How to Deep Clean a Bathtub and Remove Soap Scum

Soap scum is the film that builds up on your tub from the interaction between soap residue and minerals in your water—and it gets worse the harder your water is. Left alone, it traps moisture and turns gray or brown, making your bathroom look dingy even when it's clean. A deep clean strips that buildup away, restores the shine, and actually makes routine cleaning easier going forward because you're starting fresh. The job takes an afternoon and requires nothing more than household items you probably already own.

  1. Prime the Surface with Heat. Remove any items from the tub, then rinse it thoroughly with hot water to soften the soap scum and loosen surface dirt. Wipe away any loose debris with a damp cloth. This prep work lets your cleaners actually make contact with the buildup instead of sliding over loose grit.
  2. Blend Your Secret Weapon. Pour half a cup of baking soda into a small bowl and add white vinegar slowly, stirring as you go, until you reach a thick paste consistency that won't run off vertical surfaces. If you're tackling a large tub, double the batch. The mixture will fizz—that's the chemical reaction that breaks down soap scum.
  3. Coat Every Scum Surface. Using an old toothbrush, paint stick, or putty knife, spread the paste directly onto every visible area of soap scum. Work systematically from the rim down, covering the walls, the tub floor, and the overflow hole. Don't worry about being neat—you're going to scrub this off anyway. Pay special attention to the corners and the waterline where scum accumulates fastest.
  4. Chemistry Does the Work. Leave the paste undisturbed for 15 minutes. The baking soda acts as a gentle abrasive while the vinegar's acidity eats at the mineral and soap deposits. Don't skip this waiting period—it's doing the heavy lifting so your scrubbing doesn't have to.
  5. Break Down the Buildup. Using a stiff-bristled grout brush or an old deck brush, scrub the paste in circular motions across all surfaces. Apply firm pressure—this is where the physical work happens. You'll see the scum break up and roll into little gray balls. Keep scrubbing until the tub surface feels smooth to the touch and you see white porcelain or fiberglass again.
  6. Flush Out All Residue. Fill the tub with hot water and let it drain completely, flushing away all the paste, scum debris, and residue. Repeat this rinse cycle two more times to make sure no baking soda or vinegar remains, which can leave a film. Use the shower head if you have one to spray down walls and corners.
  7. Deploy Heavy Artillery. For scum that didn't come off with the paste and brush, wet a pumice stone and scrub directly on the tub surface using light to medium pressure. The stone gradually wears away mineral deposits without scratching acrylic or fiberglass. Work in small circular motions and rinse frequently to see your progress. This works especially well on tub floors where you can apply heavier pressure.
  8. Call In Reinforcements. If the paste method didn't fully remove stubborn soap scum, switch to a commercial bathroom cleaner formulated for soap scum and hard water stains. Apply it according to the product instructions, usually spraying and letting it sit for 5–10 minutes, then scrubbing and rinsing. These products contain stronger acids than vinegar and work faster on months-old buildup. Choose one labeled safe for your tub material (acrylic, fiberglass, or porcelain).
  9. Verify Your Victory. Wipe down the entire tub with a dry cloth or old towel to prevent water spots and to see clearly what you've accomplished. Check the walls, floor, and rim in bright light. If you spot remaining scum in a particular area, apply the baking soda paste again to just that spot, wait 10 minutes, and scrub.
  10. Prevent Tomorrow's Buildup. To prevent heavy soap scum from building up again, spray your tub with a 1:1 vinegar and water solution after each bath or shower, and squeegee or wipe it dry. This takes 30 seconds and stops buildup before it starts. Once a month, do a quick scrub with the baking soda paste as a refresh. Hard water areas should do this more often—every two weeks if you shower daily.