Scrubbing Bubbles has just the remedy for toilet rings and hard water stains in the toilet. Introducing Scrubbing Bubbles Drop-Ins. Just drop a tablet into your toilet tank to help keep your toilet bowl stain-free up to 4 weeks. With every flush your toilet enjoys glorious relief from stains caused by hard water minerals and limescale. That’s continuous odor protection for a continuous clean. The Scrubbing Bubbles way. Stain and smell protection for your toilet bowl that drops right in. That’s cleaning reinvented. Package includes 5 discs that lasts up to 4 weeks each.