So that you can imagine how much and what kind of water is available on our planet, I bring to your attention a table. 2.1. We have so much water that measuring it in liters, cubic meters or tons is extremely inconvenient, and we will use a truly titanic measure - a cubic kilometer (km?). The total water on Earth is about one and a half billion, or 1500 million km? water.

Table 2.1. Distribution of waters on the globe (unit of measurement – ​​million cubic kilometers)

Note. The data in the table is given by minimum and maximum, taking into account different estimates.

So, we see that fresh water, that is, water on land and in the atmosphere, makes up about 10% of the total planetary resource. Most of them - and this may come as a surprise - are located not in open bodies of water, but in the earth's crust: 110–190 million km?! These waters are usually divided into two types according to their depth. Deep underground waters are located tens to hundreds of meters from the surface of the earth, they permeate porous rocks, and also form giant underground pools surrounded by waterproof layers. Often the water in these underground cavities is under pressure, and if you break through to them with a drilling rig, the water will spray upward in a fountain. Such fountains, geysers and springs natural origin well known.

Another type of groundwater is those that are located in the soil and upper layers the earth's surface at a depth of several meters. Compared to deep waters, they have one disadvantage and one advantage. Flaw: these waters are much more actively in contact with the surface of the earth and everything that is poured onto it, thrown out or buried in it; they are much less protected from pollution than deep waters. Advantage: these waters are much more accessible to us, they appear in any hole or ditch, and we can draw them from wells.

The next largest body of fresh water (20–30 million km?) is concentrated in the glaciers of Antarctica, Greenland and the North Islands Arctic Ocean. We receive fresh water from the atmosphere (only 13 thousand km?) in the form of precipitation - rain and snow. The main supply of fresh water consumed by humans is concentrated in lakes and rivers, and it must be taken into account that, although rivers are longer than lakes, their volume is much smaller. Living organisms, that is, plants and animals (which, let me remind you, are two-thirds water), contain 6 thousand km? water – a value quite comparable to the volume of rivers. The latter should not be surprising: the one-time volume of rivers is static, but if we consider the dynamics, then only the rivers of Russia transfer 4 thousand km to the ocean per year? water.

This is how water resources are distributed on our planet. Having analyzed the table data, we can conclude that for drinking, domestic and industrial needs, primarily the waters of lakes and rivers that supply us are more accessible fresh water not from time to time, but constantly and with a guarantee. In addition, we can easily evaluate these reserves and compare them with our current and future needs.

Both types of groundwater are also available. However, there is not enough groundwater for large cities. In principle, it is possible to explore large deep basins and drill wells, but this is expensive. Besides, who guarantees that such a pool will be found near a populated industrial city? Will the water in it be suitable for drinking, and will there be a geological disaster if we start withdrawing this water in large quantities?

Precipitation, that is, rain and snow, is also a source of fresh water. But this is an intermittent, capricious source that mainly satisfies the needs of agriculture.

This means that there are still rivers and lakes, and at the same time rivers are more convenient for us than lakes: there is less water in them, but, as I already mentioned, they are much longer. In fact, most of our civilization is concentrated in river valleys - a circumstance that has remained unchanged since the times of Ancient Egypt, Akkad and Sumer.

Types of fresh water

Before moving on to considering the types of fresh water, let us dwell on their main purpose: they are a source of quenching thirst. When it hits us, we can't think about anything but water. Then any fresh water - be it from a dirty river or a puddle - becomes drinkable for us. If we cannot satisfy our thirst within a few days, we will die. The number of days is determined by the weather and climate: hot, dry or humid.

We, like any animals, are in a state of continuous water exchange with the environment: we secrete sweat and urine and replenish water losses with fresh moisture. If it is not possible to get drunk, then water is lost through sweat and exhaled air, and as a result, there is a threat of dehydration (dehydration) of the body. At the first stage, the pulse quickens, weakness occurs, then dizziness and shortness of breath. With dehydration of only 10% of body weight, speech, vision and hearing impairments will occur, followed by delirium, hallucinations and loss of consciousness. Death occurs from irreversible changes in the nervous and cardiovascular systems with water loss of 15–25% of body weight (depending on temperature environment).

Such is death from thirst, and it is all the more tragic when it occurs at sea or in an ocean full of water - but salty! However, many probably remember the journey of Alain Bombard, a French explorer who swam across Atlantic Ocean in an inflatable boat and quenched your thirst sea ​​water and juice squeezed out of fish. Is this possible? As an exception - yes! But only as an exception, as a way to save your life in extreme situation, because we cannot drink salt water for a long time.

Calcium sulfate and carbonate, magnesium chloride, sulfate and bromide are present in sea and ocean water, but in small quantities. Almost 85% of sea and ocean salts are sodium chloride, common table salt. The saturation of water with salts varies in different seas and oceans. I experienced this firsthand when swimming in the Baltic, Black and Mediterranean seas. The Gulf of Finland is almost freshwater: 1 liter of its water contains 3–4 g of salts, in the Black Sea – 15–18 g/l, in the ocean – up to 35 g/l, and, for example, in the Red Sea – 40 g/l. Swimming is comfortable, but drinking is not allowed. A person vitally needs salts of potassium, sodium, magnesium, calcium and other elements, but in moderate doses. We cannot drink water with a salt content of more than 2.5 g/l.

Why? To maintain salt balance in the body, a person needs 15–25 g of salt per day - mainly NaCl, which we get from food. If there is excess salt, it is excreted in the urine through the kidneys, but to remove one extra gram of salt you need to drink 100 g of water.

Well, now are you convinced that without water, as the song says, “you can’t go there and you can’t go here”? Just need to clarify - without fresh water.

In Chapter 1, I mentioned that fresh water can be divided into two groups: regular And mineral. Moreover, within each group, water differs greatly in composition due to geological and geographical reasons. This classification is valid for waters of natural origin, but, in addition to them, there are artificial waters, man-made purposefully or as waste from economic activities. We purposefully produce artificial mineral waters, desalinated water (from sea water) and distilled water, as well as special waters saturated with one or another component, for example silver. As for liquid waste, they are called drains, discharges and wastewater. Of course waste water cannot be classified as either fresh or salty marine, but within the framework of this book we need to get acquainted with them. So, if we take into account all these groups of waters, then our primary classification will be more or less complete. Let's start with distilled water.

