Charlie's soap laundry booster and hard water treatment. Excellent solution if you have hard water, well water, or that extra tuff stain that just doesn't want to go away. One half Tablespoon added to your washload along with our regular product provides supercharged cleaning power. Charlie's Soap Laundry Booster rinses cleans leaving no residue. This booster is designed to be used only as needed, and contains a biodegradable phosphate that does not harm the environment if used as instructed.NOTE: First time users may find that it requires a few washings with Charlie's Soap and Booster before old, previously deposited, irritating laundry detergents are completely removed. If you notice anything other than clean, soft clothes, rewash. The more you wash with Charlie's Soap and Booster, the cleaner your clothes will get.