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How to make fresh water from salt water?

One of the most important factors affecting the quality of drinking water is its salt content. If the salinity is too high, the water acquires a salty-bitter aftertaste. If the amount of salt exceeds the permissible norms, this can have an extremely negative effect on the health of people who use such water.

Also, water containing a large amount of salt is extremely undesirable to use for domestic purposes. Washing and dishwashers, as well as other household appliances, will quickly fail under the influence of salt deposits. But how to desalinate water and avoid such consequences?

Desalination Methods

Water comes to residential buildings from artesian wells. In all respects, such water is not allowed for consumption, but for lack of other water people still drink it, cook food on it, and use it for household needs. Therefore, the water entering the house must be desalinated. Artesian water can be desalinated in various ways. The only problem is that they are all expensive.

The simplest method is distillation of water, but salts formed during the evaporation of fresh water clog pipes and impair thermal conductivity. The most effective way is thermochemical softening of water. The method is quite effective, but also expensive. It significantly increases the cost of fresh water obtained in the process, and in addition, in the course of work a large number of by-products are formed, which must be disposed of. Everyone knows that the disposal of harmful substances is very expensive, which also does not affect the final price in the best way.

Fill a large container with salt water Put a smaller capacity in a large Cover the large container with plastic Put a small stone in the center of the plastic coating Put the containers in a sunny place for several hours Open the lid and take out a smaller container with fresh water

Solar desalination is a method in which evaporation under the influence of solar radiation occurs in a large container with artesian water. This method is used not only for desalination of fresh water, but also for groundwater. The difficulty lies in too much expensive equipment. This method is used, as a rule, in countries with large solar radiation.

How to desalinate sea water

People themselves began to change the environment, actively intervene in natural processes, and as a result, they received huge problems. One of the pressing problems is that many countries suffer from a shortage of fresh water. Clean drinking water is becoming less and less. And this contributes to the development of the production of specialized equipment, the discovery of new technologies, which allows desalination of sea water. The countries of Africa, Israel, the north of Europe are located near sea water, but it cannot be used as drinking water. We have to desalinate sea water.

In order to purify sea water from salt impurities, it is necessary to use expensive equipment that requires large energy costs. And even so, there are a large number of desalination plants around the world.


Currently, the most common methods of desalination of sea water are reverse osmosis filters for cleaning, as well as distillation. Freezing and electrodialysis are considered less popular methods.

Desalination at home

The easiest way to purify water at home is to use water filters. With their help, water is purified from harmful impurities and salts. However, household filters are not able to purify water from all harmful substances. Before you purchase and install a filter, you need to get accurate information about what quality water comes from the water supply. You will also need to consult a competent specialist who will advise which filter will be required, taking into account the needs, capabilities and initial quality of the water.

Desalination at home

Everyone knows the benefits of melt water for human health. At home, it is very simple to cook. Glass or plastic containers with tap water, and even better, well water, closed with plastic covers are placed in the freezer. After the water freezes by a third, water that is not frozen must be drained - just all the harmful substances and salts remain in it. The ice should melt at room temperature, and this melt water should be drunk.

Another simple method to get rid of harmful substances in water is to simply boil it. Boil water for at least 5 minutes, and it should be cooled in a sealed container.

Urgency of the problem

If water contains up to one gram of salt per liter, it is already suitable for use in limited quantity. However, if this indicator approaches the ratio of ten grams per liter, such a liquid can no longer be drunk. There are also a number of restrictions for drinking water regarding the content of microorganisms and organic components in it. Thus, obtaining pure liquid is a rather complex multi-level process.

The most popular way to get drinking water is desalination. Moreover, this method is relevant not only for regions with an arid climate, but also for Europe and America. Getting fresh water from salt water is the best way to solve the problem.

A variety of fluid deposits with a high salt content can be found in almost any region of the planet. They lack the conditions for the propagation of microorganisms. Brines occur at a relatively large depth, which eliminates the occurrence of external pollution by hazardous chemical elements. You can also get fresh water from the sea. In this article we will consider the most popular ways to solve this problem.

Boiling water distillation

This technique was used in antiquity. Nowadays, several distillation options are used. The bottom line is to bring the liquid to a boil, and condense the vapor. The result is desalinated water.

To produce a significant amount of liquid, two popular technologies are used. One of them is called multi-column distillation. The essence of the technology is to bring the liquid to a boiling state in the first column. The resulting steam is used to transfer heat to the remaining columns. This technique is effective. With its help, you can get fresh water on an industrial scale. However, this technology is very energy intensive. Therefore, in our time it is used quite rarely.

Instant boiling distillation was recognized as more effective. The essence of the technology is the evaporation of salt water in special chambers. In them, the pressure indicator is gradually reduced. Accordingly, to obtain water vapor, a lower temperature indicator is needed. That is why this technology is more efficient.

There are two more distillation techniques: membrane and compression. They arose as a result of the modernization of the first two technologies. Membrane distillation is based on the use of a hydrophobic type membrane, which serves as a cooling coil. It retains water while letting steam pass through. Compression distillation is based on the use of compressed (superheated) steam in the first column.

