Reliable information about the quality of drinking water interests everyone. A lot of sites on the network are dedicated to this, but among them the resources of interested parties prevail: manufacturers of bottled water and filters for purification. Therefore, it is better to understand the “water” issue using independent information resources and your own logic.
It is all about salts, or rather, their quantity. If there are a lot of them, the water is hard, not enough - the water is soft. Distilled water does not contain salts at all, and right away we say that it is definitely not suitable as drinking water.
The term “hard” did not happen by chance: the fabric after washing with soap in water with a high salt content was actually hard to the touch.
Hard water
Hardness - these are properties due to the content of calcium, magnesium and some other elements in the water.
Rigidity is of two types:
- Temporary is determined by calcium and magnesium bicarbonates.
- The constant is due to the same calcium and magnesium, but in the form of other salts - sulfates and chlorides.
You and I are interested in the first option, because it is it that is carbonate hardness. She has a wavy seasonal character. The fact is that bicarbonates are “mixed” into natural water during its flow through rocks such as limestone, gypsum or dolomites. If the water is surface, the highest percentage of “mixing” occurs in winter: winter water is relatively harsher. Least of all bicarbonates in spring water, especially during floods and floods: there is a serious diluting addition of melt and rainwater.
Underground natural waters, in contrast to surface waters, are more rigid and constant in composition: they do not depend on the seasons.
Units of carbonate hardness of water in Russia and abroad
In terms of measurement, there is an amazing international confusion. Surprising because the methods and units of measurement of other processes or objects are given under a single international measuring system a long time ago. Numerous metrological international and national organizations are involved in this business. Why carbonate hardness and other properties of water are still measured in each country in their own way, one can only guess. Judge for yourself:
In Russia, this is a degree of rigidity - 1 ° F. According to the standard GOST 31865-2012 "Water. Unit of rigidity "one Russian degree of rigidity is equal to the concentration of alkaline earth metal equal to ½ of its mmol / l. 1 ° W - 1 mEq / L.
Now, the units in countries are compared by the number of bicarbonates in a cubic decimeter of water:
- Russia: 1 ° W = 20 mg Ca² or 12 mg Mg²;
- Germany: 1 ° DH = 1 mg CaO;
- United Kingdom: 1 ° Clark = 10 mg CaCO³ in 0.7 dm³ of water;
- France: 1 ° F = 10 mg CaCO³;
- USA: 1 ° ppm = 1 mg CaCO3.
This international chaos can be dealt with. Many sites dedicated to water have built-in special tables and calculators for converting data from one system of units of measurement to another. To understand, for example, what carbonate hardness is acceptable for exotic goldfish with all the data in the French certificate.
Water salt standards
- First recommendations of the World Health Organization:
On water hardness, including carbonate hardness, WHO does not give any recommendations. Limits are indicated only for the content of two alkaline earth metals: calcium in the range of 20–80 mg / l, and magnesium in the range of 10–30 mg / l.
- Russian water standards are more specific and tougher:
Water hardness should not exceed 7 ° F, magnesium content should not exceed 50 mg / l, and no limits are indicated for calcium.
- Now, the Russian norm SanPiN 2.1.4.1116-02, which determines what carbonated hardness of water should bottled water have in terms of their physiological value:
Calcium is allowed in a very wide range of 20-130 mg / l; magnesium is determined with limits of 5.0 - 65.0 mg / l; water hardness is allowed within 1.5 - 7.0 ° W. Please note that no indicator has a lower limit with a zero level. This means that in any brand of drinking water there must be general and carbonate hardness. More about this below.
Types and properties of hard water
Natural waters are generally characterized by general hardness, so they are divided into groups according to this criterion:
- very soft water with a salt content not higher than 1.5 mEq / l;
- soft water with a salt concentration in the range from 1.5 to 4 mEq / l;
- medium hard water with limits of 4–8 mEq / l;
- hard water is at a salt content of 8 to 12 mEq / l;
- very hard water is recognized if it contains more than 12 mEq / l.
