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Tiny Bugs in Bathroom: What Are They

It’s a homeowner’s worst nightmare: tiny bugs in bathroom. You pull back the shower curtain and discover numerous tiny bugs all over your bathtub. What are they? Where do they originate? Most importantly, how do you get rid of them?

They’re more than likely drain flies. Tiny flies that live and breed in the drains of bathtubs and showers. Some other names for these flying menaces are drainage moths, filter flies, and sewage flies. 

What Are the Tiny Bugs?

The tiny bugs are known commonly as drain flies. They’re a variety of non-biting gnats. They are not a cause for concern and are relatively easy to exterminate. You can rest easy knowing that they’re only a temporary problem in your home, even if they are a nuisance.

Where Do Drain Flies Originate?

Drain flies breed in standing water. It’s not uncommon to come home from a long vacation to find them having reproduced in your home. In most circumstances, you’ll see them disappear in a few days to weeks as regular use of the drains resumes; and their nests are flushed away.

However, there are circumstances in which they may stay and continue to multiply. If you’re dealing with a sustained infestation of drain flies, that can be very annoying. Thankfully there are methods to clear out their breeding spots so you can have relief.

Sustained Infestation

Drain flies can be anywhere that there’s standing water. They can nest in the slime layer that may develop in less often used toilet bowls and tanks, bathroom or garage drains, or evaporator pans underneath refrigerators. 

Like the fly itself, the larvae can be minuscule. Because of their size, it can be challenging to determine where they’re breeding by inspecting the site alone. What you can do to find them is set up fly traps. A small cup of water with a drop or two of oil will catch them. When you find a high enough concentration trapped in your cup, you’ll know their source and can get to work.

If you don’t, you’ll need to expand your search area to find them. Remember, check near drains and toilet bowls. These are your most likely culprit.


Many homeowners believe the proper solution to drain flies is to pour bleach down the offending pipe. But this is not the case; it’s not effective at all.

Because drain flies will lay their eggs in the thick slim layer that develops in pipes, bleach will pass through too quickly and not penetrate and destroy all of the eggs. Additionally, bleach is corrosive and can damage your pipes.

You shouldn’t combine bleach and ammonia; this creates chlorine gas which is fatal to your health if inhaled. 

Another common mistake is to try and use Drano to destroy the larvae (see our post about putting drano down the toilet for more information). While this is excellent for clearing away the gunk lining your drains, it’s not guaranteed to destroy all of the eggs. 

Instead, if you’re suffering from a persistent outbreak of drain flies that won’t go away with the regular use of the drains, you can call a professional exterminator. There are enzyme foams that a professional will safely apply to pipes.

The foam will be shot into your pipes, expand and penetrate the slime layer. It will break down the slime and the eggs laid in it.

Ultimately, you may find that the flies continue in your house for several more days. Because drain flies can live up to twenty days, you may see the adults longer than you would like. Thankfully once you break the egg into the adult life cycle, the infestation will die off.

Professional Exterminator


These tiny bugs will breed in the sludge and slime in your pipes, especially if there’s any stagnant or standing water in them (if you spot flies in your bathroom, check out our guide on drain flies). The best solution is to try and keep them relatively clean by regularly running water through them. 

Other solutions include making a solution of vinegar, baking soda, and salt and flushing that down your pipes. This solution is a non-corrosive way to break down the breeding sites of these flies. 

How to Get Rid of Drain Flies

What Other Tiny Bugs Could Be in My Bathroom

If not drain flies, what else could be lurking in your bathroom? Let’s find out.


These pests are attracted to warm, moist environments. A bathroom is an ideal location for cockroaches. They like to occupy drains and other similar places.  If you suspect cockroaches are in your home, you should promptly contact a professional exterminator to assess the situation. They can spread disease and filth and are not at all welcome house guests.

Stink Bugs

You may spot these insects trundling through your bathroom when it gets cold out. They’re not harmful but are simply overwintering in your home where it’s warm, they usually stick to interior walls.


An elongated insect with a silver body, this insect is easy to spot. The silverfish thrives in warm, moist environments. If you find high numbers of these bugs in your home, it would be a good idea to investigate. It could mean that you have water damage.


While many people don’t like the sight of spiders, they’re beneficial. They’ll catch and eat nuisance bugs, so spotting the occasional spider shouldn’t be cause for concern. The method to keep their population low in your home is to limit their food source. 

House Centipedes

These are other predatory insects that are found in your room. They prefer moist, dark places. But it isn’t unusual to find them lurking in bathrooms, seeking an abundant food source. Like spiders, the way to see less of these is to reduce the number of prey for them to feed on.

General Pest Deterrent

We’ve covered in greater detail what you can do to deter drain flies. But we have some more tips that will be beneficial to deal with them, along with other pests.

Seal Entrance Points

Perform a visual inspection of your bathroom. Check to see if there are any points of entry that insects may be used to get into your room. Windows are a common culprit, inspect the molding and see if it needs to be sealed.

Limit Moisture

Virtually all of the pests we’ve talked about thrive on moisture. It can be challenging to eliminate moisture in a bathroom, but you can limit it.

Limit Moisture in Bathroom

Fix Plumbing

It’s not uncommon for there to be plumbing problems in a home, especially an older house. If you notice more pests in your bathroom, you should inspect the plumbing around your sink or bathtub. There may be a leaking pipe, creating a moisture issue.

Not only do leaking pipes create an attractive environment for all kinds of pests, but they can also be detrimental to the structural integrity of your home and should be addressed promptly.

Clean and Declutter

Make it a habit to regularly clean and declutter your bathroom. Cleaning will reduce possible food sources for insects, and decluttering will leave them with fewer places to hide.

Frequently Asked Questions

If you still need some more information about tiny bugs in the bathroom, check the answers to some common questions.

Can drain flies be killed without chemicals?

Yes. It’s possible to eliminate drain flies without the use of harsh chemicals. You can find their breeding grounds and destroy them, then the life cycle will be broken. Some adults will linger, but should eventually die off.

Can drain flies be found outside?

Yes. You can find drain flies outdoors. They may be a sign of faulty septic lines, areas where rainwater is pooling, or a place where air conditioner water is pooling.

Can bug spray kill drain flies?

You can use aerosol sprays to kill adult drain flies. However, this will only give you temporary control of the problem. You must find the source and eliminate them.

Will drain flies bite me?

No. Drain flies are non-biting gnats and do not have any interest in biting humans. They live off of the slime and sludge found in stagnant water. They are largely considered to be a nuisance but not physically harmful.

Are drain flies hazardous?

Drain flies originate from unsanitary sources and should be eliminated quickly to limit the spread of any disease or illness. 

Tying It All Together

In the event you start finding numerous tiny bugs in bathroom, the chances of them being drain flies are high. You’ll need to address the issue by removing their food source and eliminating breeding grounds. 

The good news is that once you break that cycle, you shouldn’t have to worry about them anymore. The adults will die off, resulting in you being pest free.

You may have other bugs in your bathroom, but if you follow our suggestions, you should see a decrease in them.

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