What is water hardness definition. Water hardness level: how to determine water hardness at home

It is noteworthy that in most cases the hardness of the water on the surface of the earth is lower than in the case of groundwater. This is due to the fact that surface waters are involved in the famous water cycle in nature. During the cycle, water repeatedly changes its state of aggregation. Under the influence of high temperature, it evaporates, that is, turns into a gas. Then, in the gaseous state, it rises to the high layers of the atmosphere, where, at low temperatures, it turns into ice crystals and becomes a solid substance. Then in the form of precipitation falls to the surface, again becoming a liquid. As a result of these processes, the concentration of impurities, including hardness salts, varies, usually in the direction of decreasing. True, this does not apply to seawater - the salts from it evaporate, but their concentration is so great that it still remains very hard.

As is known, the hardness of water and its relation to a particular category depends on the concentration of salts of alkaline earth metals. The determination of the total hardness of the water is carried out by folding the temporary and constant hardness. Thus, when we speak of the total hardness of water, we mean the sum of the temporary hardness (that is, the concentration of bicarbonate salts, which can be distinguished during boiling) and constant hardness (the content of non-carbonate salts dissolved in water). It is believed that the best for constant consumption is water of medium hardness, that is, with indicators from 2.1 to 7 degrees of hardness. However, there is no single international standard in this matter: for example, in a number of Western countries it is recommended to use water, the hardness of which is up to 2 degrees of hardness, that is soft.

How to determine the hardness of water at home

In our age of high technology, the problem of how to measure the hardness of water is not worth it. Of course, there is a device for measuring the hardness of water - TDS-meter, or conductometer. A conductometer is not a specialized device for determining the hardness of water: its function is to measure the level of content in the liquid, not only salts, but also minerals, as well as measurements of electrical conductivity and other characteristics. After applying the TDS meter and getting on the display of certain values, the calculation of water hardness consists in applying special tables or formulas attached to each device to these indicators. In addition, a water hardness test can be carried out using special chemical rapid tests. Such an indicator of water hardness is most often used by aquarists who want to determine the parameters of water in aquariums on the subject of comfort for aquatic plants and fish.

But there are also household methods for determining the hardness of water that do not require special technical and chemical means. They are based on practical experience and accumulated over generations of external manifestations of increased water hardness. There are many inventive options for how to check the hardness of the water at home. The most common of these is an experiment with soap: in general, in hard water, soap foams worse than in soft water. The latter, in turn, washes away the soap from the hands, which remains in the form of a kind of soap film. However, in this case, you need to make a discount on the fact that various soap means may have special characteristics. The method of determining the hardness of water "by eye" includes monitoring the heating elements of household appliances and on hot water supply water pipes - if the water is hard, the scum forms much faster. If you want to conduct a "tasty" experiment, then be more attentive to the taste sensations - it is believed that soft water is tastier and more pleasant, while hard water gives off a metallic taste.

How to reduce water hardness

After one or other specialized or household methods determined the increased content of hardness salts, the problem arises of how to reduce the hardness of the water. The most reliable and safe, of course, scientific ways to eliminate water hardness. For example, water cationisation — the use of ion exchange resins, which, upon contact with hard water, react with cations of hardness salts and absorb them. Also widely known is the method of electrodialysis — the removal of hardness salts from water by the action of an electric current. The complete elimination of the hardness of water is carried out during distillation (distillation of water from one aggregative state to another), during which it turns out almost completely chemically pure, water devoid of impurities. Water is either first brought to a gaseous state, and then transferred from steam to a liquid; either from the gaseous state is transferred to the crystal structure.

Methods for eliminating water hardness also include reagent water softening by adding slaked lime or soda ash. It is based on the transfer of the hardness salts of calcium and magnesium into insoluble compounds and the formation of a precipitate that can be removed from the water. Reducing the hardness of the water is possible without the involvement of complex scientific technologies, conducting chemical experiments and unique devices. The easiest way to soften the water is boiling, which in the scientific lexicon has received the tricky name of the procedure of softening. In fact, the “thermal softening” is made by the majority of people who have scum every day in the kettle. This scum is a precipitate of hardness salts separated from water as a result of exposure to high temperature. However, boiling can only help in the case of variable stiffness - constant stiffness is not subject to such methods.

