What is Hard and Soft Water?

What is Hard and Soft Water?

Have you boil water using your regular pot and then one day you realize that the bottom of your pot covered by a brown colored slag? Where did this slag come from when you usually use clean, colorless and scentless water? Or maybe you have experienced while bathing or washing, the soap you use is difficult to lather. 

Should you know that around 60% of water on earth derived from ground water, and that the water we use has gone through a cycle called the water cycle (hydrologic cycle). During the cycle the water is in contact with rocks and soils containing lime which dissolved minerals. Based on the mineral content, water can be divided into hard and soft water. Hard water usually contains Ca2+ (calcium ion) and Mg2+ (magnesium ion). Another cause of the water hardness is the presence of other metal ions such as Fe2+ (ferrous ion), Sr2+ (Strontium), and Mn2+ (Manganese). Calcium in the water has the possibility to bond with bicarbonate (HCO3-), sulfate (SO42-), chloride (Cl-) and nitrate (NO3-). Meanwhile magnesium in the water has the possibility to bond with bicarbonate (HCO3-), sulfate (SO42-) and chloride (Cl-). The following equation shows the reaction of water hardness origins.

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Another question may briefly appear in your mind, if this kind of water is a health hazard or not? Of course not, because magnesium and calcium are minerals needed by our body. Calcium ions are required in the growth of bones and teeth, so as to prevent osteoporosis. There also a research studies told that hard water can lower the risk of heart disease and mortality. Hard water is not dangerous because it contain ions that easily soluble in water. But at the high rate hard water can cause the water to become cloudy also bring some another problem.

The first problem is pipe or crane in your house will be more quickly blocked by the slag produced from mineral deposits contained in this hard water. It is also increasing the cost of heating water due to the slag emergence on the kettle or water heater. Problems in the hair and skin may also appear as it looking dull and dry. Hard water is also not good to wash, the Ca2+ and Mg2+ ions binds to carbohydrates on the residual acid soap and form deposits that are not foaming the soap as well as decreasing its ability to cleaning up.

To solve this problem, you need to know in advance what kind of hardness water in your home or neighborhood. Is that temporary hardness or permanent hardness, so you can determine the way out to overcome these problems.

Temporary hard water containing bicarbonate ions (HCO3-), or it may be containing calcium bicarbonate compounds (Ca(HCO3)2) and or magnesium bicarbonate (Mg(HCO3)2). Water containing ions or compounds can be removed by heating the water until the water is free from Ca2+ and Mg2+. By heating the compound, CaCO3 and MgCO3 will settle on the bottom of a kettle. The occur reaction is :

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While the permanent hard water contains anion other than bicarbonate ions, such as Cl-, NO3- and SO42- ions. Because that hardness cannot be simply removed by heating, then to free the water from hardness must be done by chemical substance that can precipitate the ions contained in hard water as in the Lime-Soda Ash (Lime-Soda Softening) with the addition of lime (CaO), soda ash (Na2CO3) or can also through the addition of caustic soda (NaOH). Apart from a few examples of the process of softening hard water, there are many other ways that can be done.

Here are some simple tips you can do at home to overcome the problems of hard water.

1. Boil water before use
2. Adding lime, washing soda, or lemon juice to the water in the bath shelter. But this way will take a long time.
3. Adding ammonia, borax, alkali or washing soda to the water used for washing.
4. Use white vinegar on tile, glass, and cranes to help remove mineral deposits.

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