— What methods of water filtration exist in the world?

— Three groups can be distinguished.

The first is mechanical filtration through meshes and porous structures, such as sponges. Using such methods, you can remove from water any types of particles that are not dissolved in it: sand, rust, scale (formed by oxidation of the metal surface. – “Gazeta.Ru”), clay.

The second is sorption. A substance is poured into the filter, which, through chemical interaction, “binds” harmful particles and does not allow them to pass further. For example, activated carbon.

The third is reverse osmosis technology. Imagine an auger juicer. You put fruit in it, and juice flows in one direction and pulp in the other. This filter is also designed. In it, water is divided into two streams: clean and dirty.

— Is clean water separated from contaminated water mechanically?

– No, this is an electrostatic method. The filter has a membrane that allows only water molecules to pass through, trapping all kinds of impurities. Water molecules have no charge. The main contaminants that we have in our water are positively charged cations and negatively charged anions. You apply pressurized water to the membrane. The membrane repels particles that have a charge, but allows water to pass through.

— What other methods of water filtration exist?

— There are biological and chemical treatment.

During biological treatment, bacteria are added to the water, which eat harmful substances, leaving the water clean. Over time, they die and activated sludge is formed. This method is used at wastewater treatment plants.

Chemical refining is the addition of a chemical, such as a coagulant or flocculant. They bind contaminants and precipitate, after which we filter it or settle the water.

— There are also ultraviolet lamps for water purification. How do they work?

— They disinfect, but do not clean. The composition of water does not change when illuminated with a UV lamp.

— How is drinking water prepared in the city?

— The method of purifying city tap water depends on the source liquid.

But often this method is supplemented with chemical cleaning using coagulants and flocculants. Sometimes ozonation, the addition of powdered activated carbon, or membrane cleaning are used.

— At what stage is chlorine added to water?

– It is always used at the very end.

— And what is the final composition of such water?

— We removed some large particles and organic matter from this water. But its salt composition has not changed. There was as much salt as there was left.

— Is this how the water comes into the tap?

— While the water reaches the tap, it “catches” the so-called secondary pollution. Often these are iron impurities or manganese, if it is contained in water pipes.

In addition, water can “catch” some microbiology, because bacteria can grow in old pipes.

But they will die along the way, since chlorine is added to the water.

— How much chlorine is usually added to water?

— When you open the tap at home, the water contains from 0.3 to 0.5 mg per liter of active chlorine. At the water treatment plant, it is added in such a way that after the water has passed through all the pipes, chlorine will still remain at the outlet. It is known to evaporate from water over time.

— Is active chlorine harmful?

– Certainly. First of all, it smells bad. Secondly, it is active and can enter into chemical reactions. If your outlet water is clean, you do not have any microorganisms or organic residues, then it will simply evaporate over time.

But, if you have some other substances in your water – for example, you poured water from the tap and started preparing broth with it, active chlorine will begin to enter into chemical reactions with substances from the water. Then no one knows what the outcome will be.

– Isn’t chlorine removed by boiling?

“The question is what will happen first: it will evaporate or it will interact.”

— Is rust also harmful to the body?

– It’s just a particle that is insoluble in water. This is more unpleasant than harmful. You ate the pebble, it passed through you and came out, nothing happened to you.

— From the point of view of salts, the problem is the most difficult. Because you need to keep the good and remove the bad.

There are useful salts – sodium and potassium. Our body needs them, they are needed for blood, which itself is a saline solution. This is why distilled water is not very useful. Such water always needs to be further enriched. There are borderline calcium salts and magnesium. The body also needs them for the functioning of the heart and muscles, but in small doses.

The hardness of the water depends on their quantity: if you see a large amount of scale on the kettle, then exactly the same formations will be inside your body. These are kidney or gallstones.

And there are harmful salts of iron, manganese, lead, copper, nickel and heavy metals. They definitely need to be removed.

— We are discussing tap water. What about well water and water from wells?

— The city water utility analyzes water daily for a very large number of indicators, about 40-50 of them, so we always know the approximate composition of the water. And in the well there will be mechanical and organic contaminants, salts, and dissolved gases.

