A graphic explaining how to spray away soap scum.How Does Soap Scum Cause Plumbing Problems?

When the minerals in hard water combine with soap (and its fatty acids), they create lime soap, otherwise known as soap scum. Difficult to remove, scum builds up over time, attracting mildew and mold. The scum is a nuisance because it can clog your drain.

It’s also gross and potentially unhealthy because it plays host to bacteria. Soap scum can be a problem in the kitchen sink, but it tends to be more common in the tub, shower, and other bathroom surfaces. It’s what turns clear glass shower doors cloudy and leaves a chalky residue in the tub.

How to Prevent Soap Scum From Clogging the Drain

You can remove soap scum from your drains in several ways. If you clean regularly, you’ll remove scum before it grows into a clog.

  • Use Hot Water
  • Clean With Baking Soda
  • Ammonia
  • White Vinegar

Hot water

Boil water and pour it down the drain. This simple action will melt soap scum clinging to the pipes. Follow by running hot water for a few minutes. Read about other ways to clean drains without the use of harsh chemicals.

Clean with baking soda

Mix baking soda and water in a measuring cup and pour it down the drain. Use the ratio of 1 teaspoon of baking soda per 1 gallon of water on the first attempt. If that doesn’t work, bump it up to 1 teaspoon per 1 quart of water (do not exceed 2 teaspoons in one day ). The mixture will quickly eat through soap scum and deodorize the drain.


If hot water didn’t do the trick, pour ammonia down the drain followed by more boiling water, and then flush by running hot water. This method may work if your drain is slow because of scum. When using ammonia as a cleaning product, be sure to run the fan and open a window–its odors can be overwhelming.

White Vinegar

Another option is to get to the soap scum before it gets to the drain. White vinegar can be a very effective and natural way to remove soap scum from various surfaces in your home, such as your bathtub, shower, and sink. Fill a spray bottle with the vinegar and spray the scummy surface. After 15 minutes or longer, scrub the surface with a non-abrasive stiff-bristled brush and then rinse the area.

White vinegar is an acid that breaks down the minerals in soap scum and other buildup, making it easier to remove. Plus, it’s an all-natural and cost-effective cleaning solution that can be used in place of harsh chemical cleaners.

Caution: Never mix chlorine bleach or vinegar with ammonia. They will form a toxic mix of vapors that can send you to the emergency room.

Other Ways to Keep Your Drains Clean

In addition to flushing away soap scum, prevent clogs by taking care of your drains. Here are two simple, cheap, and effective ways to keep your pipes cleaner:

Use a mesh trap: If you’re not using a mesh trap, purchase one for each bath or shower drain. Mesh is the best type of trap for catching soap scum, hair, dead skin, and other things that contribute to clogs.

Don’t use the drain as a garbage disposal: Anything that goes down the pipe can potentially stick to soap scum and worsen a clog. Hair, food, grease, and grooming products contribute to the buildup. A mesh trap will screen out many things, but be careful of what you pour into the drain.

Properly dispose of kitchen grease and scraps by placing them in the garbage or compost bin. Never pour things such as leftover paint or solvents down the drain. Aside from being bad for the plumbing, they contaminate the environment.

What Is Soap Scum?

Soap scum is the solid white residue that clings to bathtubs, shower stalls, drains, and pipes. It forms when dish soap or bar soap and mineral-containing water mix together. Groundwater in the Pacific Northwest contains minerals, but hard water is characterized by relatively large amounts of calcium and magnesium.

Oregon water tends to be soft, but there are plenty of nearby regions, such as east Oregon and Washington state that rely primarily on hard water. Regardless of what area of the PNW you’re living in, soap scum can find a home just about anywhere in your shower or bath.

Portland water: Is it hard or soft?

Portland’s water is naturally soft. The city gets water from the Bull Run Watershed. The Portland Water Bureau serves the tri-county area. If you live in Multnomah, Washington, or Clackamas counties, your municipal water comes mainly from Portland and the Bull Run.

Even though the city’s water is soft, you may still have a problem with soap scum. Many places in Oregon use a mix of sources that combine both hard and soft water. For example, if you’re not connected to public water but instead use a well, you could have hard water.

Whatever the source, if you see water spots on your drinking glasses, you have minerals in your water. You may want to consider installing a water softener to help with the issue. Although it can be done if you’re especially handy, we recommend working with a professional.

Need a Portland-area Plumber to Help With Soap Scum Clogs?

Contact Meticulous Plumbing to help tackle soap scum clogs or any other plumbing problems. We’re a family-owned plumbing company in Portland, Oregon.

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