Mold & Tiny Black Worms Are Living in My Shower

A number of pests and problems can originate in your shower. Showers are warm and damp, which creates the perfect breeding ground for mold and drain flies. Drain flies will lay their eggs inside the drain or on your shower floor. When these eggs hatch, the larvae look like tiny black worms. Mold can also grow anywhere where there is water and enough dust, dirt or soap scum for it to eat.

Woman under shower
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Black Worms

Drain in shower on tile floor
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Shower drain

Drain fly larvae are black and may resemble very small worms. They can come out of your drain or live on your shower surface. The drain fly likes moist conditions and lives in standing water. This makes the standing water in your u-trap piping a common place for drain flies.


Locker Room Showers
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Shower tile

Mold is a plant fungus that decays organic matter. It will settle in areas with excess water, such as your laundry room, bathroom or shower. When this happens, the microscopic mold spores will begin to reproduce to form visible mold growth. Once they do, they send out spores to start new colonies. This is why you often see several circles of mold in an area on your shower curtain or tile.

Prevent Drain Flies and Mold

Close-up of water flowing through drain in sink
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Drain and water

Prevent drain flies and mold in your bathroom by solving the moisture issue in your home. Prevent flies by keeping your drains unclogged so that the drains can flush with water freely. Clean out your pipes with a drain cleaner every few months to ensure that any small larvae are killed before they can hatch and infest your home. Install a dehumidifier to remove excess moisture from the air to prevent mold.

Cleaning Mold

Man cleaning shower wall
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Man cleaning shower

Clean mold residue up with a bleach-based mold cleaner. You can make your own by mixing one part bleach to 10 parts water. Apply the solution to the mold and let it sit for 10 minutes before scrubbing it up with a scrubbing brush. Be careful not to scratch the shower surface by using a stiff-bristled brush. Rinse the area to remove the bleach residue. Bleach is safe for ceramic tile, porcelain or fiberglass showers, but you should be careful when using it on a stone shower as it may cause discoloration.