Distilled water

Distilled water- this is pure H?O, or more precisely, water with insignificant, practically undetectable by chemical and physical methods impurities of foreign substances. It is used only for medical or research purposes, for example, to wash test tubes for conducting fine tests. chemical experiments. It is produced by evaporating ordinary fresh water followed by condensation of the steam. We can do the same with sea water to rid it of salts and mineral inclusions. Distilled water can be produced at home by making a homemade distiller or purchasing a special installation. But I don’t advise you to do this - distilled water is completely useless for us: it does not support vital important processes in the human and animal body. As has been mentioned more than once, the drinking water we need is not a perfectly pure substrate, but a solution containing mineral supplements. These additives - iron, copper, sodium salts, potassium, calcium and other elements - the main point. If we do not get them in the required quantity through water, various functional disorders will arise: heart rhythm disturbances, headaches, muscle cramps, as well as problems with teeth and bone tissue. In a word, distilled water, which does not contain salts, can unbalance the functioning of our body.

They drink distilled water, compensating for the lack of necessary substances in it with a special diet, raw food diet, vegetables, fruits, micronutrient preparations, etc. This is exactly the option proposed worldwide famous nutritionist Paul Bragg. Today, this idea has become even more constructive: for example, in the West, companies have appeared that supply distilled water for drinking, and to accompany it - tablets with a full range of vital minerals. I drank some water with a tablet - and eat as you want, without any diets.

However, let's not experiment, let's obey nature and drink the water of rivers, lakes and springs - the water that our ancestors drank. Just first we clean it of all rubbish.

Regular fresh water

As already mentioned, the fresh waters of rivers and lakes, our main source of water supply, are different. These differences arose initially and are associated with climatic zone and the characteristics of the area in which the reservoir is located. Water is a universal solvent, which means that its saturation with minerals depends on the soil and the underlying rocks. In addition, water is mobile, and therefore its composition is affected by precipitation, snowmelt, floods and tributaries flowing into a larger river or lake. Take, for example, the Neva, the main source of drinking water in St. Petersburg: it is mainly fed by Lake Ladoga, one of the freshest lakes in the world. Ladoga water contains few calcium and magnesium salts, which makes it very soft, it contains little aluminum, manganese and nickel, but quite a lot of nitrogen, oxygen, silicon, and phosphorus. Finally, the microbiological composition of water depends on aquatic flora and fauna, from forests and meadows on the banks of a reservoir and from many other reasons, not excluding cosmic factors. Thus, the pathogenicity of microbes increases sharply in the years solar activity: previously almost harmless ones become dangerous, and dangerous ones become downright deadly.

I, a third-generation Petersburger, drank fresh water from the Dnieper and Volga, from the Don and Kuban, drank water in Moscow, Norilsk, Irkutsk, Vladivostok, Prague, New York, Berlin and many other places, but all this water was for with the exception, perhaps, of the water on the southern coast of Crimea, it seemed unusual and tasteless to me. Is this a coincidence? Apparently not. Our body is adapted to the water of our homeland, it permeates, shapes us, and there is nothing tastier or sweeter, but on the condition that it is clean.

The concept of purity, if we remember the diversity of fresh waters, is actually very ambiguous. (The next chapter will provide Russian and foreign standards for drinking water.) There are several important indicators of the quality of fresh natural water: acidity pH (or pH value), rigidity And organoleptics.

pH is related to the concentration of hydrogen ions in the medium, is measured using a simple pH meter and gives us an idea of acidic or alkaline properties of the medium (in this case, water):

pH< 7 – кислая среда;

pH = 7 – neutral environment;

pH > 7 – alkaline environment.

This is a very important indicator, not only for ordinary or mineral water, but also for the human body, the acid balance of which must be maintained within very strict limits: permissible pH values ​​range from 7.38 to 7.42 and cannot deviate even by 10%. from this range. At pH = 7.05, a person falls into a pre-comatose state, at pH = 7.00, coma occurs, and at pH = 6.80, death occurs.

Rigidity is a property of water determined by the content of calcium ions Ca 2+ and magnesium Mg 2+ in it. Hardness is determined using a special method described in GOSTs for drinking water, and its units of measurement are moles per cubic meter (mol/m3) or millimoles per liter (mmol/l).

There are several types of hardness - general, carbonate, non-carbonate, removable and irremovable; in the future we will talk about overall hardness, associated with the sum of the concentrations of calcium and magnesium ions.

Under organoleptic The characteristics of water include its smell, taste, color and turbidity. Smell determined by sniffing the water (earthy, chlorine, petroleum odor, etc.) and rating the intensity of the odor on a five-point scale (zero corresponds to complete absence smell):

1 – very weak, almost imperceptible odor;

2 – the smell is weak, noticeable only if you pay attention to it;

3 – the smell is easily noticed and causes disapproval of the water;

4 – the smell is distinct, attracts attention and makes you refrain from drinking;

5 – the smell is so strong that it makes the water unfit for consumption.

Taste water is characterized by the definitions salty, sour, sweet, bitter, and all other taste sensations are called flavors. Taste is assessed on the same five-point scale as smell, with gradations: very weak, weak, noticeable, distinct, very strong. Color water is determined photometrically, by comparing the test water with standard solutions that imitate the color of natural water. Color is assessed using a special chromaticity scale with gradations from zero to 14. They examine in a similar way turbidity.

Of course, the causes of foul odor, bad taste and strange color in water are studied using chemical analysis methods to identify harmful impurities and determine their concentrations. To complete this topic, let me remind you that each such impurity has its own MPC - maximum permissible concentration, that is, one that does not harm our body. Of course, there are substances, viruses and bacteria for which the MPC is zero, that is, they should not be in the water at all. But this is not a mathematical, but a “practical” zero - harmful substances and microflora may be present, but in such an insignificant concentration that they cannot be determined by the most subtle and accurate methods of analysis.

In addition to lakes and rivers, we get regular fresh water from wells, artesian wells, springs, as well as by collecting precipitation, filling buckets and barrels with rainwater, or melting ice and snow. Let's talk about the first three types of water.

Well water. Wells are actually used only in rural areas, since a pit with a depth of 5-10 m is not capable of providing a large output of water - for this it is necessary to drill wells at 20-180 m, depending on the depth of groundwater. Wells are fed by groundwater and can provide water consumption of up to 100–150 l/h (in rare cases, up to 500 l/h). They are very vulnerable to contamination: everything that gets into the soil - nitrates, nitrites, surfactants, pesticides and heavy metals - can end up in well water.

