The main use in the US is as ...
Published by Joseph Cotruvo, President at Joseph Cotruvo & Associates, Water , Environment and Public Health
The main use in the US is as a polish on filtered water or for unfiltered low turbidity water for crypto and giardia, because they are neutralized by low doses. Actually they are well removed by good filtration to 0.3 ntu. Chlorine is good for just about everything except crypto, and much less expensive.