Alexander Babitsky

It is not accepted to argue that tap water is characterized by excessive rigidity. However, fans of a healthy way, as a rule, are more interested in the degree of “redundancy” of calcium and magnesium compounds harmful to the body, which can be determined with the help of ... ordinary laundry detergent!

Modern housewives are well aware that manufacturers of washing powder always indicate on the box the recommended conditions of use (including the allowable concentration of salts in the water). However, not everyone has the opportunity to conduct a comprehensive chemical analysis before each wash.

How to determine the hardness of water at home? And how the mysterious indicator “mmol per cubic meter” is deciphered. dm?

What is the average water hardness?

According to the scientific definition, water hardness is the total amount of salts dissolved in a liquid (mainly magnesium and calcium). This choice is due to the ability of bivalent metals to form stable chemical compounds - true satellites of the heating elements of washing machines, boilers and kettles.

Based on the definition, the mysterious abbreviation "3-7 mmol. per cubic meter dm. "can be decoded as follows: 200 ml. The detergent is sufficient for washing laundry in water containing the total amount of calcium and magnesium salts within the specified range.

Thus, the consumption of powder is directly proportional to the stiffness (Table 1).

Table 1. Powder consumption by 4-5 kg. linen

After identifying the main enemy of the washing machine, a logical question arises: "How do you know the hardness of the water?"

Condition of heating elements

The most striking evidence of the presence of magnesium and calcium salts in tap water is the rapidly forming scale on the surfaces of hot water pipes, as well as the heating elements of household appliances. If you actively deal with an uninvited guest often occur suspiciously, you can safely plan your family budget, taking into account the increased cost of cleaning powder.

Tea brewing time

It is believed that good tea in soft water is brewed in just 3-4 minutes. You should think about buying filters and cleaning systems if guests have to keep tea drinking longer than the specified time.

"Soap will foam, and the dirt will go somewhere ..."

It is known that in hard water soap solutions foam much worse, since calcium and magnesium ions “capture” soap into stable salt complexes. It is easy to identify soft tap water by a rich foam that does not wash well. However, this method does not differ in accuracy, since the degree of "blurring" largely depends on the components used by the manufacturer.

"Salt? - taste!"

Soft spring water is easily distinguished by its special, delicate taste. However, the “sharp” tap water is more familiar to most residents of megalopolises. According to studies, true gourmets can determine the quantitative content of magnesium and potassium salts with an accuracy of 2 mg-eq / l.

"My light, mirror, say ..."

Calcium is known to be the main “building block” of nails, hair and teeth. The lack of a vital mineral of the second group is often the main cause of dissatisfaction with its own reflection in the mirror. That is why very soft water, “flushing out” calcium from the body, is an extraordinary pass to the dentist’s office.

Long-term experience of survival in urban environments and the results of home "rapid tests" are today the main guide when choosing cleaning products for most housewives. However, it is unlikely that such approximate data can be safely used to determine the hardness of water or the choice of filtration filtration system.

Most probably, a burning problem that needs to be solved, if not immediately, then thought out for sure. If you have low quality water in your home, you have no choice. Such water must be softened, otherwise the consequences will be the most costly. It is a pity that we, as economical people, always wait and hope for it, and as a result we come to the idea of ​​reducing the hardness of water only when the washing machine fails, or in the boiler tube it breaks from overheating.

Hard water is made, as it is known, a high content of only two salts. These are calcium and magnesium salts. but hardness of water  by itself may be different, as well as the excess salt content may be different. Sometimes the rigidity can be carbonate, and it can also be sulphate. But since carbonate hardness is almost 98 percent of cases, we will consider the options for work using examples of this low-quality water. Dealing with the problems of poor water, consider in more detail the concepts themselves.

Table. Types of water hardness

So, according to the encyclopedia, the hardness of water is the calcium and magnesium cations dissolved in water. If water has a high harsh index, then when heated, these salts form a dense coating on the surfaces of the equipment. Do not shun this plaque formed in the human body. Only there it takes the form of sand or stones in the gallbladder, kidneys, and liver. Water hardness index largely determines its use both in enterprises and in everyday life. In any case, you should understand that the degree of water hardness causes the formation or non-formation of scale in household appliances or industrial equipment.

