Why is hard water not suitable for washing clothes with soap?

(N/A) Hard water contains dissolved salts of calcium and magnesium,specifically their bicarbonates,chlorides,and sulphates. When soap (which consists of sodium or potassium salts of long-chain fatty acids) is added to hard water,these calcium and magnesium ions react with the soap molecules to form insoluble precipitates known as scum. Because the soap molecules are consumed in this chemical reaction to form scum,they are no longer available to form micelles and perform the cleansing action on clothes.