Soap Scum Information, Prevention, and Removal

Everything You Did (and Didn’t) Want to Know About Soap Scum

Cleaning Soap Scum Off Shower Door
FotoDuets / Getty Images

It happens to everyone: A nearly spotless bathroom is marred by the appearance (and rapid growth) of a white or gray filmy layer on bathtub, shower, and sink surfaces. This layer is soap scum, a common development that is still unsightly and something you want to clean away ASAP. Beyond being unsightly, though, what is soap scum, and how does it get all over our clean bathroom surfaces?

What Is Soap Scum?

Soap scum (also called lime soap) is a white, chalky residue that appears as a white or gray filmy layer that covers the surfaces around our showers, bathtubs, and sinks. Soap scum is made by calcium stearate and magnesium stearate, among other materials, mixing with hard water.

Soap scum can be found on shower curtains, bathroom fixtures, bathtubs, shower doors, tiling, and more. Limescale is often mistaken for soap scum. Though similar, limescale is a hard, off-white, and chalky deposit that is typically found in kettles, hot water boilers, and hot water central heating systems.

How Does Soap Scum Form?

Soap scum is formed into a solid substance when soap is being used in hard water. On a scientific level, soap scum combines calcium and magnesium particles (ions) that are currently in the water with the soap, which forms into the soap scum substance. This formation is frequently caused by minerals in tap water that combine with soap and dirt to create a layer of scaliness over the surfaces in our bathrooms and sometimes even our laundry.

Homes with mineral-filled hard water are much more likely to have soap scum buildup, which can be difficult to remove if left for too long, as soap scum continues to build up each time the area around it is used. Soap scum that is left alone and allowed to build up can combine with mold or mildew and have other discolorations and odors—and can even get as hard as concrete, which just makes it more difficult to remove.

How Do You Remove Soap Scum?

There are long-term and short-term solutions for removing soap scum. Long-term, cleaning your bathroom, and other places with soap scum, frequently is the best way to avoid build-up. There are several short-term solutions available to clean and remove soap scum, many of which serve several purposes beyond cleaning soap scum only. For example, you may want to use the cleaning agent Borax if you are seeking a safe and natural mineral that cleans soap scum, as well as kills and prevents mold and mildew. You may need to do some experimentation to find the best soap scum remover for you.

How Do You Prevent Soap Scum?

The first step to prevent soap scum build-up is to maintain a clean bathroom by removing all soap scum in the tub, shower, and other surface areas as soon as it begins to develop. Applying a gel gloss or car wax to surfaces with soap scum, after cleaning it, will make it more difficult for soap scum to form in the first place. Using a daily shower cleaner can help stop soap scum from coming back, and you only have to spend a few minutes every day on this, using a squeegee or dry rag, depending on your space.

Another soap scum prevention tip is to switch out your bar soap for a liquid or gel body soap, which will stop soap scum altogether. Lastly, preventing soap scum can be both easy and relaxing by sprinkling Epsom Salts into your bath, which makes soap residue go down the drain and stray from sticking on surfaces.​

When removing or preventing soap scum, you may inadvertently find watermark stains in the area that you cleaned. To prevent watermark stains, you can use a weekly cleaner to avoid aggressive scrubbing. Using products like Dawn's dishwashing liquid and white vinegar will do the trick.