We often see stiffness designations like millimoles per liter. What does this mean? Millimole is a unit of volume of hardness salt per liter of substandard water. One millimol is the amount of substance in grams per liter, which is determined by the molecular weight of the substance, divided by its valence. If it is simpler to say, then one millimole per liter of calcium salt is 20.04 milligrams of this salt, while the millimole content of magnesium will be much lower and will amount to 12.1 milligrams. There is also such a designation for stiffness, as milligram per equivalent of liter and it can be safely equated to pray per meter cubic of water.

But a similar classification of units of measurement of rigidity is adopted more in the countries of the former Soviet Union, in the territories of other countries use another. In Germany, the degree of water hardness is determined in German degrees. In France it is a French degree, there is also an American degree. Therefore, always pay attention to the units of measurement. It may happen that which you will acquire for your apartment has been released abroad. All units of measurement are indicated there, they do not belong to the post-Soviet space, and it will be necessary to adjust their values ​​in order to understand what volume of water such devices are designed for.

In addition to the diversity of units of measurement, water hardness implies the inclusion of two components. The thing is that stiffness is formed by two subspecies. This is a temporary and permanent stiffness. We fight and deal with the temporary hardness of water, it is she who forms the scum.

Carbonate stiffness is often called temporary stiffness. These are inclusions in water in the form of impurities of calcium, magnesium, naturally, ferrous deposits can also be included here. By constant hardness in water is understood as nitrate, as well as sulfate and chloride anions. Their salts dissolve in water.

Since hardness has units of measure, and we know that hard water is a surplus of two salts in it, accordingly there should be a classification of degrees of hardness. How to determine that the water you have is of poor quality and should be softened?

Determination of water hardness: methods

If you suspect that your water is hard, that is, there are at least some primary signs, in the form of a bloom on the heating element of a kettle, a foul-water boiler or disgusting washing quality, then you need to conduct an estimated measurement of impurities in water. Such an examination of determining the hardness of water is inexpensive. Laboratories conducting a similar analysis, today there is probably in any more or less big city.

You may wonder why water assessment, if so clearly it is clear that the degree of rigidity is high? And, nevertheless, I think no one wants to overpay for the power of the device, which you do not need. That is why everywhere it is advised to carry out the determination of water hardness in order to know exactly what instruments are needed for in each particular case.

If you decide and did assess your water, then you should know the ranking of water types by degree of hardness. Water will be considered soft, in which the degree of hardness will be as high as 3 milligrams per liter equivalent, the average hardness is 3-6 milligrams, over 6 is already hard water and over 6 is very hard.

Where does the water come from all these impurities? After all, do not always use the nearby rivers and lakes in the city. Often, artesian wells are used, in which completely pure water flows, sometimes useful. After all, how many of us have a variety of pump-rooms, in which cranes are installed and we go there to drink just such useful water. many today. Some effective ways, some not.

But let's think about why water, which is considered useful, is allowed to drink only in certain doses? Each person, the doctor who deals with them, prescribes a certain diet and says how many grams of such water and according to what schedule you should drink. So the water is too high content of certain substances. Since it can not be drunk as much as you want. And what is an artesian well? Its presence underground does not mean that harmful impurities will not get into it. Under the ground has its own characteristics. Many methods for determining the stiffness, makes us think about the choice of a company offering a chemical analysis service.

How to determine the hardness of water with maximum accuracy?

Fortunately, a very effective way to determine the hardness of water with maximum accuracy was invented titrationThis is one of the most useful and common methods for determining the concentration of magnesium and calcium salts in water. The advantages of this method include its accuracy and high cost when ordering.

There are other devices besides titration that can determine the rigidity as accurately as possible, but they are either expensive or difficult to reach.

Where do you get all the minerals? Mainly from the ground, and from where the water can be pure, if it flows through the ground, which contains all these ores. Water is one of the best natural solvents, so long as it reaches the water intake system, it consumes all the impurities. This is limestone, dolomites, the results of weathering of rocks. The degree of water hardness is also influenced by the degree of water salinity. If it is about 80 percent, then the water becomes hard due to calcium ions mostly. Only sometimes and very rarely, the degree of magnesium hardness can be 50, or even 60 percent.

