We’ve all seen them at some point — those little black worms in the shower that collect and squirm around the drain. Maybe you think they’re neat, or perhaps they gross you out, but either way, those things have got to go.

The little black worms in your shower are the larvae of drain flies. They collect near standing water, provided they’ve got a food source, which can be pretty much any organic material.

While they won’t kill you (or even make you sick), the flies and the larvae can be off-putting at best, and at worst, can create some issues with your plumbing. The best course of action involves getting rid of them sooner rather than later.

Why Are There Black Worms in My Shower?

If you’re seeing black worms in your shower, it’s because they’ve got food and standing water. This basic answer is also true about mold, so you will often see the two together in your shower.

The tiny black worms love standing water, and your shower drain has it in spades. It also has mold, slime, hair, dead skin — organic materials they can eat. They go where they can best thrive, and your shower, particularly its drain, is one of those places. More on that in a bit.

Black Worms Aren’t Really Worms

The drain fly larvae look like worms, and they squirm and wiggle like them, too. They range in length from 4-10 mm (0.16-0.39 in), so they’re tiny. Often, you might not even notice one or two of them. But once they’ve built up a presence in your shower drain, you’ll see them wiggling around, especially since their larval stage can last up to 24 days.

Here’s the thing, though — if you see the worms, that means there are a whole lot more that you don’t see.

Drain flies lay their eggs inside the drain, where they can be close to the mold and slime that collects in there. Most often, you won’t see any sign of drain flies until they’ve matured and begun to fly around near your drain.

Again, when your spouse comes and asks, “Why are there black worms in my shower?” You know you’ve got some work to take care of because seeing larvae outside of your drain means a large contingent probably lives inside the drain.

Why They Choose Drains

Like every other living thing, drain flies and their larvae need water for survival, so your shower drain constitutes a good place to find that. On a fairly regular basis, the shower gets used, and the water gets replenished.

The drain itself has organic material in it — whether it’s hair you’ve shed in the shower or the mold and slime that we’re all so disgusted by when we have to work on the drain.

With food and water sources that, in their eyes, will never run out, the drain flies make a home and start laying eggs. Here, we should point out that the best environment for them isn’t just standing water, but stagnant water.

This explains why you might be more likely to discover drain flies after you’ve been away from the shower for a few days, say if you went on a vacation or something similar.

While you were gone, the water stored in your shower drain’s U-trap sat undisturbed while the slime and mold above it continued to grow. You didn’t know it, but you were ringing the dinner bell for drain flies the whole time you were visiting Vermont.

How Do I Know I Have Them?

You will know you have drain flies worms because you can see them. However, they don’t always come out in the open. You’ll know you have drain flies because you’ll see them flitting around, but discovering worms that aren’t visible takes work.

If you see the flies, you’ve probably got the worms, too. If you suspect worms, you can still detect the larvae in the drain with the duct tape test. Here are the steps to check if there are larvae in the drain:

  1. Seal the drain cover with duct tape, making sure the sticky side shows through the open sections of the drain cover.
  2. Put the cover on the drain and wait overnight.
  3. The following day, pull the drain cover off and look at the underside — if you’ve got drain fly larvae in your drain, you’ll see some of the little black worms stuck to the duct tape.

When they try to come up out of the drain for fresh water or some air, or maybe just a little exercise, they’ll get stuck on the tape. Then you’ll know, even if you haven’t seen any of the flies.

Are Drain Worms Dangerous?

Neither drain worms nor drain flies are dangerous. If you have a large group of them, you may be at risk of being exposed to bacteria. Drain worms and drain flies feed on organic material, and that includes sewage.

There shouldn’t be any sewage in your drain, but drain flies can live in other places, too. If you’ve got a septic tank, they’ll love that thing. Also, any soil around your home that has sewage in it will attract them, too. All this is to say that drain flies and their larvae are dirty, gross little guys.

While having them living in your shower drain won’t make you sick, again, a large group of them will be toting some bacteria you probably don’t want to get on your hands and face.

How Do I Get Rid of the Little Black Worms in My Shower?

Ideally, you’d eliminate all standing water and the accumulation of organic material in your shower. That’s not an option, though, unless your shower is non-functioning and just for show.

You can get rid of the little black worms in your shower with chemicals. You can also deal with the problem with more natural solutions, like using materials you have in your kitchen or garage. Many people avoid using chemicals in the shower, where you likely spend a small part of every day.

Of course, if yours is a bad infestation, chemicals probably stand as the better alternative. They’ll do the job quickly and thoroughly. And there’s nothing wrong or harmful in using chemicals unless you’re using them every day. But if you’re doing that, you’ve got more significant problems than a simple drain fly infestation.

