Moisture left in shower, sink and bathtub drains create the perfect environment for black mold growth. Soap scum, body oil and grime provide a food source, and running more water through the drain just provides more moisture. Black mold can cause health problems such as asthma and rhinitis. Remove the mold 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 mold 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 mold from inside the pipe.
If possible, remove the pipe to access areas out of reach to the bottle brush.
Once all visible mold is removed, clean all the surfaces again with a mold 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 mold inhibiting solution down the drain to kill mold out of reach. This will not kill all the mold, 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 mold 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 mold growth.
Clean drains once a month with a mold 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.