Water from artesian wells. As I have already noted, deep waters are better protected from various industrial and bacterial pollution, but in the city it is difficult to use such waters: firstly, you need to find them, and secondly, drill a well. This expensive pleasure: special installations are used for drilling, then steel pipes are lowered into the well, a powerful pump is immersed, and a pipeline is brought to the surface from it. In the central regions of Russia there are two aquifers: the sandy one lies at a depth of 15–40 m and is separated from the top layer of soil by clay layers, which protect it from pollution, and at a depth of 30–230 m or more there are limestone aquifers, the so-called artesian. This is how much you need to drill, and then, when you get to the water, check whether it is good and does not require cleaning. It is known that the composition of artesian waters depends on their depth. Such water may have increased hardness and contain bacteria and organic matter. In addition, due to poor connections of pipes in wells, contaminants from higher levels can leak into artesian water. aquifers. Typically this water needs to be filtered and purified, which is done using industrial rather than domestic purification systems.

Spring and spring water. Under the spring, or key, in contrast to a stream, river and river, is understood to be a small stream of water flowing directly from the bowels of the earth. It is appropriate to recall that some of our rivers are generated by mountain snows and glaciers, and some by just such underground sources. However, at a considerable distance from them, river water can no longer be recognized as spring water. Spring moisture is taken from the very place where it comes from underground. Water can be fresh or mineralized. In the first case, we are, in fact, talking about springs and springs, and in the second, about a source of mineral waters.

The nature of spring water is the same as that of well or artesian water, since it comes from some kind of underground aquifer or pool.

There are an innumerable number of springs on the territory of Russia; they differ in the quality and composition of their waters. There are legends about the springs - and many of the waters actually have healing properties, they are fresh and pleasant to the taste. But springs, just like artesian wells and wells, are susceptible to pollution. Nowadays, it is impossible to guarantee the constant quality of spring water, since it depends not only on seasonal circumstances (rainfalls, floods), but also on emissions from nearby industrial enterprises.

For example, spring water within the city limits of Nizhny Novgorod was declared unsuitable for drinking, of which the local sanitary and epidemiological inspection officially notified the population. Studies have shown that the poor location and poor amenities of springs, insecurity groundwater from surface pollution are the causes of poor water quality. In the springs located near Blagoveshchensk and Pechersky monasteries, Vysokovskaya Church, Pokhvalinsky Congress, the nitrate content exceeds acceptable standards 1.5–3 times, and microbiological contamination significantly exceeds the maximum permissible concentration. Naturally, the sanitary service prohibited the use of such water.

The situation is similar in other cities. There are only a few springs left in Moscow from which you can drink water: the spring “Sergius of Radonezh” in Teply Stan, “Saint” in Krylatskoye, “The Swan Princess” in Pokrovsky-Streshnevo, “Tsaritsyno” in the floodplain of the Tsaritsynsky pond. Some popular springs from ancient times were closed: the water of the spring in Troparevo Park exceeded the maximum permissible concentration for chromium, in the Filevsky spring - for aluminum, potassium, magnesium, in the spring of the Life-Giving Trinity in Borisov - an excess of iron, in the springs in Sviblovo (in the Yauza floodplain) and " Kadochka" (in Kolomenskoye) exceeded the maximum permissible concentration for heavy metals, and in "Beket" in Donskoy - for cadmium and chromium. All these springs were well-known and popular, they were used (and, despite the ban, still continue to be used) by hundreds of residents, and therefore there were initiators of such checks. But somewhere in the outback they still draw water from their great-grandfather’s springs, which have long been clogged, and only medical and environmental studies can reveal the connection between poor water quality and the increase in the number of people suffering from urolithiasis, diseases of the digestive tract and the cardiovascular system.

Currently, bottled water, both spring and mineral, is sold in cities. For example, in St. Petersburg one of the largest suppliers of such water is joint stock company"Polyustrovo". I would like to hope that the springs and wells from which this water is taken are located away from city underground communications, all kinds of landfills and other sources of contamination, and that the composition of the water is regularly monitored by the sanitary service. I would also like to hope for the integrity of the suppliers of spring and mineral water and to be sure that they are not selling us tap water that has been passed through a Geyser or Aquaphor filter. After all, if there is fake vodka, why shouldn't bottled water be fake?

Mineral water

Natural water with a high content of mineral components is classified into four groups.

1. Mineral medicinal waters with a total mineralization of more than 8 g/l. This also includes less mineralized water containing increased amounts of boron, arsenic and other elements. It is taken only as prescribed by a doctor.

2. Mineral medicinal table waters with a total mineralization of 2–8 g/l. They are used for medicinal purposes as prescribed by a doctor, but they can be used as a table drink.

3. Mineral table waters with a mineralization of 1–2 g/l.

4. Table waters with mineralization less than 1 g/l.

Mineral waters, as a rule, owe their origin to underground aquifers or pools located among special rocks, which over a long period enrich the water with healing minerals, which dissociate in solution into positively charged cations and negatively charged anions.

The names of waters may include the definitions “bicarbonate” and “sodium”, which means that these substances are the most abundant, but there may be waters of chloride-sodium-calcium, chloride-sulfate, sodium-magnesium, etc. Depending on what indicator the water has pH (that is, which charge ions predominate), mineral water is acidic, neutral or alkaline. The effect of each on the gastrointestinal tract and the body as a whole will be different. ABOUT medicinal properties Quite a lot has been written about these waters, about what diseases and how they should be taken, and for this information I will refer readers to specialized literature. For example, to great article G.Z. Store "Use of mineral waters at home", published in the collection.

Artificial waters

Under artificial I understand fresh waters produced with the help of certain technological tricks with the goal of either copying what nature has produced, or creating something that has no analogue in nature. Desalinated seawater, which is produced on a large scale by the United Arab Emirates, which is rich in oil but poor in fresh water, can also be considered artificial, as can heavy water obtained for research in the field. nuclear physics, but we will not dwell on this subject. You can make an artificial one mineral water or fake it, but this also does not interest us too much: we will turn to water with miraculous properties - melted water, shungite, silver, “living” and “dead”. And when we look, we find out that in this area there is truth, half-truths and whole piles of fantasies and lies.

