Soaps are not suitable for washing clothes with hard water as they form insoluble precipitate on reacting with calcium and magnesium ions of hard water
Almost all over the world even for drinking hard water (includes Calcium & Magnesium) is available and soap has a great limitation that it produces scuum while washing anything in hard water.

Scuum is meant to be insoluble precipitates of Ca²⁺, Mg²⁺, Fe²⁺ etc. It is white in color.
1 5 1
Hope it may help you.. You can mark it best if you like my answer.. :)
waah.... bde intelligent ho gye ho... kya baat h..