All of these technologies have the same drawback. They are too energy consuming. To heat the liquid from zero to one hundred degrees, you need to spend four hundred and twenty kilojoules. And to change the state of water from liquid to gaseous, it will already take two thousand two hundred and sixty kilojoules. Equipment operating on the principle of the technologies considered consumes from three and a half or more kilowatts per hour per one cubic meter of desalinated liquid produced.

Distillation by the sun

In southern countries, solar energy is used to carry out the distillation process. This can significantly reduce the cost of desalination of salt water. To perform the distillation process, you can use solar panels or directly the thermal energy of the sun. The most simple in technical terms is the technology based on evaporators. The latter are special prisms made of glass or plastic into which salt liquid is poured.

As a result, solar energy raises the temperature of water. The liquid begins to evaporate and precipitates in the form of condensation on the walls. Drops emerging from the steam flow into special receivers. As you can see, the technology is very simple. Of its minuses, it is worth highlighting a low coefficient of efficiency. It does not exceed fifty percent. Therefore, this technology is used only in poor regions. With its help, you can provide fresh water in the best case, a small village.

Many engineers continue to work to modernize the technology under consideration. Their main goal is to increase the return on such systems. For example, the use of capillary films can significantly improve the performance of solar distillers.

Note that systems operating from alternative energy sources are not the main tool in obtaining fresh water. Although, their use does not require significant costs for the implementation of the distillation process.

To remove salts from the liquid, other technical solutions can be applied. A fairly popular way of treating water is electrodialysis. To implement the method, a pair of membranes is used. One of them is necessary for the passage of cations, and the second is used exclusively for anions. Particles are distributed across the membranes under the influence of direct current. A similar solution is often implemented in conjunction with solar and wind generators.

Reverse osmosis

Desalination technologies are constantly being improved. Nowadays, techniques based on reverse osmosis are gaining more and more popularity. The bottom line is the use of a semi-permeable membrane. A salty liquid passes through it. As a result, particles of salt impurities remain on the side where the pressure indicator is excessive.

The reverse osmosis method is the most economical. Especially if it is used for desalination of water with an uncritical salt content. In this case, one kilowatt-hour of energy can be enough to get one cubic meter of water. Therefore, reverse osmosis technology is considered the most promising.

Each desalination method has its own characteristics. In order to produce fresh water on an industrial scale, it is necessary to select the most economical and effective option. The reverse osmosis method is by far the most effective.

Existing Desalination Methods

In some regions of the planet, the shortage of fresh water is most pronounced - usually these are arid landscapes. In this area, industrial desalination is used.

At home, it is forced to produce desalinated salt water from harsh living conditions, temporary or permanent, when the population suffers from an acute shortage of moisture suitable for drinking.

Skills on how to make drinking water, having only sea water, more than once saved lives in the conditions of natural disasters, fishermen lost in the sea, as well as extreme travelers.

  • Industrial desalination methods - chemical using reagents, industrial distillation in a distiller, ion using a plant and ion exchanger, reverse osmosis through membrane filters, electrodialysis and industrial freezing,
  • Home desalination methods - distillation and partial freezing,
  • Extreme desalination methods are condensate collection using fire or the sun, as well as fresh ice melting.

Desalination methods on an industrial scale are not our topic, but the options, like at home or in nature to get moisture that is quite suitable for drinking, will be described in more detail - they can be useful.

Desalination in extreme conditions

To get hold of drinking water, having abundance of sea, in extreme conditions, when there are kilometers to a natural fresh spring, is a matter of survival.

The quickest option is to build a primitive distiller at the stake.

  • To do this, put a container filled with sea water on the fire and cover it with a lid.
  • It is advisable to make a hole in the lid and insert a pipe taking off the steam there.
  • If there is no hole and there is nothing to punch it, then the tube is simply clamped by a lid.
  • The other end of the tube, along which the condensate drops will drain, must be lowered into a clean bowl.
  • To speed up the steam escape, the tube is covered with a wet cloth or constantly watered with cold sea water.
  • In the absence of a lid from the dishes, a “roof” is constructed under a slope of metal, and a clean vessel is inserted to the lowest edge where the distillate will drain.

If it happens in the summer heat - there is a very simple option to desalinate water, but in time it will not be as fast as using fire. To do this, you will need only one container, a film and a dug hole.

  • You need to dig a hole a little deeper than the height of your tank.
  • The bottom of the pit is abundantly watered with sea water.
  • An empty container is placed in the center of the recess.
  • The pit is completely covered with a film, and its edges are tightly fixed by sand, pebbles, and earth.
  • A load is placed on the center of the film, directly above the dish — a pebble, a stick, a lump of soil or a handful of sand to make the coating concave.
  • The water, evaporating, will begin to settle on the roof of the film and drain down the slope straight into the placed container.
  • In the heat, in a couple of hours, enough water will collect in the vessel to get drunk.

Note! Condensate is completely devoid of salts, so in order to quench your thirst faster, experienced extreme people advise adding a little sea water.

Another way to desalinate is freezing, suitable for harsh winter conditions. Its algorithm is similar to home freezing, only street frost will act as a freezer here. You need to scoop up sea water and wait for the appearance of ice crystals on the surface - they will taste fresh, and it is quite possible to get drunk with such water.