How to eliminate black mold in a drain

Updated February 22, 2017

Moisture left in shower, sink and bathtub drains create the perfect environment for black mould growth. Soap scum, body oil and grime provide a food source, and running more water through the drain just provides more moisture. Black mould can cause health problems such as asthma and rhinitis. Remove the mould as soon as possible to prevent it from causing problems for anyone in your house.

Turn on a fan or open a window for ventilation.

Run water down the drain. If the mould is dry, spores can be released into the air when you run the water.

Scrub the outside of the drain with an old toothbrush or cloth and a mild cleanser.

Remove the drain grate, if possible, and scrub the underside of the grate with a cloth or old toothbrush.

Use a bottle brush and soap to clean mould from inside the pipe.

If possible, remove the pipe to access areas out of reach to the bottle brush.

Once all visible mould is removed, clean all the surfaces again with a mould inhibiting solution, such as a mixture of 1/2 bleach and 1/2 water, or straight vinegar. Use a cloth or bottle brush to wipe surfaces with the solution.

Pour mould inhibiting solution down the drain to kill mould out of reach. This will not kill all the mould, unless the solution comes into contact with all areas of the drain pipe.

Reduce humidity in the room to a level below 55% to inhibit mould growth. Run a fan during a shower or bath and for five minutes after use. Open a window for ventilation. Wipe wet surfaces after using a sink, shower or bathtub, especially around the drain.

Turn on a light. Light discourages mould growth.

Clean drains once a month with a mould inhibitor like vinegar or a mixture of 1/2 bleach and 1/2 water. Spray the sink, shower or bathtub with vinegar. Do not rinse.

Things You'll Need

  • Cloth
  • Old Toothbrush
  • Bottle Brush
  • Cleanser
  • Mold Killing Solution (such as bleach or vinegar)
  • Plastic Bags
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About the Author

Alice Drinkworth has been a writer and journalist since 1995. She has written for community newspapers, college magazines and Drinkworth earned a Bachelor of Arts in journalism from the University of Wisconsin and won a media award for her in-depth coverage of local politics. She is also a certified master gardener.