Why Doesn’t Soap Lather in Hard Water?
It sometimes happens that soap does not produce lather in seemingly clear and clean water, and laundry doesn’t come out clean. One might think that the cleaning products are of poor quality, but often the problem lies in hard water.
What Causes Soap to Lather?
Soap is made up of sodium and potassium salts of fatty acids. When it comes into contact with water, these break down into sodium ions and anions of fatty acids, which provide the lathering properties of the soap. Through friction, impurities from surfaces (such as skin) are captured, resulting in the formation of foam.
How Does Hard Water Affect Soap?
Hard water contains high concentrations of calcium and magnesium salts. When these come into contact with various surfaces, they leave a white residue that can turn into stubborn lime scale when heated. This leads to quick clogging of pipes and damage to household appliances.
When attempting to dissolve soap in hard water, the anions of fatty acids form bonds with the cations of calcium and magnesium. These bonds are so strong and large that they can be seen as flocculent deposits on the surface of the water. As a result, the ions of fatty acids are removed from the solution, causing soap to stop lathering. The higher the hardness level in the water, the less effective cleaning products will be.
What to Do About Hard Water?
The issue of hard water often affects owners of natural water sources such as wells or cisterns. However, in some regions, lime scale formation also occurs with tap water. While such water is safe for drinking, the main problem—lime scale—remains. It is known that lime scale formation begins at a concentration of calcium and magnesium salts in water starting from 3 mg-equivalent/l.
To reduce excess hardness salts in water, ion exchange filters can be installed. Inside these filters is a special granulated resin. As water passes through this filtering layer, calcium and magnesium ions exchange places with neutral sodium ions. This process softens hard water. The regeneration of the filter material is done using a solution of regular table salt supplied from a special tank.
It’s important to understand that hardness salts are easily soluble substances in water; therefore, they cannot be removed by conventional mechanical filters with cartridges.