Reliable information about the quality of drinking water is of interest to everyone. There are a lot of sites on the net devoted to this, but among them the resources of interested parties predominate: manufacturers of bottled water and filters for purification. Therefore, it is better to understand the “water” issue with the help of independent information resources and your own logic.
It's all about the s alts, or rather, their quantity. If there are a lot of them, the water is hard, if there are few, the water is soft. Distilled water does not contain s alts at all, and we must say right away that it is definitely not suitable for drinking.
The term "tough" is no coincidence: the fabric, after washing with soap and water with a high s alt content, actually felt stiff to the touch.
Hard water
Hardness is the properties due to the content of calcium, magnesium and some other elements in water.
There are two types of hardness:
- Time is determined by calcium and magnesium bicarbonates.
- The constant is due to the same calcium and magnesium, but in the form of other s alts - sulfates and chlorides.
We are interested in the first option, because it is he who is the carbonate hardness. It has an undulating seasonal character. The fact is that bicarbonates are "mixed" into natural water during its flow through rocks such as limestone, gypsum or dolomite. If the water is surface, the highest percentage of "mixing" occurs in winter: winter water is relatively hard. The least hydrocarbons are in spring water, especially during floods and floods: there is a serious diluting addition of melt and rainwater.
Underground natural waters, unlike surface ones, are more rigid and permanent in their composition: they do not depend on the seasons.
Units of measurement of carbonate hardness of water in Russia and abroad
There is a surprising international confusion in units of measurement. Surprising because the methods and units of measurement of other processes or objects were brought under common international measuring systems a long time ago. Numerous metrological international and national organizations are engaged in this business. Why carbonate hardness and other properties of water are still measured in each country in its own way, one can only guess. Judge for yourself:
In Russia, this is the degree of hardness - 1°F. According to the GOST 31865-2012 standard “Water. Unit of hardness”one Russian degree of hardness is equal to the concentration of an alkaline earth metal equal to ½ of itsmmol/l. 1°F – 1 mg-eq/L.
Now the units of measurement in countries in comparison by the amount of hydrocarbons in a cubic decimeter of water:
- Russia: 1°F=20 mg Ca² or 12 mg Mg²;
- Germany: 1°DH=1mg CaO;
- UK: 1°Clark=10 mg CaCO³ in 0.7 dm³ of water;
- France: 1°F=10mg CaCO³;
- US: 1°ppm=1 mg CaCo³.
This international chaos can be de alt with. Many sites dedicated to water have 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.
Standards for s alt content in water
WHO recommendations first:
On water hardness, including carbonate hardness, WHO does not give any recommendations. Limits are only for 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 regulations 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 standard SanPiN 2.1.4.1116-02, which determines what carbonate hardness of water bottled water should have in terms of their physiological value:
Calcium is allowed in very wide limits20–130 mg/l; magnesium is determined with limits of 5.0 - 65.0 mg/l; water hardness is allowed within the limits of 1.5 - 7.0°F. Note that none of the metrics has a lower bound of zero. This means that any brand of drinking water must contain total and carbonate hardness. More on that below.
Types and properties of hard water
Natural waters are mainly characterized by general hardness, so they are divided into groups according to this criterion:
- very soft water with a s alt content of no more than 1.5 meq/l;
- soft water with a s alt concentration ranging from 1.5 to 4 meq/l;
- water of medium hardness with limits of 4–8 mEq/l;
- hard water is when the s alt content is from 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 you boil water with bicarbonate s alts dissolved in it, these s alts will lose their "hydro" prefix and turn into ordinary carbonate s alts. And carbonate s alts have never been soluble, they form in the form of sediment - the very scale that we don't like so much at the bottom of the kettle.
About scale
In any natural water there are necessarily highly soluble hydrocarbons, which, when boiled, will give us scale. The most interesting thing is that any good quality bottled drinking water will also give us scale when boiled. So for those who mistakenly believe that natural spring water should not precipitate when boiled, it's timeget rid of this stereotype.
No need to be afraid of scale, this is a completely natural chemical process for any quality water. Moreover, if the bottled water you bought does not scale at all, you need to check it for the content of calcium and magnesium: most likely, they are not there in the right amount. You didn't buy distilled water, did you?
The real victims of hard water: pipes, risers and boilers
S alts of magnesium and calcium precipitate not only during boiling, but also under normal conditions. Remember the white coating on the faucets and pipes in the bathroom. It's just what your eye can see. But large-caliber water pipes, boilers and risers can be covered 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-sludge 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 s alts in the water, combined with monitoring the condition of the internal walls of the main water pipelines.
Well, the best way to solve the "pipe" problem is the production and use of 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 method is to add slaked lime.
If the first two methods were related to carbonate hardness, then it is more difficult to deal with constant hardness. But this is quite real:
- Freezing ice. It is necessary not to completely freeze the water and drain the remaining approximately 10%. Defrost ice, it will be free from s alts.
- Distillation with evaporation of water as s alts are non-volatile.
Now Industrial Disposal Technology:
- The action of magnetic fields.
- Industrial cation cleaning with reagents and subsequent determination of carbonate hardness.
- The most effective way is osmosis with ion exchange filters, as a result of which “hard” s alts are replaced by “soft” ones.
Hard water and he alth myths
Carbonate hardness of water has a negative effect on the skin: when washing, it dries the skin. In such water, foam does not form well when using soap or other detergents. These facts have been verified many times over and should be taken into account.
But two other "horror stories" associated with the consumption of water with high carbonate hardness need to be de alt with. 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 purification.
The wording in such sources is cautious: "there is evidence that high stiffness contributes to the formation of urinary stones …". And if you look into professional resources forclinicians, then there are quite clear. Most studies show that water hardness has no effect on stone risk.
Same story with eczema and diathesis in children. In short, read medical resources.
Water for the aquarium and its indicators
For the inhabitants of aquariums, both types of water hardness are important: both permanent and temporary carbonate.
Numerous aquarium water quality tests are available to determine permanent hardness - Ca++ and Mg++ ion levels.
The standards for carbonate hardness in an aquarium are mandatory, as they play a crucial role in the life of fish.
The hardness of the water in the aquarium should be between 3-15°F.
It is important to remember that the inhabitants of the aquarium actively consume calcium, so its concentration will constantly decrease. This needs to be monitored and the rate of composition of aquarium water also constantly maintained.
As a conclusion, I would like to wish readers a competent and balanced attitude to their he alth. This means informational independence and the ability to draw your own conclusions about how to behave and what water to drink.