Melt water. Of course, you can get it by melting snow or ice in a saucepan, but I do not recommend doing this, especially for city residents. There is such a compound - benzo(a)pyrene, a carcinogenic organic compound of the first hazard class (carcinogenic - that is, leading to cancer diseases). The main sources of environmental pollution with benzo(a)pyrene are aluminum production and transport aerosols (simply car exhaust gases). As studies by ecologists have shown, in dust and snow on the street or next to a suburban highway, the amount of benzo(a)pyrene is tens of times higher than the maximum permissible concentration. Melting water from such snow is like pouring potassium cyanide into tea instead of sugar. Natural melt waters will wash it into water bodies, and there it will be diluted to such an insignificant concentration that it cannot be detected with the help of the most sophisticated tests. But it’s better not to touch the snow near the roads.

The home method of preparing thawed, or frozen-thawed, water is described in Appendix 1. Once you familiarize yourself with it, you will see that this technology helps purify drinking water from some harmful impurities and, possibly, imparts beneficial properties to it. The question, however, is that useful macro- and microelements can be lost along with heavy metals.

Shungite water. Shungite- a rock, vast deposits of which are available in the area of ​​Lake Onega, and in these deposits water circulates and seeps to the surface, saturated with healing shungite emanation. Peter I built the first hydropathic clinic in Russia in these places, and it still exists today - the Marcial Waters resort near Petrozavodsk. There is a sanatorium where people are treated with water very rich in iron.

But how effective is artificial shungite water, which is prepared using household shungite filters? The filter is small in size, the water is in short-term contact with the mineral substance. Moreover, this contact is by no means of the same quality that is realized in nature. Does water have time – and can it, in principle – become healing? Big question! As for its purification from harmful impurities, there are even more questions.

In the book by O.A. Rysyev “Shungite – a stone of health”, it is reported that St. Petersburg enterprises producing shungite filters also produce magical pyramids from shungite, the so-called “Pharaoh’s rods”, bags filled with shungite, which must be placed under the bed to protect themselves from the harmful influence of geopathogenic zones. A map of the zones is attached, and judging by it, the residents of St. Petersburg do not have long to live - of course, if shungite does not save them. Such tales cause distrust in both artificial shungite water and shungite filters. But if you love curiosities and miracles, then read Rysyev’s book, as well as another one by Yu. Doronina, “Shungite – the Savior Stone.” But it is still better to purchase an “Aquaphor”, “geyser” or “barrier” filter. Firms with a narrow specialization that produce only filters, without any magic rods and pyramids, are more trustworthy.

Silver water. You can read about its properties in a number of books and publications (see, for example,). In our list of artificial waters, it inspires the most confidence, since the bactericidal properties of silver have been known since ancient times. Back in Ancient India This metal was used to disinfect water, and Persian king Cyrus stored water in silver vessels. The bactericidal properties of silver have also been confirmed by modern science.

The pioneer of research in this area is considered to be the French physician Besnier Crede, who at the end of the 19th century reported success in the treatment of sepsis with silver ions. Continuing his research, he found out that silver kills diphtheria bacillus within three days, staphylococci within two days, and the causative agent of typhus within a day. At that time, Crede's results created a sensation in the scientific world and attracted attention to this method of healing ailments.

In 1942, the Englishman R. Benton managed to stop the epidemic of cholera and dysentery that raged during the construction of the Burma-Assam road. Benton established a supply of clean drinking water to the workers (there were 30 thousand people), disinfected using electrolytic dissolution of silver (concentration 0.01 mg/l). Of course, other means were used for this, but it is believed that the use of silver water played a decisive role.

When the bactericidal properties of silver were studied, it turned out that the decisive role here is played not by atoms, but by positively charged Ag + ions. (Let me remind readers that ionization, discussed in Chapter 1, increases the activity of substances in aqueous solutions.) Silver cations suppress the activity of the enzyme that ensures oxygen metabolism in the simplest microorganisms, in other words, they “strangle” pathogenic bacteria, viruses, fungi (in this “deadly » list of about 700 species of pathogenic “flora” and “fauna”). The rate of destruction depends on the concentration of silver ions in the solution: for example, E. coli dies after 3 minutes at a concentration of 1 mg/l, after 20 minutes at 0.5 mg/l, after 50 minutes at 0.2 mg/l, after 2 hours – at 0.05 mg/l. It was found that the disinfecting ability of silver is higher than that of carbolic acid, sublimate, and even such strong oxidizing agents as chlorine, bleach, and sodium hypochloride. A natural question arises: why do water treatment plants use chlorination, fluoridation and a more modern method - ozonation, and not electrolytic saturation of water with silver ions? This question has an equally logical answer: expensive. Still, silver is a precious metal... In addition, let’s not forget that silver is a heavy metal, and its saturated solutions are not at all useful to humans: the maximum permissible concentration is 0.05 mg/l.

When taking 2 g of silver salts, toxic effects occur, and with a dose of 10 g, death is likely. In addition, if a reasonable dosage is exceeded for several months, the metal may gradually accumulate in the body.

Silver is an important trace element for us, necessary for the normal functioning of the endocrine glands, brain and liver. But I repeat once again: this fact is not a reason to get carried away with drinking silver water with a high concentration of ions.

As for silver water with the above-mentioned ion concentration, it can be drunk regularly and constantly (for example, astronauts drink it while on duty space station). Preparing silver water at home is very difficult. If you infuse water in a silver vessel, the effect will be insignificant. Silver water is produced in special electric ionizers and sold in stores (although there may be doubts about whether it is actually silver). It can also be obtained using the “Penguin” and “Dolphin” installations, which will be described in the fifth chapter.

"Living" and "dead" water. These terms can be understood not only as life-giving and destructive water from Russian folk tales, but also as something more specific.

“Living” and “dead” water were first obtained by the inventor Kratov (see publications), who was healed of adenoma and radiculitis with their help. These liquids are produced using the electrolysis of ordinary water, and sour water, which collects at the positively charged anode, is called “dead”, and alkaline(it concentrates near the negative cathode) – “alive”. Judging by the descriptions in the literature, “living” water is soft, light, with an alkaline taste, sometimes with white sediment; its pH = 10–11 units. “Dead” water is brownish, sour, with a characteristic odor and pH = 4–5 units. The industry is already producing installations for electrolysis at home (“STEL”, productivity up to 60 l/h, and less productive but convenient “Espero-1”). In addition, “living” and “dead” water began to be sold in bottled form in pharmacies and stores.

It is believed that these waters help with various diseases. There are many wonderful and entertaining stories about healing with the help of “living” and “dead” water. But they are reported in very dubious books and even more dubious articles. I'm used to sticking to firmly established facts.

