In the U.S. we use the term ...

Published by

In the U.S. we use the term residual chlorine, which includes all remaining after contact time, both free HOCl, OCl- and combined, monochloramine, if used.  Free + combined = Total. Please lets stick to one term and not use 'excess.' U.S. limits the residual to 4.0 mg/L and anything in excess of that would indeed be excessive.