Hard water produces less lather with soap, so soap costs more.
If the water is too hard, then its taste becomes bad, so it is not used for drinking. Its use leads to kidney stone disease and dysentery.
The use of hard water causes a crust to settle on the surface of the boilers, which in turn increases the cost of fuel.
By reacting with salt water, acid is formed, which quickly destroys the surface of the boiler.