I do not condemn activated water, but I want to warn you: be careful with healing waters, which have not yet been sufficiently tested in practice. Take them only on the recommendation of a doctor, and not from healers, sorcerers and authors of dubious books. Remember that even such harmless water as rainwater can be harmful: it is soft, you can wash your hair in it, but you should not drink it - it contains few of the salts we need. But it is possible that after acid rain, rainwater may contain components that are undesirable for our body.

Wastewater

I want to end this chapter by talking about wastewater. They are neither fresh nor salty. They can be divided into two types: the first come from city apartments, from the city sewerage system, the second - from industrial enterprises. The first type of water contains feces, urine, paper, soap, and food debris. All this settles in water sumps, rots on special sites and does no harm to us or the environment. In addition, wastewater contains elements that natural treatment processes cannot cope with: surfactants; microbes and viruses; medicines.

We take a lot of medications, but not all of them are completely absorbed by the body. Residues are excreted through the gastrointestinal tract and kidneys and end up in wastewater. Antibiotics and analgesics, contraceptives, anti-obesity drugs, steroid hormones - etc., etc. It is still difficult to predict the consequences of this type of pollution. Perhaps now it is not yet particularly dangerous for humans. But what can happen after some time, for example, when antibiotics come into contact with pathogenic bacteria? Either the antibiotics will be stronger, or antibiotic-resistant strains will emerge. The latter promises us big trouble...

Let's not guess, however, and talk about wastewater from enterprises. Of course, we cannot abandon chemical and pulp and paper mills, electroplating shops, metallurgical and engineering plants, nuclear power plants and everything else that saturates water with heavy metals, harmful chemicals and even radioactive isotopes. But we must have an idea about something so that, on the one hand, we do not panic, and on the other, we must exercise the necessary caution. I will list this information point by point.

1. At the moment, tens of thousands of chemical compounds are known to humanity. Once in the water, these substances undergo various changes: they decompose, react with each other, with chlorine or ozone, which disinfects the water, and as a result, new modifications previously unknown to science can be obtained. Relatively few of this huge number of compounds have been studied so thoroughly that one can conclude that they are neutral or, conversely, have a harmful effect on the human body and animals; There are no maximum permissible concentrations for these substances. True, the most dangerous ones have been studied, and we will talk about them in Chapter 3.

2. We should not think that waste water is being supplied to our water supply. Purification of wastewater and preparation of water entering our apartments are two different processes carried out by government authorities. unitary enterprises"Vodokanal", which are in any city. Wastewater is purified at special aeration stations, where it is filtered, settled, saturated with oxygen and only then enters natural reservoirs, and the sludge (dry matter) is disposed of. There are different methods of disposal: burying it in the ground, throwing it into the ocean, transporting it to the territory of another state, or processing it in a special factory. Wastewater purified from dry residues does not chlorinate, at least in our case. The reason is simple: yes, there are a lot of pathogenic bacteria and viruses in this water, but if you kill them with chlorine, then monstrous amounts of chlorine will enter the water bodies, and this is much worse than bacteria. Nature gets along with them, but not with chlorine and its compounds. Fish, animals and people are poisoned.

Treated wastewater, of course, contains harmful substances, but after entering vast natural bodies of water, the concentration of these substances is often diluted to negligible amounts that cannot be detected by the most accurate analytical methods. I’ll immediately add that this does not happen everywhere and not always: for example, in Lake Ladoga and the Neva the situation is relatively favorable, but on the Rhine or Volga it’s a completely different story.

Water is taken from natural reservoirs for domestic consumption (most importantly, for drinking and cooking). This is a completely different operation, not related to wastewater treatment. This is done by the water intake and water treatment stations of Vodokanal. The water goes through the necessary purification stages, is chlorinated or fluoridated, and then enters the water supply network. Possible dangers: poor-quality cleaning, rusty water pipes, volley unauthorized discharge of industrial waste by some enterprise.

3. However, the person is resilient. Our body is able to cope with toxic substances if they are not supplied in too large doses or in small but constant doses. If there is fish in the river from which the water is drawn, then the situation is not yet fatal, but if beavers, who are very sensitive to water quality, appear in the reservoir, things are generally fine. Well, if the sturgeon swam upside down, this is already a crime. Will a household filter help? I highly doubt it.

4. Rivers and lakes have the property of self-cleaning. This is an extremely powerful natural mechanism. However, we cannot be complacent. Monitor your drinking water and, if something goes wrong, sound the alarm!

After two world wars, a mass of German weapons, bombs, explosives, and cylinders with a military agent - mustard gas - were sunk at the bottom of the Baltic Sea. What happens to these “gifts” of the past now, decades later? In the journal “Ecological Chemistry” I read articles by specialists who regularly study the burial area. The bodies of containers and bombs rust, resulting in harmful chemical compounds seep into the bottom waters, and most importantly - mustard gas! But it turns out that there are microorganisms that “eat” mustard gas and convert it into compounds that are safe for living organisms. Now, if all the bombs and containers crumble at once and there is a volley of poison, then these bacteria may die.

However, no one knows what will happen then. We can be sure of only one thing: the millstones of nature rotate slowly but surely, and if we don’t strain it, it will forgive us and save us.

Water is life. And if a person can survive for some time without food, it is almost impossible to do this without water. Since the heyday of mechanical engineering, the production industry, water has become too quickly and without special attention on the part of man to become polluted. Then the first calls about the importance of preserving water resources appeared. And if, in general, there is enough water, then the reserves of fresh water on Earth constitute a negligible fraction of this volume. Let's look into this issue together.

Water: how much is there and in what form does it exist?

Water is an important part of our life. And it is this that makes up most of our planet. Humanity uses this extremely important resource every day: for domestic needs, production needs, agricultural work and much more.

We are used to thinking that water has one state, but in fact it has three forms:

• liquid;
• gas/steam;
• solid state (ice);

In a liquid state, it is found in all water basins on the surface of the Earth (rivers, lakes, seas, oceans) and in the depths of the soil (groundwater). In its solid state we see it in snow and ice. In gaseous form, it appears in the form of clouds of steam.

For these reasons, calculating the amount of fresh water on Earth is problematic. But according to preliminary data, the total volume of water is about 1.386 billion cubic kilometers. Moreover, 97.5% is salt water (undrinkable) and only 2.5% is fresh.

Fresh water reserves on Earth

The largest accumulation of fresh water is concentrated in the glaciers and snows of the Arctic and Antarctica (68.7%). Next comes groundwater (29.9%) and only an incredibly small part (0.26%) is concentrated in rivers and lakes. It is from there that humanity draws the water resources necessary for life.

