how to get rid of drain flies: photo

Drain flies are small flies which have different names such as sewer flies, moth flies, sink flies, sewer gnats etc. They love dampness and live near the kitchen sinks, bathrooms, drain pipes, sewage pipes, compost and septic tanks as well as indoors. These flies trouble people as they may be inhaled (wholly or partially) by the human beings when breathing. It is necessary to get rid of these insects in order to avoid the drain fly infestation and harm caused by sewer flies. Here you'll know how to get rid of drain flies and find 5 best products to kill sewer flies in your bathroom and kitchen.

We are eager to equip you with the most essential knowledge on the matter. Trust us, if you learn about the behavior of these insects and choose the right fly prevention and extermination methods, they will leave your house soon.

Table of Contents:

3 Best Drain Fly Killers

Brushtech super flexible drain brush: photo

Invade Bio Drain Gel 1 quart: photo

Invade Hot Spot Bio Foam: photo

Brushtech Drain Brush

Invade Drain Gel

Invade Foam

Removes slime from pipes, where flies breed

Natural killer of larvae and adults in pipes

Fast killer for hard-to-get places

Effectiveness: 6

Effectiveness: 10

Effectiveness: 9

More drain fly killers you'll find in TOP-5 Best Products Review.

Different types of flies are seen flying in the houses. Among these types, there are fruit flies and drain flies. It is confusing for some people to distinguish between them. The distinction lies in their habitats. 

Flies in my house: Fly Identification

  • If “fluffy” moths fly out of your sink, they are drain flies. They love humidity and garbage and can be found somewhere damp.
  • If they swarm in the flowers, most likely they are fungus gnats (read if you want to know how to get rid of fungus gnats).
  • If the moths have occupied fruit, stale beer, soft drinks or other alimentary products, they are definitely fruit flies. Read our review to find out how to get rid of them with the best fruit fly trap.

What Do Drain Flies Look Like?

We call these insects differently: drain flies, sewer flies, moth flies, bathroom flies… Different names are given to the same species. Drain flies are small (<2 mm) with short, hairy bodies and wings giving them a "furry" moth-like appearance. The adults have long antennae and the wings are leaf-shaped, either slender or broad.

It’s much easier to distinguish moth flies by their behavior rather than by their colour or size. Drain flies are active in the evening, and in the daytime these flies are not active and remain clinging to the walls of their habitat. Moth flies are of black color and fuzzy appearance.

They fly poorly therefore they are mostly found indoors, crawling, and taking very short flights at a distance of just a few feet. It is distinctive that few adult species are seen flying since sewer flies live only two weeks.

drain flies control: photo

The life cycle of drain flies contains following stages. The adult flies that emerge from the pupae are fully mature, can reproduce and starts lay eggs after emerging. Approximately 30-100 eggs are laid by the drain fly females. Moth flies eggs hatch in about 48 hours.

Breeding Sites | Inspection & Control

  • During the larvae and pupae stages they need moisture and live in slime layers found in drainpipes, field lines, toilet bowls and septic tanks. The drain fly larvae feed on the microscopic animals and plants, decaying matter and sediments. The duration of the larval stage is about from 9 to 15 days while the pupa stage lasts 20-40 hours. Drain flies house infestation is extremely problematic for those who live in the said house. 
  • Garbage in the kitchen drains, clogged and unclean sink drains, and clogged pipes that are no longer in use and indoor houseplants are some of the places which may potentially attract drain flies.
  • Prevention is pretty straightforward: you have to clean regularly all of the sinks and drains at your place.
  • Examine the whole draining system, as well as any pipes with standing water both indoors and outdoors. You should arrange preventive clean-ups of sewer pipes once a month, especially if your accommodation and sewage system are rather old.
  • Flies don’t fly far away from the place they chose to be their home, that’s why infesting the entire house occurs fairly rare. This is especially true if you start eliminating them as early as possible.
  • Use a metal brush when cleaning the pipes. Clean them with the brush as deeply as possible. Don’t rely on chemicals only: you can’t do without some physical impact. Move the brush-up and down in order to clean the dirt off the pipe walls. It is desirable to hang the brush on a metal rope.
  • After cleaning the pipes you’ll only destroy the place where the drain flies lay the eggs, and you’ll still have to exterminate the adult species approximately for the next 20 days. Don’t worry when you see them, everything is perfectly normal; just make sure you systematically kill them.
  • Always store the food in the airtight containers so that no drain flies could land on it. They only live in the sinks, and they could fly anywhere for food. There might be a battle between the drain flies and the fruit flies for the food left in the kitchen!

How to Get Rid of Drain Flies in 6 Steps | Cleaning the Drains

As the scientists from the University of California Statewide IPM Program claim, the key to removing drain flies is in eliminating their places for mating. The first (and probably the main) stage of getting rid of moths is cleaning the pipes. Although this is a preliminary stage, it is crucial, because if you don’t carry this out, you won’t ever remove these flies even with the help of special products.

