Disadvantages of using hard water are:
1. Hard water is unfit for washing as it is difficult to form lather with soap.
2. Scum may form in a reaction with soap, wasting the soap.
3. Furring of tea kettles will take place due to the formation of carbonates of calcium and magnesium.
4. Hard blocks hot water pipes. This is due to the formation of layers of carbonates of calcium and magnesium.