The global water cycle changes regularly, causing numeric values change also. But in general, the picture looks exactly like this. The main reserves of fresh water on Earth are in glaciers, snow and groundwater; extracting it from these sources is very problematic. Perhaps, not in the distant future, humanity will have to turn its attention to these sources of fresh water.

Where is the most fresh water?

Let's take a closer look at the sources of fresh water and find out which part of the planet has the most of it:

• Snow and ice at the North Pole make up 1/10 of the total fresh water reserve.
• Today, groundwater also serves as one of the main sources of water production.
• Freshwater lakes and rivers are typically located at high elevations. This water basin contains the main reserves of fresh water on Earth. Canadian lakes contain 50% of the world's total freshwater lakes.
• River systems cover about 45% of our planet's land area. Their number is 263 units of water basin suitable for drinking.

From the above, it becomes obvious that the distribution of fresh water reserves is uneven. Somewhere there is more of it, and somewhere it is negligible. There is one more corner of the planet (besides Canada) where the largest reserves of fresh water on Earth are. These are countries Latin America, 1/3 of the world's total volume is located here.

The largest freshwater lake is Baikal. It is located in our country and is protected by the state, listed in the Red Book.

Shortage of usable water

If we go from the opposite direction, then the continent that most needs life-giving moisture is Africa. There are many countries concentrated here, and they all have the same problem with water resources. In some areas there is extremely little of it, and in others it simply does not exist. Where the rivers flow, the water quality leaves much to be desired, it is at a very low level.

For these reasons, over half a million people do not receive water of the required quality, and, as a result, suffer from many infectious diseases. According to statistics, 80% of disease cases are associated with the quality of fluid consumed.

Sources of water pollution

Water conservation measures are a strategically important component of our lives. Fresh water is not an inexhaustible resource. And, moreover, its value is small relative to the total volume of all waters. Let's look at the sources of pollution so we know how we can reduce or minimize these factors:

• Wastewater. Numerous rivers and lakes were destroyed by wastewater from various industrial production, from houses and apartments (household slag), from agricultural complexes and much more.
• Disposal of household waste and equipment in the seas and oceans. Very often practiced similar look disposal of rockets and other space devices that have served their useful life. It is worth considering that living organisms live in reservoirs, and this greatly affects their health and water quality.
• Industry ranks first among the causes of water pollution and the entire ecosystem as a whole.
• Radioactive substances, spreading through water bodies, infect flora and fauna, making the water unsuitable for drinking, as well as for the life of organisms.
• Leakage of oil-containing products. Over time, metal containers in which oil is stored or transported are subject to corrosion, and water pollution is a result of this. Atmospheric precipitation containing acids can affect the condition of the reservoir.

There are many more sources, the most common of them are described here. In order for the fresh water reserves on Earth to remain suitable for consumption for as long as possible, they need to be taken care of now.

Water reserve in the bowels of the planet

We have already found out that the largest reserve of drinking water is in glaciers, snow and soil of our planet. In the depths of fresh water reserves on Earth are 1.3 billion cubic kilometers. But, in addition to the difficulties in obtaining it, we are faced with problems associated with its chemical properties. The water is not always fresh; sometimes its salinity reaches 250 grams per 1 liter. Most often there are waters with a predominance of chlorine and sodium in their composition, less often - with sodium and calcium or sodium and magnesium. Fresh groundwater is located closer to the surface, and salt water is most often found at a depth of up to 2 kilometers.

How do we spend this most valuable resource?

Almost 70% of our water is wasted to support the agricultural industry. In each region this value fluctuates in different ranges. We spend about 22% on all global production. And only 8% of the remainder goes to household consumption.

More than 80 countries are facing a decline in drinking water reserves. It has a significant impact not only on social but also economic well-being. It is necessary to look for a solution to this issue now. Thus, reduced consumption of drinking water is not a solution, but only aggravates the problem. Every year, the supply of fresh water decreases to 0.3%, and not all sources of fresh water are available to us.

The main source of fresh water is precipitation, but two other sources can also be used for consumer needs: groundwater and surface water.

Underground springs. Approximately 37.5 million km3, or 98% of all fresh water in liquid form, is groundwater, with approx. 50% of them lie at depths of no more than 800 m. However, the volume of available groundwater is determined by the properties of the aquifers and the power of the pumps pumping out the water.

Groundwater reserves in the Sahara are estimated at approximately 625 thousand km3. Under modern conditions, they are not replenished by surface fresh waters, but are depleted when pumped out. Some of the deepest groundwater is never included in the general water cycle, and only in areas of active volcanism does such water erupt in the form of steam.
However, a significant mass of groundwater still penetrates the earth's surface: under the influence of gravity, these waters, moving along waterproof, inclined rock layers, emerge at the foot of the slopes in the form of springs and streams.
In addition, they are pumped out by pumps, and also extracted by plant roots and then enter the atmosphere through the process of transpiration.

The water table represents the upper limit of available groundwater. If there are slopes, the groundwater table intersects with the earth's surface, and a source is formed. If groundwater is under high hydrostatic pressure, then artesian springs are formed at the places where they reach the surface.
With the advent of powerful pumps and the development of modern drilling technology, the extraction of groundwater has become easier.
Pumps are used to supply water to shallow wells installed on aquifers. However, in wells drilled to greater depths, to the level of pressure artesian waters, the latter rise and saturate the overlying groundwater, and sometimes come to the surface.
Groundwater moves slowly, at a speed of several meters per day or even per year.
They are usually found in porous pebbly or sandy horizons or relatively impervious shale formations, and only rarely are they concentrated in underground cavities or underground streams.
For the right choice Well drilling sites usually require information about the geological structure of the area.

In some parts of the world, increasing consumption of groundwater is having serious consequences. Pumping a large volume of groundwater, incomparably exceeding its natural replenishment, leads to a lack of moisture, and lowering the level of this water requires greater costs for expensive electricity used to extract it.
In places where the aquifer is depleted earth's surface begins to subside, and natural restoration of water resources there becomes more difficult.

In coastal areas, excessive groundwater withdrawal leads to the replacement of fresh water in the aquifer with seawater and saline water, thereby degrading local freshwater sources.

The gradual deterioration of groundwater quality as a result of salt accumulation can have even more dangerous consequences. Sources of salts can be both natural (for example, the dissolution and removal of minerals from soils) and anthropogenic (fertilization or excessive watering with water with a high salt content).
Rivers fed by mountain glaciers usually contain less than 1 g/l of dissolved salts, but the mineralization of water in other rivers reaches 9 g/l due to the fact that they drain areas composed of salt-bearing rocks over a long distance.

