Hard Water Makes Scale & Scum
Hard water doesn't easily form lather with soap, you get nasty scum instead. So you use more soap. Problem is the 'hardnesss minerals' in hadr water reacting with soap
It also forms furring/scale on inside of biolers, pipes and kettles. Badly scaled up pipes reduce efficiency of heating systems & may need to be replaced, which costs money & can eventually block pipes.
Scale = bit of a thermal insulator, so kettle with scale on heating element takes longer to boil, so is less efficient.
Plus, it can cause a horrible scum on…