How to Naturally Get Rid of Drain Flies: Effective Ways that Really Work

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How to Naturally Get Rid of Drain Flies: Effective Ways that Really Work

Drain flies are annoying flying pests that you might notice around your sink or shower drains. Drain flies are sometimes called moth flies, sewer flies, sink flies, or sewer gnats (Psychodidae) and they inhabit the dark, damp conditions in drains. You will most likely notice these tiny flies in kitchens and bathrooms where they feed on decaying organic matter in drains.

Getting rid of drain flies naturally is fairly easy. Once you disturb their environment and make sure that drains are clean and dry, your problem of a drain fly infestation should disappear quite quickly. However, it’s important to make sure that your fly problem is with drain flies, not fruit flies. As both of these fly species are tiny, it’s easy to confuse them.


To make sure that you eradicate drain or sink flies for good, it’s important to know something about their habitat and behavior. This can help you target their breeding grounds and prevent these pesky flies returning.

In this article, you will find out how to naturally get rid of drain flies. First of all, let’s look at what drain flies are and how to identify the tell-tale signs of a drain fly or sewer fly infestation.

What Are Drain Flies?

The Entomology department at the University of Kentucky says that drain flies are small non-biting gnats that have dark wings. The tiny drain gnats or moth flies don’t just fly around drains. You may find them lurking on your walls or ceilings near drains.1

Dr. Subba Palli from the University of Kentucky says that if you notice many drain flies over several weeks, it means that they may have a permanent breeding site. To get rid of the flies for good, it’s essential to find and destroy their habitat.1

It’s not just in drains where these sewer gnats like to live and feed. According to Dr. Palli, they can live anywhere where water accumulates. This could be in toilet bowls, water tanks, floor drains, or under refrigerators.

Life cycle and habits of drain flies

Drain flies can quickly become a nuisance in your home and before you know it, you have a large number of flies infesting your property.


The Ohio State University says that drain flies lay their eggs anywhere where there are moist organic solids. Larvae can appear up to 48 hours after the eggs have been laid and will become mature adult drain flies in 9 to 15 days. Adult drain flies live for around two weeks. Because of their shape and wing formation, drain flies are sometimes called moth flies.2

Are drain flies harmful?

Although drain flies don’t bite and generally don’t carry infections, they are associated with some health issues. The effect that drain or sewer flies can have on your health is yet another reason to remove these gnats from your home.

The American Review of Respiratory Disease reports that sewer flies have been known to cause asthma in people who are frequently exposed to these flies.3

A study in Germany found that drain flies, or moth flies, can also carry bacterial infections. Among the bacterial strains that were found on drain flies were Escherichia coli (E. coli), Pseudomonas aeruginosa, and other antibiotic-resistant pathogens.4

Signs of a Drain Fly Infestation

The first step to getting rid of drain flies for good is to know the signs of a drain fly infestation. Drain flies are weak fliers and will usually be found close to where they are living. So, look for drain flies on walls and ceilings near drains.

The University of California recommends making a fly trap to find out where your drain fly infestation is coming from. You should coat the inside of a plastic cup with vegetable oil and place it inverted to cover the drains in your home. Any drain fly coming up will stick to the vegetable oil.5

If this fails to uncover the source of the drain fly problem, then the drain flies may be living in crawlspaces, wall voids, or under concrete slabs where water is accumulating.

How to Get Rid of Drain Flies Naturally

Of course, you can easily get rid of drain flies by swatting them. However, this doesn’t solve the root of the problem. To eliminate drain flies for good, you need to destroy the environment in your drain where they are likely to feed and breed.

Once you have identified the drain where the drain flies are breeding, you can now start to get rid of the flies. Here are some effective natural methods of exterminating sewer flies.


Use a metal pipe brush

Keeping your drains clear of decaying debris with a metal pipe brush is a cheap and effective way to get rid of drain fly infestation. The metal pipe brush helps to destroy the breeding source by removing all grime, slime, and debris where the drain flies can lay their eggs.

How to use:

To clear your drains and prevent drain flies from laying more eggs, please do the following:

  • Work a metal pipe brush into the drain.
  • Slowly move the brush up and down, twisting it at the same time.
  • This helps to dislodge grime and dirt from the sides of the pipe and also remove the drain flies and their eggs.
  • Pour plenty of hot water down the drain to flush out all remaining clumps of grime.

Alternatively, you can use a plumbing snake to clean your drains from a buildup of debris and slime and help control your drain fly infestation.

After cleaning out the drain, you should then use the vinegar and baking soda solution to help kill any drain flies that are left over.

Vinegar and baking soda

A mixture of vinegar and baking soda is an effective and natural way to get rid of flies from your drain. Vinegar is a natural antiseptic agent and it reacts with baking soda to create a bubbling foam. This can help to kill off drain flies and their larvae.

Vinegar may also help to destroy the bacteria buildup in the drains which attract the flies. The University of Maryland published a report on the acidic properties of vinegar in weed control. The researchers found that vinegar helps to break down plant matter and is good for controlling pests.6

How to use:

Make a drain cleaner with vinegar and baking soda to kill drain flies by doing the following:

  • Mix 1/2 cup salt and 1/2 cup baking soda and pour into the drain.
  • Pour in the drain 1 cup of white vinegar.
  • Allow the mixture to work overnight to kill off all the drain flies and destroy their environment.
  • In the morning, pour a pot of very hot water down the drain to put an end to your drain fly problem.