I have been working with water for 20 years and during this time I have seen, it seems to me, everything: wells with arsenic, boron, non-ferrous metals, radioactivity. It is important at the initial stage, after starting the well, to test the water for the maximum number of indicators.

— And if you boil water, can you not filter it?

– Let’s figure out what happens when water boils. First, boiling water releases chlorine. But if you had any organic contaminants there, they remained there, and they could interact with this chlorine before it was all removed.

Secondly, scale has fallen out, that is, the salt composition has partially adjusted and the hardness of the water has decreased. But nothing will happen to heavy metals and dissolved iron. Therefore, it is better to filter the water.

— What filters are currently available on the Russian market?

— There are three large groups: jug filters, under-sink filters with three flasks and reverse osmosis filters.

If we talk about the differences, then the jug is cheaper, you can take it to the dacha, but the cassette must be changed often and wait until the water is filtered. Three-stage ones are more expensive, they are connected to the system, but the cartridges can be changed less often – one can work from six months to a year, plus you don’t have to wait for the water to be filtered.

Still others are significantly more expensive, take up more space under the sink, and have a complicated installation process, as they require a connection to the drainage. But they can purify almost any water. Here you can sleep peacefully, if upstream of your city there is a chemical plant that opened the valves at night and threw something into the water that the water utility could not even imagine – it will not end up in your tap. Osmosis will clean everything, guaranteed.

— Does this also apply to wells?

— This filter cannot be installed on the entire private house. Reverse osmosis quadruples water consumption. The water is divided into two streams, only 20% of the water becomes clean and ends up in the tap, the remaining 80% is water along with contaminants, and it goes into the drainage.

In addition, reverse osmosis is an antibiotic in the field of water filters. This is a powerful remedy that can help in the most severe cases. It can purify water where conventional filters cannot. But using it has a number of side effects.

— If there is a well on the property and you don’t know what’s in the water, is it logical to install reverse osmosis?

— First you need to do a detailed water analysis. There are cases when you have opened a well, and nothing can be done with it, just look for another source of water. Radioactivity is one of those cases. There is also very high hardness when you actually have semi-sea water flowing from your well. It is also difficult to deal with clay. It is so fine that it penetrates everywhere and very quickly clogs any cleaning system. Especially if the water contains white clay – kaolin.

— How then to arrange filtration in the cottage?

— You have a well, you have done a water analysis, and then, depending on its results, a filtration system is selected. The fundamental difference between a house and an apartment is that the volume of water is much larger. Therefore, the system is designed so as not to change filters. They provide a regeneration system: washing the filter and restoring its filtering ability.

Slightly different principles and hardware design are used, and an automatic control unit appears. He knows how much water has been filtered, and he knows that the regeneration process doesn’t need to start while the whole family is sitting at dinner, so he does it at night.

— Is it possible to somehow improve the water, make it healthier?

– Yes. Instead of drinking dietary supplements and vitamins, we can mineralize water using filters.

The fact is that when you take vitamins, you absorb approximately 10 to 50% of the nutrients. In addition, at the moment of taking the pill, the amount of substances in the body jumps sharply and then falls. None of this is very good.

You can make the filter dose the amount of useful substances, and you would receive them with water constantly.

– How to do it?

— There are filters on the Russian market that can dose magnesium, zinc, and silicates. Of course, you cannot add the entire composition of vitamins to water, but some microelements, yes.

— What can you say about the so-called hydrogen water?

— Until scientific results are shown to me, I will not believe in the benefits of hydrogen water.

— Alkaline water activators are also sold. Are they needed?

— Alkaline water has a pH above average and a certain redox potential. It is possible to increase the pH of water, but we have doubts about the restoration potential. We experimented quite a lot with alkaline water, and we were unable to prove its beneficial properties.

— What can you say about water ionizers, which are also sold?

— There are ionizers, there are so-called structurers, but all this has not been scientifically proven. For example, you can check the properties of a filter and demonstrate them, measure how much water it filters, how well it does it, over what period of time. In the case of ionizers and structurers, the properties cannot be checked. Therefore, it is better to purchase those devices whose effectiveness has been proven.