But when the degree of mineralization increases, the presence of calcium ions begins to decline sharply. In this case, the calcium content is rarely above one gram per liter. The amount of magnesium on the contrary increases. The greater the degree of mineralization of water, the more magnesium in it. This indicator is several units, if it is a salt lake, then the indicator of magnesium there has a mark in the region of ten.

With all this, although it seems that surface waters are much more polluted, nevertheless, the degree of their hardness is usually lower. The hardness of surface water is a habit to jump throughout the year. This happens because there is a period of melting snow, cold. When no one is bathing, the water is less polluted. The largest percentage of stiffness growth occurs at the end of winter, and the lowest percentage is during the flood period, that is, in early spring. During this period, it still often rains, and the stiffness is significantly diluted.

Sea or ocean water has the highest degree of water hardness from natural water types. Here, the indicator has long passed for 10 milligrams per equivalent of liter, sometimes this indicator exceeds even a hundred. And the content of calcium and magnesium in hard water of poor quality can be very different.

The most famous method of how to determine the stiffness is to make a chemical analysis of water. In Russia, many companies are engaged in this service and the cost of determining the hardness of water is not so expensive. With general hardness indicators, drinking water has its own requirements. Calcium in water will begin to taste, if the degree of its inclusion in water exceeds 2-6 milligrams per equivalent liter. For magnesium to be felt, it must be much less in water. Although for magnesium it happens that you can even use water with up to ten in your drink.

Now let's talk about the measurement of water hardness. What instruments are used to measure water hardness? At the same time, it is important to maintain the optimum content of hardness salts in water without fail. If they are removed completely, then such water will also be harmful to humans. And by the way, not only for him. Low carbonate salts cause cardiovascular problems.

As for the effect on the walls of the equipment, soft water also has a drawback. It causes corrosivity. Therefore, when heat treatment is carried out on surfaces after working with soft water, corrosion inhibitors are necessarily added to the water itself to inhibit its development.

As we can see, water has a certain degree of hardness by default. Water should not be too hard and too soft. Both options lead to negative consequences.

Due to the use of poor-quality water, not only materials, things and health are affected. There is also equipment and appliances that constantly work with water, there are also heating and water supply systems, where there is always water inside the equipment. In these industries, the use of the system is necessary, without fail.

Eliminate scum, after working with similar water of course you can. But this way, you spend a lot of time on work. The equipment will be idle, you will incur losses. Permanent purchases of funds to eliminate plaque. Once a year, global descaling with a complete disassembly of the equipment. No surface can withstand the treatment with aggressive agents for a long time. Therefore, with constant cleaning, the equipment will have to be changed earlier than when you use soft water.

Do not forget about the poor heat transfer of scale. Having received as a result of working with excess water hardness, a lime scale on the surfaces, your device starts to work poorly. Efficiency drops, the quality of water heating too. Only fuel costs increase. On which side do not look, but the removal is very expensive. Even if you compare it for the year of work with the most expensive - reverse osmosis.

Then the process of removing scale can never be allowed to drift. It is necessary to strictly control everything and prevent the development of scale to the limestone stage. In this case, the rupture of surfaces is possible, since no surface can heat itself for a long time. Heat will require a way out.

To deal with the hardness of water can and should be. Only elect for this should be high-quality devices softening poor-quality water. All filters presented on the markets today can be divided into two large groups. About what to choose, you decide for yourself, good water analysis, you have already conducted. If the results are not very old, and water is not drawn from primary sources, then this analysis will help you choose the right device for water purification.

For your own home or apartment today, it is increasingly recommended to use as simple as possible to install and operate. You will not suffer from constant unwinding by twisting. You do not have to change any parts or check the status of the backfill. In this device, everything is thought out for the convenience of users. First, it is based on an electric processor and powerful permanent magnets. The use of electricity has helped to multiply the magnetic force of exposure, and also made it possible to control the force of this impact. The frequency of electromagnetic waves generated by such a device can fluctuate and be adjusted accordingly up to 50 kHz. To do this, the device has a small control unit.

