Drain flies in a bathroom: Causes and HOW To Remove them?

Do you ever see flies in your sink or toilet? If you do, then you’re probably not the only one. Millions of people have noticed that their drains have flies in them. They might look more like moths than flies. While they live in dirt and sewage, they are generally not believed to be harmful.

They don’t bite or sting. In rare exceptions, the larvae (or worms that later become flies) can go under the skin though. Given that these flies live in the drain, they can be dirty and make people uncomfortable.  They can be a nuisance as they show up in great quantities. Let’s discover what they are and how you can get rid of them.


What are Drain Flies or sink moths?

Drain flies are small, black flies that live in water. They have wings and can fly around. They can multiply very rapidly as the females can lay a ton of eggs. These eggs turn into worms that later become flies. They can be found anywhere from a sink, garbage disposal, shower to toilet. They eat organic waste (such as crumbs or leftovers of vegetables). 

 There are several species and while in most instances they won’t harm you, they are covered in sewage and this can lead to a bad reaction. Therefore it is essential that you remove them as soon as possible. 

It is essential that you find where they live and remove them all or they might reappear. Some companies specialize in getting rid of them. They have special equipment such as gasses that they can send in the drains. 

Owl midge by David Short https://www.flickr.com/photos/14583963@N00/17340069882/in/photolist-2gBVtyd-2gBVtuF-s8SKpA-8Qm6Ut-sqhoE7-tUdZVi-ksoiP9-hRdxum-9U9hP6-8HtMDd-s2vXJk-s4fM8u-s4oPP6-s2vY7e

Where do drain flies live?

 They live mainly in standing water and sludge. This makes it essential to open your faucet from time to time so that these flies don’t stand a chance. This also keeps your p-trap wet and makes sure that no nasty smells get in your house.

Opening all your faucets every few days and letting some water run is a great idea as it maintains your plumbing system and can help to keep drain flies away. You also might have to clean the drains under your sink, shower drain, toilets and garbage disposal as they can live in the residue that is left behind.

They mainly come out during summer. If you see them during winter, it can indicate that you have a lot of them and that there is a sewer leak. They love heat and leaking water can offer them this.

Given that they just need warmth and some (organic) food, they can live in multiple places in your house.

Does bleach, soda or hot water kill drain flies? How to solve the issue

 No, they are going to come right back if you just use bleach, soda, or hot water. You need to address the root cause of the problem. People often want easy solutions but drain flies require more work than just pouring liquids in your drains. After you use these liquids, you have to be careful when you open the drains up as these liquids can still be present. 

You can vacuum them up. They will come back though if you don’t remove the source of where they come from. 

The first step is to look under your sink and open up the drains. We have discussed how this can be done HERE. You have to clean the sludge in your drains (also called a biofilm)  and garbage disposal. You can use a brush to clean the pipes. Replacing the garage disposal is often the best idea. Once this is done, you can use an enzyme to further clean it.  These solutions target the food source of these flies. They remove organic waste so that the flies are not able to eat and spread. You might have to clean multiple sinks. Don’t forget the overflow hole in the sink! It all comes down to some cleaning.

 It is also possible that a thorough inspection is necessary that can find the source of the problem. Sometimes the problem is farther in the drain and pouring liquids in the drain might not help that much. They might live under your slab as well and this can require further work. You might have to tunnel under the house to fix this if it is a drain leak.

There can be some odor left and you might have to remove this as well. 

Do septic tanks attract drain flies?

Yes, septic tanks can attract drain flies. These fly-like creatures are attracted to water and septic systems because they need to eat waste to survive. They may also show up in your sink and toilet as they try to find food. If you see a lot of fly-like creatures in your drains, it’s probably best to call a professional to clean things out.

Septic tanks have to be maintained well. This involves only flushing the allowed items. You should also inspect the tank to make sure that it isn’t leaking and that the lid is properly installed. This can avoid drain flies or at least reduce them.

Be careful with chemical products against drain flies around a septic tank as this can interfere with its processes.

Septic tanks are often outside so it doesn’t matter too much. P-trap should stop the drain flies from coming in. If your sink is clean, they don’t have food and can’t grow. Therefore it is generally not a problem that they live there and the worms can be even useful in your tank.  

Getting your septic tank pumped empty can also help to remove drain flies as you remove their food. In some cases, more cleaning can be needed. You can use a pressure washer on some parts of your septic system for this. You can also inspect your septic system to make sure that there are no leaks or other problems.

Will rid x kill drain flies?

Rix-X are enzymes and bacteria that you can add to your septic system.

It has been used for more than 50 years and can break down grease, toilet paper, and more that is stuck in your drains or in the septic tank. As they mention on their website, they are not able to make claims about how fast this process will work as each septic system is different.

While Rid-X might help with breaking down some sludge in the tank, it probably won’t remove or kill your drain flies. Drain flies don’t need a lot of sludge to live in. Once they are present in your tank, you might have to remove the sludge completely before you get rid of the drain flies.

This can involve quite a lot of cleaning and pumping the tank. This is a lot of work. A plumber can use a camera to inspect the septic system and see if there are cracked or broken drains.

While it seems tempting to add a product to the septic tank and get rid of the drain flies, in reality, it generally doesn’t work and you will have to take additional steps to get rid of drain flies.

If there is a big problem with them, you can hire a specialized company. These companies have special products for this. At the same time it is important to avoid harsh chemicals in your septic system as this can break the process down.

Drain flies in the bathroom

Image of a drain fly in a bathroom. Picture by PlumbingInstantFix, all rights reserved

All this sludge can house drain flies. It is only by cleaning this that you might get them away. As discussed, they might live in your sewage system farther away and a camera might be needed to find them. If they live in your bathroom, there is a big chance that the problem is the shower or sink though.

Pipes are often connected and once they live in your shower, they can also live in your sink. It is better to clean too much in this situation than not enough as you might have to start from square one if they come back.  It is a great way to refresh your bathroom anyway as dirt needs to get removed from time to time.

Does a plumber remove drain flies?

Some plumbers might do this but in general, you have to contact specialized companies to help with this. Plumbers fix broken drains and equipment. They generally don’t deal with flies as they are already very busy.

They can help to find the root cause of the issue with a drain camera though and can fix drains if needed.  In some states, you might need to have a license to deal with these flies.   

Drain flies can be annoying. Removing them from a bathroom can take quite a lot of work. You will have to remove some fixtures, open up drains and clean them out. Drains can contain a lot of sludge and cleaning this out is not an easy job.

Make sure to get references when you hire a company for help with this as a lot of people claim that they can fix the issue but they don’t use the right techniques.

Drain flies can spread quite fast over your house and won’t disappear without taking action.

We have discussed how to deal with centipedes in your bathroom here.

There are other reasons why your bathroom might smell bad as well.