The process of water softening removes magnesium, calcium, and several other metal cations from hardened water, but it does not necessarily remove all sodium from it.
Sodium is critical for the normal functioning of the human body and is present in all fluids and tissues. Therefore, it is not typically considered harmful if consumed at normal intake levels from drinking water sources.
Although the salt content present in softened water does not necessarily pose a health risk, some people may require low sodium consumption in their diets or simply prefer low sodium content in their drinking water.
The amount of salt in the softened water also depends upon the hardness of the original water. All of these instances make removing salt from water necessary, with the most effective and common way being physical filtration.
When consumed in large quantities, saltwater can prove quite harmful to the body, even resulting in death due to dehydration. Saltwater consumption does not quench thirst: it only increases the quantity of salt in the body, causing dehydration.
However, there are several other desalination methods that you can employ to remove salt from softened water, along with various other contaminants typically found in salt water.
Let’s take a look at them!
Methods for Removing Salt from Water
Reverse Osmosis
Osmosis is a systematic process crucial for normal body functioning and generally happens all around us. This process refers to the movement of a liquid from a medium of low solute concentration moving across a semipermeable membrane to a medium with a high solute concentration.
This movement continues until the liquid on both sides of the semipermeable membrane attains the same solute concentration. A force known as osmotic pressure causes this movement.
As the name entails, reverse osmosis is the exact opposite of the natural osmosis process. Since desalination removes salt from water, reverse osmosis is an effective method for this process.
The process of desalination through reverse osmosis forces salty, soft water at pressure through a semipermeable membrane. This pressure must be higher than the osmotic pressure to overpower the natural osmosis process and push the water to reverse osmosis.
The membranes used for this process have large pores that easily allow water molecules to seep through them, but they are not large enough to allow sodium ions and several other contaminants found in soft water through.
Thus, the reverse osmosis process allows fresh water to accumulate on one side of the membrane, with a vast majority of sodium removed.
Distillation
Distillation is another common desalination method for soft water. Water distillation involves a water distiller, which boils water until it evaporates, leaving an accumulation of minerals and salt behind in the boiling chamber.
The evaporated water then travels through a cooling corridor, resulting in drop-by-drop condensation into a container.
Since most distillers function as countertop units, users do not need to manually transfer the softened water from a faucet to a distiller. Distillation is, however, a lengthy process and removes the minerals from water that give it a nice and fresh taste.
Ion Exchange
Ion exchange is a traditional desalination method for softened water and involves the physical removal of naturally occurring mineral ions from the water. These mineral ions are responsible for the scale and generally include magnesium and calcium carbonate.
The ion exchange process involves a resin bed filled with tiny gelatinous beads wholly covered in sodium ions. Hard water is made to pass through this sodium-coated softener, where the magnesium and calcium ions exchange their places with the sodium ions that cover the resin beads.
Although the ion exchange method removes several hard minerals and salts from the softened water, it also causes an increase in its sodium content.
The softening system continues to regenerate, replenishing the sodium ion amount in the resin bed and removing the accumulated hardness minerals.
Although some quantity of water-softening brine solution may enter your drinking water from the ion exchange system, the quantity is typically too small to cause an abnormal increase in the amount of sodium in your water.
However, this process may not be your first choice if you do not intend to consume sodium quantities, no matter how small it may be.
Deionization
Deionization is one of the most common water filtration methods used to remove all kinds of dissolved salts from softened water. This process prompts salt removal from soft water by forcing water flow through two ion exchange materials.
It is a common industrial concept to use the term deionization and demineralization somewhat interchangeably. Although the term demineralization can also be used for this process, deionization is a more suitable and accurate terminology.
Water passage through the primary ion exchange material removes magnesium and calcium ions from the water, similar to a traditional water softening process. However, this process differs from home equipment in that the deionization units also remove all other positive metallic ions, replacing them with hydrogen ions instead of sodium ions.
Comparison of Desalination Methods
Reverse osmosis is a natural and highly effective desalination method for soft water and is known to dramatically reduce the number of contaminants in the water.
The reverse osmosis system can effectively remove or reduce minerals and metal ions, sodium, nitrates, bacteria (such as salmonella), viruses (including norovirus), protozoa (giardia), perfluoroalkyl substances (PFAS), and concentrations of other contaminants.
Reverse osmosis systems are also equipped with a pre-filter that clears out all sediments and a post-filter made of activated carbon. The activated carbon filters are highly effective at filtering out several substances that give tap water an undesirable smell and taste.
These elements typically include disinfectants such as chloramines, chlorine used in water treatment, and volatile organic chemicals (VOCs). Other desalination processes are similarly effective, but each has pros and cons.
For instance, although distillation is an effective desalination method, it is slow, time-taking, and requires a constant heated energy source. Although attempts to use solar energy as this heat source have been made, this energy form is only used to treat small water quantities and is tricky to maintain at a constant temperature.
The apparent inefficiency of solar power systems calls for a shift to more costly energy forms, increasing the cost of the distillation process.
Additionally, one may need to complete the distillation process several times to ensure significant water purity. So it might take several hours to attain one gallon of purified and cleansed water. One typically needs five gallons of tap water to attain one gallon of purified water.
Both reverse osmosis and distillation strip water of its natural trace elements during the desalination process. Removing such elements increases the relative proportion of hydrogen composition in the water, making it considerably acidic.
Several studies have shown that drinking such distilled water stripped of its natural minerals can prove harmful to the human body, and long-term consumption can cause mineral deficiencies in the body. Thus, the demineralization that comes with desalination through distillation and reverses osmosis is not desirable.
Although removing these trace elements renders the water ideal for use in print or photo shops, it is not very suitable for drinking in terms of taste and health benefits.
