, portable units.

How it Works:

Reverse osmosis uses a semipermeable membrane to separate water molecules from dissolved salts and other impurities. Pressure is applied to force the saltwater through the membrane, with the pure water passing through and the salt being rejected.

What You'll Need:

• A portable reverse osmosis water filter system (available from camping and survival gear retailers)
• Saltwater

Steps:

1. Follow the manufacturer's instructions for your specific RO system.
2. Typically, you will pump or gravity-feed the saltwater into the system.
3. The system will then push the water through the RO membrane.
4. One outlet will produce purified drinking water, while another outlet will discharge the concentrated brine (wastewater).

Pros: Highly effective, produces pure water quickly, portable options available for camping and emergencies.
Cons: Can be expensive, requires a power source (for some units), produces brine wastewater, membranes can clog.

4. Freezing

This method relies on the fact that pure water freezes at a higher temperature than saltwater.

How it Works:

When saltwater freezes, the ice crystals that form are mostly pure water, with the salt becoming concentrated in the remaining liquid brine.

What You'll Need:

• A container
• Saltwater
• A freezer or very cold environment

Steps:

1. Pour saltwater into a container and place it in a freezer or a very cold environment.
2. Allow the water to freeze until a significant portion has turned into ice, but some liquid brine remains.
3. Carefully pour off the remaining liquid brine, which will be much saltier than the original water.
4. You can then melt the ice to obtain drinkable water.
5. For even purer water, you can repeat the process by refreezing the melted ice and pouring off the brine again.

Pros: Simple, requires no special equipment beyond a freezer or cold environment.
Cons: Inefficient, slow, requires extremely cold temperatures, may not remove all salts.

Important Note: Any method you use to desalinate water, especially in a survival situation, should be followed by purification if there's any doubt about the initial water source's cleanliness from bacteria or viruses. Boiling, chemical purification tablets, or UV purification are all good options.

Which Method is Best for You?

The best method for removing salt from water depends heavily on your circumstances. For casual use in a well-equipped home, a reverse osmosis system might be ideal. For camping or survival, a solar still or boiling method are more practical. Freezing is a last resort due to its inefficiency.

Frequently Asked Questions (FAQ)

How does distillation remove salt from water?

Distillation works by heating saltwater to its boiling point, turning it into steam (pure water vapor). The salt and other impurities are left behind in the original container because they do not evaporate. This steam is then cooled and condensed back into liquid form, resulting in purified, drinkable water.

Why is saltwater bad for you to drink?

Drinking saltwater is bad for you because your body needs to maintain a specific balance of salt and water. When you consume saltwater, your kidneys must work harder to excrete the excess salt. To do this, they require more water than you are taking in, leading to dehydration. This can cause symptoms like nausea, vomiting, and can ultimately be life-threatening.

Can I drink water from a portable reverse osmosis filter if it's saltwater?

Yes, many portable reverse osmosis (RO) water filter systems are designed to desalinate saltwater and brackish water, making it drinkable. However, it's crucial to ensure that the specific RO system you are using is rated for saltwater desalination. Standard portable water filters are typically designed to remove sediment and bacteria from fresh water and will not remove salt.

How long does it take to get drinkable water using a solar still?

The time it takes to produce drinkable water using a solar still varies greatly depending on the size of the still, the intensity of the sunlight, and ambient temperature. On average, a well-constructed solar still in optimal conditions might produce anywhere from 1 to 4 liters (about 1 to 4 quarts) of water per day.

Is boiling saltwater enough to make it drinkable?

No, simply boiling saltwater is not enough to make it drinkable. Boiling kills bacteria and viruses, but it does not remove the salt. The salt will remain in the water after boiling. You must use a method like distillation or reverse osmosis to separate the salt from the water.