Indiscriminate release or disposal of toxic chemicals causes them to leak into aquifers that provide drinking or irrigation water.
In some cases, just a few years or decades are enough for harmful chemicals got into groundwater and accumulated there in noticeable quantities. However, if aquifer once contaminated, it will take from 200 to 10,000 years to naturally cleanse itself.

Surface sources. Only 0.01% of the total volume of fresh water in liquid state is concentrated in rivers and streams and 1.47% in lakes. To store water and constantly provide it to consumers, as well as to prevent unwanted floods and generate electricity, dams have been built on many rivers.
The Amazon in South America, the Congo (Zaire) in Africa, the Ganges with the Brahmaputra in Africa have the highest average water consumption, and therefore the greatest energy potential. south asia, Yangtze in China, Yenisei in Russia and Mississippi with Missouri in the USA.

Natural freshwater lakes holding approx. 125 thousand km3 of water, along with rivers and artificial reservoirs, are an important source of drinking water for people and animals.
They are also used for irrigation of agricultural lands, navigation, recreation, fishing and, unfortunately, for the discharge of domestic and industrial wastewater. Sometimes, due to gradual filling with sediment or salinization, lakes dry up, but in the process of evolution of the hydrosphere, new lakes form in some places.

The water level of even “healthy” lakes can decrease throughout the year as a result of water runoff through the rivers and streams flowing from them, due to water seeping into the ground and its evaporation.
Restoration of their levels usually occurs due to precipitation and the influx of fresh water from rivers and streams flowing into them, as well as from springs. However, as a result of evaporation, salts coming with river runoff accumulate.
Therefore, after thousands of years, some lakes can become very salty and unsuitable for many living organisms.

Of the 1018 tons of water on Earth, only 3% is fresh water, of which 80% is unusable because it is ice that forms the polar caps. Fresh water becomes available to humans as a result of participation in the hydrological cycle, or the water cycle in nature, which is schematically depicted in Fig. 12.3. Every year, approximately 500,000 km3 of water is involved in the water cycle as a result of its evaporation and precipitation in the form of rain or snow. Theoretically, the maximum amount of fresh water available for use is approximately 40,000 km3 per year. It's about about the water that flows from the surface of the earth into the seas and oceans (the so-called runoff).

The water cycle in nature has been known since Old Testament biblical times:

“All the rivers flow into the sea, but the sea does not overflow,

To the place where the rivers flow -

They keep running there."

Book of Ecclesiastes, 1:7.

Rice. 12.3. The water cycle in nature.

The use of fresh water is usually divided into repeated use and irreversible consumption. In accordance with this, fresh water is also sometimes divided into reusable and irretrievably consumed.

Reuse of water can be illustrated through examples such as navigation, fish farming and hydroelectricity.

Irretrievably consumed fresh water becomes no longer available for reuse. This includes fresh water, which, after consumption, was lost as a result of evaporation (including by plant leaves); water included in the products, as well as runoff water that reached the sea (ocean) and mixed with salt water. The irreversible consumption of fresh water worldwide ranges from 2500 to 3000 km3 per year, of which approximately 10% is used for domestic purposes, 8% in industry, and the vast majority - 82% goes for irrigation in agriculture.

Water consumption

Water consumption for domestic purposes. For domestic purposes, water is used for drinking, cooking, washing, washing, flushing sewage into sewers and watering gardens and streets.

In Europe, the average domestic water consumption per capita is approximately 230 liters per day. This is approximately the same as during the Roman Empire. Approximately 10% of all water consumed by humanity is consumed for domestic purposes.

Water consumption for industrial purposes. Over 85% of water used for industrial purposes is consumed in cooling processes. The rest is consumed in washing processes, gas scrubbing, for hydraulic transport and as a solvent. Approximately half a million liters of water are used to produce each passenger car; this amount includes both wasted water and reused water.

Approximately 8% of all water used in the world is consumed for industrial purposes.

Water consumption and agriculture. Agriculture accounts for 82% of the world's water use. This water is used for irrigation. Growing one ton of cotton requires 11,000 million liters of water. Growing a ripe pumpkin requires 150 liters of water.

Water consumption to generate hydropower. Over 50% of the UK's total water supply is used in power stations. Water is used in hydroelectric power plants, as well as in thermal power plants - to create steam that rotates turbines and for cooling purposes. Although power plants consume huge amounts of water, it is used with virtually no losses, in a closed cycle.

It is estimated that by the twenty-first century, water consumption throughout the world is expected to exceed natural supply. To solve this problem, they are developing various ways obtaining fresh water, which are described below.

Increased freshwater inflow. Most of the water flowing from the surface of the earth into the oceans is wasted, useless for human needs. Building reservoirs and drilling wells to extract groundwater increases the amount of water used by humans before it ends up in the oceans.

During hot weather, large quantities of water are lost from lakes and reservoirs through evaporation. This can be prevented by covering the surface of the water with a thin film of 1-hexadecanol alcohol.

Use of sea water and brackish waters. Fresh water can be obtained from sea water by desalting as a result of vacuum distillation in evaporators.

The distillation of water in them is carried out under reduced pressure. However, this method requires a lot of energy and is only economical in countries such as Kuwait, where energy is relatively inexpensive. low prices, and there is very little rainwater.

Fresh water can also be obtained using electrodialysis (see Section 10.3) from brackish water. Such water is found in river mouths; it has a salinity intermediate between fresh river water and salt sea water.

There are currently over 2,000 desalination plants operating worldwide. To desalt water, not only vacuum distillation and electrodialysis methods are used, but also freezing methods, ion exchange and reverse osmosis.

drinking water hygienic quality

Fresh water resources exist thanks to the eternal water cycle. As a result of evaporation, a gigantic volume of water is formed, reaching 525 thousand km3 per year.

86% of this amount comes from the salty waters of the World Ocean and inland seas - the Caspian. Aralsky and others; the rest evaporates on land, half due to transpiration of moisture by plants. Every year, a layer of water approximately 1250 mm thick evaporates. Some of it falls again with precipitation into the ocean, and some is carried by winds to land and here feeds rivers and lakes, glaciers and groundwater. A natural distiller is powered by the energy of the Sun and takes approximately 20% of this energy.

