Fresh Water Tank Sanitizer Kills More Than 99 Percent Of Bacteria In 60 Seconds. It Is A Non-Additive; Meant To Clean And Sanitize The Walls Of The Tank And Plumbing; Not The Water. Some RVers Use Chlorine Or Bleach Based Additives To Control Bacteria; Adding Them Directly To Their Fresh Water And Drinking It. However; Bleach Combines With Organic Matter To Form Known Carcinogens Called Trihalomethanes. And Bleach Is Very Corrosive; May Damage Seals And Leaves A Lingering; Unpleasant Taste And Smell. Fresh Water Tank Sanitizer Is Free Of Bleach And Chlorine; And Leaves No Smell Or Taste.