Brushtech super flexible drain brush: photo

  1. Identify your “enemy” and its breeding ground. Place some duct tape along the sink (preferably as close to the drain as possible). You may even actually partially tape it. If you don’t see any dead drain flies the next morning, move on to the next step. You can also make a homemade drain fly trap using the IPM recipe. Take a small jar or a cup and grease its edges and inner part with oil, grease or petroleum jelly. You’ll get a sticky trap to cover your sink with for 24 hours. Examine the catch afterwards. If there were drain flies down the drain, they will have been trapped.
  2. Check the basin. The scientists recommend removing the drain plate and scraping slime off all sides of the sink with a blunt knife or another tool. Check the slime for pest larvae. If there are none, the insects must be breeding deeper down the drain and feeding on rotting organic matter there.
  3. Mechanical cleaning. Clean the pipes with the help of a stiff, long-handled brush. Make sure that no hair, food remains or nothing else of organic origin is left there. You may use for this purpose the best selling Brushtech Super Flexible Drain Brush ($10.91), which is a versatile and flexible brush for cleaning the pipes.
  4. Slowly pour the boiling water into the drain: one pot of hot water will be enough. It will destroy a significant amount of larvae and eggs. However, the University of Kentucky entomologists believe it will have a temporary effect as drain flies will multiply again soon enough.
  5. Poor the pipe cleaning detergent (drain cleaner) like Drano ($12.24to remove slime, clogs and organic matter. Make sure you read the manual beforehand and follow it, though. You might have to pour the gel several times a week.
  6. Kill the remaining living moths with the fly swatter!

Use the professional products only after having cleaned the pipes. We’ll describe the drain gels, aerosol insect growth regulator and other useful products against moths.

How To Kill Drain Flies: Best Drain Gels

So, first you have to clean pipes – look at the most effective gel.

Invade Bio Drain Gel  

Bio Drain Gel (rated 4 out of 5 stars on Amazon) is the most popular gel. Depending on the volume, its price varies from ~$13.18 for 1 quart to ~$133.99 for case (which contains 4 Gallons). We recommend you to purchase a gallon for ~$39.99: this will be enough for fighting with the drain flies for a long period of time.

Invade Bio Drain Gel – 1 qt
Invade Bio Drain Gel – 1 qt

Invade Bio Drain Gel is the best selling and the most effective drain gel today – just pour it into the sewer and wait. Most of the customers note the exterminating effect after the first use. Drain flies have no chance to survive!


The only way to apply this gel is to pour it into the sewer (4-5 ounces will be enough for the first time though you’d better read the manual first). The gel does not contain any aggressive or dangerous chemicals, but we do advise you to avoid any skin contact with it, so make sure you wear protective gloves. Citrus oil makes up the luring liquid (its smell is rather pleasant) as well as the “natural germs” which destroy everything on their way, be it something organic, spume or odors.

As a result, the flies’ larvae don’t have anything to feed on. Most of the customers note the exterminating effect after the first use of Invade Bio Drain Gel. Repeat pouring into the sink is still necessary and is recommended by the manufacturer. In any case, most of the users had almost the whole bottle of the gel left after killing all of the drain flies, which makes this quite cost-saving.

Among plenty of positive feedback, we have found a couple of reviews which state that the product is completely ineffective. Perhaps their authors have simply mixed up the drain flies and the fruit flies.

Price: from ~$13.18 (for 1 quart) Check the current price

NB! For hard-to-reach-areas that provides a good development site for drain flies (under the bathtub, under the washing machine, drain pans under refrigerators, beneath drain and sewage pipes) use Invade Hot Spot Bio Foam. This product for ~$18.58 is the good choice for getting rid of drain flies in hard to reach wet areas where you can't apply gel.

For septic tank treatment use RID-X ($16.88). Natural bacteria and advanced enzymes break down paper, protein, oils & grease.

RID X Septic Treatment: photoInvade Hot Spot Bio Foam: photo

Drain Gel

Drain Gel is probably the main rival of the previous bio gel. A gallon of this gel costs ~$37.21, and a quart costs ~$14.96. All in all, the prices are comparable. This product’s Amazon rating is a bit lower as it is 4.1 stars out of 5.

It also decomposes the organic matter inside drainage systems and provides for the healthy environment in the pipes and drains by reaching the smallest cracks and curves. It works well against both flies and other insects. It doesn’t have such a wonderful orange smell, but it destroys unpleasant odors.

drain gel: photo

The users note that the gel is very cost-saving, it kills the entire population of flies after two usages (take into account the fact that it is recommended to pour 1-2 ounces of this gel). Many consumers got hooked on Drain Gel and use it a preventive measure. They claim that monthly sink clean-up with this product prevents “the relapse” of moths.

This product is very similar to the previous one and lets you save $3 when buying a gallon in comparison with a gallon of Bio Drain. In order to understand whether you need Drain Gel, read some customers’ feedback.