You can also use vinegar to prevent drain flies inhabiting your drains in the future. Just pour one cup of white vinegar down the drain weekly. Allow the vinegar to sit for 30 minutes, then flush the drain with water. This will also help to prevent your drain starting to stink from a grime buildup.


You need to be aware that even after cleaning the drains, you may still have adult flies and they will live for about 15 days, but since they will have no place to lay eggs, the problem will disappear when they die. If you want to kill the remaining adult drain flies, use the following traps, baits and natural fly spray.

Vinegar and sugar drain fly trap

You can also make a vinegar and sugar fly trap to attract drain gnats from drains and kill them naturally. The vinegar and sugar fly trap also incorporates liquid dish soap to help eliminate these pests for good. Soap also has insecticidal properties and is also an effective way to kill various types of cockroaches.7

The sweetness of the sugar attracts the drain flies and the soap causes them to drown in the water.

How to use:

To make a natural trap to get rid of drain or sewer flies, this is what you should do:

  • In a bowl, mix equal quantities of sugar, water, and white vinegar.
  • Add 10 drops of liquid dish soap and mix well.
  • Place the bowl with the vinegar and sugar mixture next to your infested drain.
  • In the morning, you should have some dead drain flies floating in the mixture.

Please remember, that this will only get rid of adult moth flies or drain flies. You will still have to clean out the drain to completely remove all traces of the tiny, annoying flies and their larvae.

Natural apple cider vinegar fly trap

Another tried and tested method of getting rid of flies, including drain flies is to make a trap with apple cider vinegar (ACV). Apple cider vinegar makes an effective fly trap because the acetic acid has insecticidal properties. ACV has a sweeter smell than regular vinegar and this lures the drain flies to the trap.

The sewer flies or drain flies will get into the trap through the hole and not be able to get out again. The apple cider vinegar will kill the flies for good.

How to use:

It is very easy to make a natural drain fly trap to help control the infestation. All you need is a jar, apple cider vinegar, and some plastic wrap.

  • Pour about 1/4 cup apple cider vinegar into a jar or glass.
  • Cover tightly with plastic wrap and pierce some holes in the top.
  • Place the vinegar trap next to the sink where the drain flies are inhabiting.
  • Leave the trap out until you no longer have any drain flies coming out from your drain.

Thieves essential oil fly spray

There are many ways to use thieves essential oil and one of them is eliminating drain flies. Thieves essential oil is a mixture of 5 essential oils – clove, rosemary, cinnamon, lemon, and eucalyptus – that have antimicrobial and insecticidal properties. For example, clove oil is effective against pests and insects.8 Cinnamon oil is a natural pesticide and is also effective at repelling mosquitoes naturally.9 Studies have also shown that eucalyptus oil is an effective natural pesticide.10

How to use:

Many people have reported that a few drops of thieves oil in the drain helps to kill off flies and their larvae.

  • Put 1-2 drops of thieves essential oil in each drain where you think you have drain flies.
  • Cover the drain with a plastic cup (or any kind of bowl) to help prevent the oil vapors escaping.
  • Repeat as necessary until you no longer have drain flies coming out your drain.

Essential oil spray for killing drain flies

You can also use an essential oil spray to destroy drain flies naturally and safely. Many essential oils contain insect repellent properties. They are toxic to flies, insects, and can help get rid of ants, but can safely be used around the kitchen and bathroom.

You can use any of the essential oils used in the thieves essential oil fly spray because they all have proven efficacy against insects. Other great essential oils for getting rid of pesky flies are:

How to use:

All you need to make a spray to get rid of drain flies for good is a few drops of essential oil, some liquid soap, water, and a spray bottle.

  • Fill a spray bottle almost to the top with water.
  • Add 5 – 10 drops of your favorite essential oil. (You can use just one, or experiment with a combination to get a smell that you love).
  • Add 1-2 drops of dishwashing liquid.
  • Shake well.
  • Spray on the drain flies to kill them. You can then wipe the surfaces with a clean paper towel to remove the dead flies and clean the surface.

How to Prevent Drain Flies from Returning

Once you have completely got rid of all drain flies and eliminated their breeding sites, it’s important to take some steps to prevent another infestation.

  • Once you have resolved a drain fly infestation, clean your drains weekly until you are sure that there are no more eggs, larvae, or flies in your drain.
  • Use any of the above drain fly removal methods to help keep drains gunge-free and prevent a buildup of grime and dirt.

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Article Sources:
  1. Entomology CA UKY. Drain flies or moth flies.
  2. Ohioline OSU. Drain flies.
  3. Am Rev Respir Dis. 1985 Jun;131(6):949-52.
  4. J Hosp Infect. 2013 Jan;83(1):51-60.
  5. IPM UCANR. Moth or drain flies.
  6. UMD. Vinegar: an alternative to glyphosate?
  7. J Econ Entomol. 2002 Apr;95(2):390-8.
  8. PLoS One. 2010; 5(8): e12079.
  9. American Chemical Society. Cinnamon oil kills mosquitoes.
  10. EC Europa. Eucalyptus oil as an alternative to chemical pesticides.
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