Generally speaking, water with hardness of 0-60 mg/L is soft water, 60- 120 mg/L is medium hard water, 120- 180 mg/L is hard water, and 180 mg/L or above is extremely hard water. Therefore, water with a hardness value exceeding 120 mg/L can be considered as high hardness water.
Low hardness of water quality means that the concentration of calcium ions and magnesium ions in water is relatively low, and the hardness value is usually between 0 and 60 mg/L. This kind of water is usually soft and easy to use and treat, but in some specific cases, too low hardness value may also have some negative effects on water quality, such as corrosiveness and stability to water. Therefore, the hardness value of water needs to be evaluated according to the actual situation, and appropriate treatment methods and measures should be selected to ensure the safety and stability of water quality.