Price: ~$37.21 Check the current price

Bathroom Fly Extermination | Best Drain Fly Killer

When drain flies are especially active, the drain fly killers might come handy. They complement the traditional ways of exterminating them as well as professional solutions. Such insecticides which restrain the development of insects and which come as aerosols and poison can be easily combined with other products. What have the insecticide manufacturers got to offer?

Gentrol Insect Growth Regulator (IGR) 16 oz can

Gentrol Insect Growth Regulator: photo

This drain fly killer with Hydroprene (insecticide) is a versatile chemical which can be used against ants, bed bugs, and moths if they inhabit some secluded places. The main perk of such aerosol regulators as Gentrol Insect Growth Regulator is their ability to penetrate the insects’ dens. Have you ever seen hundreds of ants flowing from a tiny crack in the wall or lots of small bugs crawling out of under the carpet at night? You can simply spray the entrance to their lair with this aerosol and your job there will be done. The complicated chemical compound will instantly sterilize the insects. Adult species won’t die, but will instead contaminate the entire nest and thus slow down the breeding substantially. It will work the same way with the drain flies.

This drain fly killer costs ~$17.4. When sprayed, it congeals as a light foam which fills up the space like a construction foam does. You’ll be able to rinse it off later easily and use your drain regularly. Not only does Gentrol sterilize the females, but it also freezes the larvae thus preventing the growing moths to hatch.

The Amazon rating of this product is very high, it’s 4.1 stars. Why so? Well, Joe thanks this product for complete extermination of flies and a long period of action, and Kristine calls it “the best season product” against the insects. All of the complaints there have something to do with exterminating other insects, such as water bugs, which are often confused with cockroaches. It turns out that this aerosol works effectively with the subject of our article, after all.

Price: ~$17.4 Check the current price

Sewer Flies FAQ

What factors increase the probability of these flies appearing at my place?

Drain flies love warmth. The official website of the NYC Department of medicine and mental health states that they breed in summer when the temperature is very hot. Easy access to food also stimulates their breeding.

Do drain flies bite?

No, they don’t need blood for breeding, and they don’t feed on living flesh either. They have neither the sting nor the mandibles.

Will using the traps and poisons only be effective for eliminating the drain flies completely?

Theoretically, if you’ll consistently kill adult species, they might stop reproducing in winter only if the temperature at your house will be as cold as the temperature outside. That’s why this is not really an option, you still have to eliminate the “nest” of the moths.

I poured anything I could into the sink (maybe except for the burning gasoline), and the flies are still intact. How come?

If cleaning the sink didn’t help, then you’re dealing with the fruit flies. You have to use other products to eliminate them since they live outside the sink (in your kitchen probably feasting on fruit and sweets). They may circle anywhere though when looking for food.

Drain Fly Killers Comparison Chart




Brief description


Brushtech super flexible drain brush: photo Brushtech Super Flexible Drain Brush Flexible drain brush

Removes clogs and debris from drains


Invade Bio Drain Gel 1 quart: photo

Invade Bio Drain Gel


A very economical product with a nice smell which eliminates drain flies only

~$13.18 for 1 qt

RID X Septic Treatment min: photo RID-X Septic Treatment Gelpacs Natural bacteria and advanced enzymes for septic tank treatment


Invade Hot Spot Bio Foam: photo Invade Hot Spot Bio Foam Foam This bio foam is the good choice for getting rid of drain flies in hard to reach wet areas where you can't apply gel.


drain gel min: photo

Drain Gel


An analog of Invade Bio Drain Gel which costs less per gallon

~$14.96 for 1 qt

Gentrol Insect Growth Regulator: photo

Gentrol Insect Growth Regulator (IGR)


A versatile growth regulator, which slows the insectsbreeding process


Why Are Sewer Flies Dangerous?

  1. They infest you through food. Drain flies love landing on your sandwiches or jam, especially if your counter is right next to the sink. Their legs carry infection which they pick up near anything decomposing. This infection may range from dirt to some extremely dangerous bacteria.
  2. Sewer flies which live in the bathroom are dangerous for children. You can’t bathe a child near the drain flies hotbed as they can accidentally get in a child’s eye or mouth… Moths are dangerous neighbours for kids anyways.
  3. Drain flies bring along their friends. Sewer flies and their offspring are also a breeding ground… for larger insects. Following the drain flies, you find some spiders, larger flies, and other bugs in your house.
  4. Allergies. Of course, sewer flies are not as allergenic as bees or wasps, but there are known cases of acute allergies caused by the drain flies. The official web-site of the NYC Department of medicine and mental health even warns that these flies are dangerous for those who suffer the most severe allergies – you have to get rid of drain flies fast!

Conclusion: When fighting the sewer flies, you will hardly do only with the drain gels and aerosols. You need to do some hard physical work: you have to clean the sink and other drains well. If you’re not so confident you can do it, consult a specialist. Any plumber or a utility serviceman can cope with this task. On the other hand, once you eliminate the sewer flies yourself, you’ll gain a true life skill. We hope that our review helped you understand which product will be most useful for your drain fly infestation.