Chemical Remedies

Before you go pouring caustic liquids into your drain, you need some information about your drain and about the chemicals you’ll use. These are:

  • Check that your drain works properly. Pour a half-gallon or so of water down the drain to see that it drains as it should. If you already have a clog, you can forgo this step (you’re probably about to pour a drain cleaner in, anyway), but if you’ve not noticed clogging issues before, you want to know beforehand that a problem exists.
  • Don’t mix drain cleaning products. Many of them have highly caustic chemicals in them. Mixing different concoctions can create chemical reactions that can damage your plumbing or even cause you real, physical harm. Remember that sulfuric acid is just sulfur, oxygen, and hydrogen, so it’s relatively easy to create, even accidentally.

Drain Cleaner

Even something as commonplace as the Drano Max Gel Drain Clog Remover (available on Amazon) will get the job done for you. If you have a clog, this stuff should make quick work of it, but even without a clog, it’ll flush out whatever grime, slime, and biological materials in the drain that the larvae like to eat.

A bonus is that since the flies lay their eggs in the slime inside your drain, you’ll be getting rid of eggs, too, before they even let the little back shower worms out into the world.

Drain Fly Killers

If you don’t have a clog, perhaps you don’t want to pour the toxic drain cleaner down your drain. In that case, you have the option of using a dedicated drain fly-killing product. Products such as the Natural Armor Fruit Fly & Drain Fly Killer work to eliminate the slime so the flies have no food source while, at the same time, killing the eggs, larvae, and flies.

While there are several manufacturers of drain fly killer, Natural Armor formulates this with natural products, which means it won’t have any deleterious effects on your pipes.

No matter what you choose, be sure to check the label to ensure you can use it safely where you plan to — drain flies don’t only choose shower drains, so you don’t want to use something in your kitchen sink if it’s unsafe to do so.

Natural Remedies

More and more people don’t want to bring chemicals into their homes or release them into the environment, so the search for non-toxic solutions and home remedies goes on and on. There are natural approaches to solving the drain fly problem.

Baking Soda and Vinegar

Most of us have used baking soda and vinegar. Combining them into a cleaner does a pretty good job. This extends to cleaning your shower drain, and a cleaner drain means less chance of larvae and drain flies. Here are the steps to make a cleaner:

  1. Stir 1 tsp of salt into 1 cup of baking soda.
  2. Pour the baking soda and salt into the drain.
  3. Pour 1 cup of white vinegar in after it (you’ll hear some whooshing sounds as the soda and vinegar react to each other).
  4. Let the mixture sit for as long as you can up to overnight (the longer you leave it, the better it’ll work).
  5. Pour boiling water down the drain to clear the mixture and remove all the gunk.

Boiling Water

Even without mixing stuff from your kitchen together, you can make some progress with just the boiling water. But it has to be boiling water to ensure that it kills as much of the bacteria and larvae as possible. Water that’s just hot won’t do it.

Pour the water down the drain once or twice a day for at least five days. If you still have a problem with little black worms in the shower after that, you’ll want to move to one of the above solutions.

Whatever method you choose, be sure to get rid of anything the larvae need. A cleaner drain means less food for them, so focus on that. Don’t worry about the flies. Getting rid of the larvae means the flies will stop regenerating, and once that last fly bites the dust, your problems are over.

Once They’re Gone

Keeping the drain and pipes clean stands as the best way to make sure those worms or their fly brethren don’t come back. For this reason, you may not want to rely simply on the boiling water method.

The heat will remove lots of stuff, but it won’t do much to cut down on limescale buildup in the pipes, which is one factor in the buildup of organic materials in the drain. Little bits get hung up on the limescale deposits, and accretion just makes things worse.

So once the drain is clean and the flies and worms are gone, you’ll need to pay some regular attention to your drains. While you can use something such as the Green Gobbler Enzymes for Grease Trap & Sewer to bust up a clog, pouring a smaller amount in your drains weekly — perhaps as part of your cleaning routine — will help discourage any buildup.

Alternatively, pouring one cup of vinegar into the drains every week will actively discourage the limescale buildup that can contribute to the drain fly problem. It’ll also help with deodorizing the drains in your home.

Finally, you’ll want to be sure your pipes function correctly, which you’ll know from using them, but also from periodic inspections. If water isn’t draining properly, there’s a good chance that it’s sitting stagnant somewhere in the system and creating fertile ground for the drain flies you just worked so hard to get out of your bathroom.


Drain worms and flies won’t hurt you, but they’re dirty little sewage-dwellers. They come to live in and around drains since those places hold water and the organic material on which they feed. That means they don’t just stay in the shower, and you might also find them in your sinks.

You can get rid of them with commercial drain-cleaning products or natural remedies, and there are products expressly for getting rid of drain flies. Once they’re gone, take steps to ensure the drain flies don’t return. This includes keeping pipes and drains clean and in good working order.

Write A Comment