toilet cleaners

Which Acid Is Present In Toilet Cleaner? Hydrochloric acid is used in toilet bowl cleaners to remove dirt and grime. Which acid is present in harpic? Harpic contains hydrochloric acid which dissolves limescale, calcium carbonate (CaCO3), as shown. Question 3 Hydrochloric acid is a solution of hydrogen chloride gas. What is toilet acid made of?