● After using the correct amount of bleach-based product on various surfaces, you should leave the room for 20 or 30 minutes, Cummings says. “A lot of times, when people have mildew or mold, they spray it and then immediately start scrubbing. But that doesn’t give the product enough time to actually work,” she says. “So spray everything down really intensively, let it sit, and when you come back, you’ll notice that half the work’s already done for you.” When you return, consider scrubbing your shower with a toothbrush. “It’s really your best friend to get those problem areas,” Cummings says.