Now attention, a few words about one very simple chemical reaction. If water is boiled with hydrocarbonate salts dissolved in it, these salts will lose their “hydro” prefix and turn into ordinary carbonate salts. And carbonate salts were never soluble, they form in the form of a precipitate - the same scale that we do not like so much at the bottom of the teapot.
About the scum
In any natural water, well-soluble bicarbonates are necessarily present, which when boiled will give us scale. The most interesting thing is that any bottled drinking water of good quality will also give us scale when boiled. So for those who mistakenly believe that natural spring water should not precipitate when boiling, it is time to get rid of this stereotype.
No need to be afraid of scale; this is a completely natural chemical process for any high-quality water. Moreover, if the bottled water you bought does not give scale at all, you need to check it for calcium and magnesium: most likely, they are not there in the right amount. You didn’t buy distilled water, right?
Real hard water victims: pipes, risers and boilers
Magnesium and calcium salts precipitate not only upon boiling, but also under ordinary conditions. Remember the white coating on the taps and pipes in the bathroom. This is just what is visible to your eye. But water pipes of large caliber, boilers and risers can be coated on the inside with a serious layer of limescale. It will not lead to anything good: the pipes will overheat and fail due to fistulas and the formation of very unpleasant under-slurry corrosion.
On the other hand, too soft water in the water supply network will also bring trouble in the form of corrosion of metal pipes. So everything is good in moderation: a moderate level of salts in the water, combined with monitoring the condition of the inner walls of the main water pipelines.
Well, the best way to solve the "pipe" problem is to produce and use water pipes from new composite materials.
Water softening methods
- The simplest and most wonderful method is the elementary boiling of water, which was described above.
- The simplest chemical way is to add slaked lime.
If the first two methods related to carbonate hardness, it is more difficult to deal with constant hardness. But this is quite real:
- Freezing ice. It is not necessary to completely freeze the water and drain the remaining approximately 10%. Thaw the ice, it will be free of salts.
- Distillation with the evaporation of water, since salts are not volatile.
Now industrial disposal technologies:
- The action of magnetic fields.
- Industrial cationic purification with reagents and subsequent determination of carbonate hardness.
- The most effective way is osmosis with filters for ion exchange, as a result of which the “hard” salts are replaced by “soft” ones.
Hard water and health myths
The carbonate hardness of water negatively affects the skin: when washed, it dries the skin. Foam is poorly formed in such water when using soap or other detergents. These facts are repeatedly verified and it is worth taking them into account.
But with two other "horror stories" associated with the consumption of water with high carbonate hardness, it is necessary to understand. We are talking about skin lesions in the form of eczema and urolithiasis - two of the most popular diseases cited by manufacturers of bottled water and water filters for cleaning.
The wording in such sources is cautious: "there is evidence that high rigidity contributes to the formation of urinary stones ...". And if you look into the professional resources for clinical doctors, then there are quite clear. Most studies suggest that the hardness of the water consumed does not affect the risk of stone formation.
The same story with eczema and diathesis in children. In a word, read medical resources.
Water for the aquarium and its indicators
Both types of water hardness are important for aquarium inhabitants: both permanent and temporary carbonate.
Numerous tests to determine the quality of aquarium water are issued to determine the constant hardness - the level of Ca ++ and Mg ++ ions.
Standards of carbonate hardness in the aquarium are mandatory, as they play a crucial role in the life of fish.
Water hardness in the aquarium should be in the range of 3-15 ° W.
It is important to remember that the inhabitants of the aquarium actively consume calcium, so its concentration will constantly decrease. It is necessary to monitor and maintain the standard composition of the aquarium water also constantly.
In conclusion, I would like to wish readers a competent and balanced attitude to their health. This means informational independence and the ability to draw your own conclusions about how to behave and what water to drink.