This brings our attention to the ion exchange method, widely used as a desalination method for water treatment in both municipal and industrial water treatment systems. This process boasts several advantages over other treatment methods: it is environmentally friendly, has a low maintenance expenditure, and provides a higher flow rate of treated water.
However, there are certain disadvantages associated with the ion exchange method as well. These include bacterial contamination, calcium sulfate fouling, chlorine contamination, iron fouling, absorption of organic matter, and organic contamination from resins.
Similarly, the deionization process can also produce highly purified water, quite similar to distilled water, since most of the non-particulate water impurities are dissolvable in salt. The deionization process is also faster than distillation and does not build up the scale.
However, deionization can not remove uncharged organic particulates and molecules, as well as viruses and bacteria, if you do not use incidental trapping in the resin. Deionized water is also not desirable for drinking and may pose health hazards when consumed for long periods.
DIY Solutions to Remove Salt From Water
Apart from these industrial desalination procedures, there are certainly easy, homemade procedures that you can undertake to remove salt from water. You can easily use household items to make your own water desalination system.
Soda Can and Plastic Bottle
You can easily desalinate water at home, even if you do not have pots and pans and are stuck in a survival situation. All you need is a soda can and a plastic bottle, and you can make salinated water drinkable in a few easy steps!
- Take the largest plastic bottle you can find and cut off its bottom by using either scissors or a sharp knife. If you do not have either, you can use the sharpest object you can get your hands on.
- Find a soda can and use your scissors or knife to cut its top off.
- Make an inner gutter by turning the bottom of the plastic bottle inside. Fill the soda can with salt water and place the bottomless plastic bottle on top of it. Make sure that the inner gutter of your plastic water bottle looks like a dry moat around your soda can.
- Place your desalination plant under direct sunlight. Allow the salt water to evaporate and run down the inner edges of your bottomless plastic bottle.
- Wait for the inner gutter to fill up with fresh water before taking a sip. Continue refilling your soda can with more saltwater until you have your desired freshwater quantity!
Using a plastic bottle and soda can prove quite time-consuming. However, this process can prove life-saving in particular survival situations! As long as your desalination system works effectively, you are good to go.
Solar Sill Desalination
Solar desalination is an effective desalination method that has stuck around for centuries and so is quite reliable. According to the United States Geological Survey (USGS) recommendations, you can quickly build your desalination plant at home by using a solar sill. The solar sill requires only a few materials and can be used as a reliable source of drinking water.
All you need to do is follow the following steps:
- Dig a considerably deep pit in the ground. Make sure it is big enough for a water tank or large bowl. The larger the hole you dig, the larger will be your water container.
- Place a bowl or water tank at the bottom of the pit. This container will be used to catch the condensed water.
- Cover your pit with a plastic sheet or tarp, but do not worry about sealing it shut too tightly, as you do not need to make it air-tight.
- Place a small object or a rock in the middle of your pit’s plastic covering. Make sure that the rock or small object is directly above your water container, and it will ensure that the condensed water flows seamlessly to the middle and only drips into your tank.
- Fill the pit with salt water, and ensure that no water seeps into the container you put at the bottom of the pit. Fill up the hole as high as one to two inches, or 2.54-5.08cm, ensuring that it is below the upper edge of the water container.
- Leave the solar sill for a few days or overnight. The sunlight would bring you clean drinking water in about 12 to 24 hours.
This process is also quite time-consuming but is quite an effective desalination method, provided you are only using the sun. However, you can speed up the process by digging your pit in a place that gets plenty of direct sunlight and removing all debris or foliage that may block any sunlight.
This desalination method, also known as water distillation, has been around for around 2,000 years and is a tried-and-true method of desalination.
Water Evaporation Method
Using evaporation to remove salt from water is one of the most convenient and cleanest ways of getting fresh water, as this process removes all kinds of salts, bacteria, and other harmful chemicals that may be present in the water.
This easy process only requires you to have a glass, a large pot, and a separate pot with a lid. Follow the following steps, and you can set up your own desalination plant with household items!
- Put a large pot on the stove and place a glass bowl or tall glass in its middle. Make sure that the glass is not taller than the pot of water; it is recommended to leave about two or three inches – about 5.08 to 7.62 cm – of space at the top.
- Fill the pot with water until the waterline reaches one to two inches – 2.54 to 5.08 centimeters – below the rim of your glass.
- Place the pot’s lid upside down to ensure the lid’s handle can fit over the glass in the middle. If you do not want to do so, you can cover your pot with plastic wrap and place a small rock or another small object above the glass. Make sure you create a dip above the glass to allow the condensed water droplets to fall inside it.
- Boil the water slowly over low heat, and make sure that the condensation flows to the center portion of the lid or plastic wrap, ensuring that the condensed molecules drip directly into your cup.
- Once your glass is full of fresh water, turn the heat off and take the glass out. The water accumulated inside it is fresh water, desalinated through evaporation.
Safety Precautions
Although the above-mentioned home remedies and industrial desalination procedures may sound convenient and easy to handle, they require the utmost level of precision and care. Since most of the procedures involve heat or chemicals, it is crucial to handle them with care, lest you end up hurting yourself or interfering with the desalination procedures.
It is imperative that you take the necessary precautions before drinking desalinated water and ensure that its salt content is adequately concentrated.
Mishandling of the equipment or failure to set up the desalination system in the prescribed ways can fail to remove salt from your water, and thus it is essential to test the water for salt before consuming or using it.
Conclusion
Removing salt from softened water is possible through various methods, each of which comes with its own list of pros and cons. It is critical to compare each method’s safety precautions, effectiveness, cost, and maintenance before choosing one.
Although you can also remove salt from water using certain DIY solutions, it is essential to note that these processes may not be as safe or effective as the industrial and professional ones.