Usually, what we call "hard water" and "soft water" mainly refer to the contents of calcium carbonate and magnesium carbonate, which are expressed by "mg of calcium carbonate/liter of water" or "ppm" and are called the hardness of water.
Generally speaking, the hardness of water is divided into four grades:
1. Soft water: 0-60ppm
2. Slightly hard water: 60- 120ppm
3. Hard water: 120- 180ppm
4. Extremely hard water: 18 1ppm or more.
Extended data:
Hardness requirements of edible water
When the hardness of water is too high, it is not delicious to drink, and it is easy to produce white precipitated scale in water. If the scale is attached to the heating container or heater, it will prolong the heating time and waste energy. When the hardness of water is high, soap is not easy to foam and needs to waste more detergent. Scale can't be absorbed after entering the human body, and it is the enemy of health.
Known methods for treating drinking water include distillation, boiling, reverse osmosis, ion exchange, activated carbon filtration and ozone disinfection. Some of these methods can only be simply sterilized, some can remove bacteria, microorganisms and suspended solids, and some can remove chloroform, organic matter and odor. At present, only RO reverse osmosis water treatment technology can be called the most advanced and practical water treatment technology.
It is very important to find an ideal water purification method to improve the quality of life and promote health. We should have an understanding that the goal of purifying water quality is to soften hardness and remove pollutants that have an impact on health.
References:
Hard water-Baidu encyclopedia