Methods for measuring water hardness:

• Chemical analysis of water;
• Complexometric method showing carbonate and temporary rigidity;
• Atomic spectrometry method.

Similar devices for measuring water hardness with any surfaces work. Whether it is metalplastic, cast iron or steel. The only important condition is that it will be necessary to eliminate old scale from the inside of the pipe. Through it, even powerful electromagnetic pulses are unable to break through.

Such a device is able to measure the hardness of water for 3-4 minutes, and you do not need to do anything special. You just buy and wind the device on the pipe, even plunge is not necessary. Electricity consumption is very gentle. That is, of the associated costs will only be the cost of electricity.

Choosing a device in your home, you need to remember, and understand that the use of a single cleaner does not guarantee you a full degree of protection against water hardness. You can not buy one filter jug ​​and then swim in this water. Such a device will not be able to clean this amount of water. You can not buy a magnetic device and hope that it guarantees quality drinking water. Magnetic installation does not purify water, it binds hardness salts, does not allow it to deposit on surfaces. However, it is a sin of all reagent-free softeners. Therefore, for the complex need to purchase a special device for softening drinking water.

Best of all with the measurement of water hardness copes device "ZEUS". Its main task is to filter out the excess content of hardness salts. This is characterized by high cleaning speed and ease of cartridge replacement. The device works with the help of an ion-exchange resin, which perfectly absorbs hardness salts from the water, instead of giving up useful sodium.

The size of such installations is not small, because in the filter itself you need somewhere to fall asleep funds for recovery. In everyday life, so that water does not come in contact with a harmful reducing agent, the cartridge is changed. In industry, cartridges are expensive and therefore they are reduced using salt over and above the purification.

And one more feature of the installation, characteristic for the industry. There can be two or three, and four softening devices in a row. The system works so that while one device is restored, the load falls on other devices. But you can restore the devices without disassembling and without stopping the installation each time.

The hardness of the water, as we see, is present in any water and it is imperative to “do something” with it. If you decide on such an acquisition, it is better to buy a device that will last a year. Only in the special requirements, when the requirements for the purification of water or for an extremely high degree of purification are made to water, then other types of hardness elimination are applied. As a rule, reverse-osmosis plants and ion-exchange filters are used most of all today. Before you panic, order a measurement of water hardness from professionals. In life, the most non-reagent types of softeners have found themselves.

The properties of any water depend on the concentration of calcium and magnesium salts in it. With the increased content of such substances in the pipes and on the walls of the dishes formed scum. Soap in hard water does not foam well, and after washing there is a feeling of dry skin. On the other hand, the low content of hardness salts, characteristic of soft water, causes corrosion of pipes.

How to determine the hardness of water at home?

1. White stains and roughness of fabrics after washing indicate an excess of salts of Mg and Ca in tap water. Flying on the tap and scum in the kettle are also signs of stiffness.
2. You can assess the quality of the water by the speed of brewing good tea.
3. It takes 3–4 minutes to prepare a drink from soft water, and 7–8 minutes from hard water.

More precisely, the concentration of salts helps the Trilon B reagent. The test strips sold in specialized departments and pet stores allow determining the level of water hardness.

What if the water is hard?

The easiest way to soften tap water is to boil it. To eliminate the salts, you can use soda ash. It is added at the rate of a teaspoonful of an agent for 5 liters of water. As a result of a chemical reaction, hardness salts precipitate.

Special preparations that change the properties of the liquid, released for dishwashers. Such emollients are produced, as a rule, in the form of tablets.

Remove salts that determine the hardness of water can be a variety of filters.

• Jug-type cleaners are the most popular due to their low cost and ease of operation. The main drawback of such a filter is its fragility: the system works for about 6 weeks, and then the cartridge needs to be replaced.
• Magnetic filter is a household appliance that neutralizes the ability of magnesium and calcium ions to salt formation. This happens due to the action of a constant magnetic field.
• Ion exchange filter. Tap water, getting into such a device, first enters the tank with resin, then passes through a salt solution.

The most thorough cleaning running water is subjected to a reverse osmosis system. However, together with the salts of magnesium and calcium, the filter also removes beneficial substances, so this water is not suitable for drinking.