Only 2% of the hydrosphere is fresh water, but it is constantly renewed. The rate of renewal determines the resources available to humanity. Most of the fresh water - 85% - is concentrated in the ice of the polar zones and glaciers. The rate of water exchange here is less than in the ocean and amounts to 8000 years. Surface waters on land renew themselves approximately 500 times faster than in the ocean. River waters are renewed even faster, in about 10-12 days. Greatest practical significance rivers have fresh waters for humanity.

Rivers have always been a source of fresh water. But in modern era they began to transport waste. Waste in the catchment area flows along river beds into the seas and oceans. Most of the used river water is returned to rivers and reservoirs in the form of wastewater. Until now, the growth of wastewater treatment plants has lagged behind the growth of water consumption. And at first glance, this is the root of evil. In reality, everything is much more serious. Even with the most advanced purification, including biological, all dissolved inorganic substances and up to 10% of organic pollutants remain in treated wastewater. Such water can again become suitable for consumption only after repeated dilution with pure natural water. And here the ratio of the absolute amount of wastewater, even purified, and the water flow of rivers is important for people.

The global water balance showed that 2,200 km of water per year is spent on all types of water use. Effluent dilution consumes almost 20% of the world's freshwater resources. Calculations for 2000, assuming that water consumption standards will decrease and treatment will cover all wastewater, showed that 30 - 35 thousand km3 of fresh water will still be required annually to dilute wastewater. This means that the world's total river flow resources will be close to exhaustion, and in many areas of the world they are already exhausted. The amount of fresh water does not decrease, but its quality drops sharply and it becomes unsuitable for consumption.

Humanity will have to change its water use strategy. Necessity forces us to isolate the anthropogenic water cycle from the natural one. In practice, this means a transition to a closed water supply, to low-water or low-waste, and then to “dry” or non-waste technology, accompanied by a sharp reduction in the volume of water consumption and treated wastewater.

Fresh water reserves are potentially large. However, in any area of ​​the world they can be depleted due to unsustainable water use or pollution. The number of such places is growing, covering entire geographic areas. Water needs are unmet for 20% of the world's urban and 75% of the rural population. The volume of water consumed depends on the region and standard of living and ranges from 3 to 700 liters per day per person. Industrial water consumption also depends on economic development of this area. For example, in Canada, industry consumes 84% ​​of all water withdrawals, and in India - 1%. The most water-intensive industries are steel, chemicals, petrochemicals, pulp and paper, and food processing. They consume almost 70% of all water spent in industry. On average, industry uses approximately 20% of all water consumed worldwide. The main consumer of fresh water is agriculture: 70-80% of all fresh water is used for its needs. Irrigated agriculture occupies only 15-17% of agricultural land, but produces half of all production. Almost 70% of the world's cotton crops depend on irrigation.

The total flow of rivers in the CIS (USSR) per year is 4,720 km3. But water resources are distributed extremely unevenly. In the most populated regions, where up to 80% of industrial production resides and 90% of land suitable for agriculture is located, the share of water resources is only 20%. Many areas of the country are insufficiently supplied with water. This is the south and southeast of the European part of the CIS, the Caspian lowland, south Western Siberia and Kazakhstan, and some other areas Central Asia, south of Transbaikalia, Central Yakutia. The northern regions of the CIS, the Baltic states, the mountainous regions of the Caucasus, Central Asia, Sayan and Far East.

River flows vary depending on climate fluctuations. Human intervention in natural processes has already affected river flow. In agriculture, most of the water is not returned to rivers, but is spent on evaporation and the formation of plant mass, since during photosynthesis hydrogen from water molecules is converted into organic compounds. To regulate river flow, which is not uniform throughout the year, 1,500 reservoirs were built (they regulate up to 9% of the total flow). On the flow of rivers of the Far East, Siberia and the North of the European part of the country economic activity So far it has had almost no effect on humans. However, in the most populated areas it decreased by 8%, and in rivers such as Terek, Don, Dniester and Ural - by 11 - 20%. Water flow in the Volga, Syr Darya and Amu Darya has noticeably decreased. As a result, the flow of water to Sea of ​​Azov- by 23%, to Aral - by 33%. The level of the Aral Sea dropped by 12.5 m.

When obtaining drinking water, two main groups are distinguished according to its origin: groundwater and surface water. The group of groundwaters is divided into:

• 1. Artesian waters. We are talking about waters that rise to the surface from underground space with the help of pumps. They can lie underground in several layers or so-called tiers, which are completely protected from each other. Porous soils (especially sands) have a filtering and, therefore, purifying effect, unlike fractured rocks. With appropriate long-term residence of water in porous soils, artesian water reaches average soil temperatures (8-12 degrees) and is free from microbes. Due to these properties (almost constant temperature, good taste, sterility), artesian water is particularly preferable for drinking water supply purposes. Chemical composition water usually remains constant.
• 2. Infiltration water. This water is extracted by pumps from wells whose depth corresponds to the bottom of a stream, river or lake. The quality of such water is largely determined by the surface water in the watercourse itself, i.e. water obtained using infiltration water intake is more suitable for drinking purposes than cleaner water in a stream, river or lake. In this case, there may be fluctuations in its temperature, composition and odor.
• 3. Spring water. We are talking about underground water that flows naturally onto the surface of the earth. Being underground water, it is biologically impeccable and its quality is equal to artesian water. At the same time, spring water experiences strong fluctuations in its composition not only during short periods of time (rain, drought), but also over the seasons (for example, snow melting).

Surface waters, in turn, are divided as follows:

• 1. River water. River water is the most susceptible to pollution, and therefore is the least suitable for drinking water supply. It is polluted by waste products of people and animals. In yet to a greater extent River waters are polluted by incoming wastewater from workshops and industrial enterprises. The self-cleaning ability of the river can only partially cope with these pollutants. The preparation of river water for drinking water supply purposes is also difficult due to strong fluctuations in the pollution of river water, both in quantity and in composition.
• 2. Lake water. This water, even extracted from great depths, is extremely rarely impeccable in biological terms and therefore must undergo special purification to drinkable conditions.
• 3. Water from reservoirs. We are talking about water from small rivers and streams that are dammed in the upper reaches, where the water is least polluted. Water from reservoirs is categorized in the same way as Lake water. In all cases, when choosing the method and volume of necessary water treatment measures, the decisive factor is how heavily this water is polluted and how high the self-purifying ability of this “drinking water storage” is.
• 4. Sea water. Sea water cannot be supplied to the drinking water supply network without desalting. It is extracted and undergoes water treatment only from sea ​​coast and on islands, if it is not possible to use another source of water supply.