To solve this problem, you can boil the water beforehand. Hard water contains minerals that cause water spots and the lessened efficacy of soap so boiling hard water will break down and precipitate the minerals that are in it leaving the water softer. Make sure to wait for the water to become...
Why don't you boil the water beforehand? Boiling hard water will break down and precipitate the minerals that are in it leaving the water softer. Maybe it will be more effective.