Dissolves stains with bubbling action. Sani-Flush Toilet Bowl Cleaner with blue bubbling action is specially formulated to dissolve tough hard water and rust stains. Regular use of Sani-Flush Toilet Bowl Cleaner keeps white or colored bowls stain-free and sparkling clean. Does not harm septic tanks and plumbing. Use on toilet bowls only. Do not use on enameled or metal fixtures such as bathtubs and sinks. Contains no phosphates.