How strong is the hydrochloric acid in toilet bowl cleaners?

Hydrochloric acid used in toilet bowl cleaners comes in a variety of strengths ranging from a low of seven percent up to a maximum of 40 percent, depending upon the manufacturer. As of August, 2014, Vani-Sol Professional High Acid Bowl Cleanse has the highest content from 20 to 40 percent.

There are two types of toilet bowl maintenance products: general cleaners (which have a higher content of the acid) and calcium, lime and rust removers, which typically have a very low concentration of Hydrochloric acid. Hydrochloric acid is also known as Muriatic acid or Hydrogen chloride; any of these may be the main ingredient listed in the particular brand of toilet bowl cleaner chosen.