How to Get Rid of Drain Flies: Best Ways to Eliminate Sewer Flies from Your Life

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 by the human beings when breathing. 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. 

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.

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.

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.

  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.Brushtech super flexible drain brush: photo
  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 & Hot Spot: photo

Drain Gel

drain gel: photo

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.

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 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.

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 Drain Brush

Brushtech super flexible drain brush: photo

Flexible drain brush

Removes clogs and debris from drains


Invade Bio Drain Gel

Invade Bio Drain Gel 1 quart: photo


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

~$13.18 for 1 qt

RID-X Septic Treatment

RID X Septic Treatment min: photo

Gelpacs Natural bacteria and advanced enzymes for septic tank treatment


Invade Hot Spot Bio Foam

Invade Hot Spot Bio Foam: photo

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

drain gel min: photo


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

~$14.96 for 1 qt

Gentrol (IGR)

Gentrol Insect Growth Regulator: photo


A versatile growth regulator, which slows the insectsbreeding process


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!

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.

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Leave a Reply
Jaz  •  Saturday, 25 August 2018 15:53
I first discovered i had the sewer fly problem in my bathroom when little worms were starting to pop up & going around on the shower floor when we were taking showers ... it was already too late .. 3 weeks later and i still find worms and flies . Sulfuric acid down the drain to clear any residue they supposedly feed on didn’t work.. but it did burn my drain cap... the larvae apparently survive clorine submergions... doubt they would survive acid.. my problem must be elsewhere
Ally  •  Wednesday, 08 August 2018 20:25
I live in a 5th Wheel Rv and the drain flies are driving me crazy the past week! I've been told NOT to use any chemicals in the black tank other than what is recommended for RV tanks & sewer pipes. I've seen them fly out of the toilet drain when its being flushed. Once on the loose they seem to head directly to the humans. Those little pests can live through flying insect spray without a single one dropping dead. What do you advise for RVs? Thank you for the help!
Evan  •  Wednesday, 06 June 2018 21:11

This situation: yesterday, after returning late at night with my girlfriend from a walk, noticed in the kitchen in the sink some midge, I climbed to Google, and as it turned out, it's drain gnats. It was unpleasant to find these pests in my house, I thought this would not happen to me. I turn to the main question, what do you advise, gentlemen's? It is desirable that something is safe for humans.

Lui  •  Friday, 25 May 2018 20:05
For a very long time I studied what would really help get rid of drain flies. According to reviews I chose Invade Bio Drain Gel. And I did not expect this effect, thought people exaggerate. But this gel helped me after the first application! I recommend keeping pets away from this means.
Xano7  •  Wednesday, 06 September 2017 17:22

Drano kill drain fliesat once! We used it when we had plenty of moths. We were about to move! Thank god wekicked them out, or else I would’ve gone mad. What I liked about this product was its quick effect. It’s really worth it! I would also try combining several products and check to see what effect a mixture will give.

Kate Liesman  •  Thursday, 17 August 2017 20:11

Is there anything other than gel or traps? We have wondered how to get rid of sewer flies ever since my husband discovered them. They are so nasty, ew! We’ve just got rid of ants, now this is a new problem...

Roy  •  Monday, 17 July 2017 19:47

We are infested with sewer gnats, and we found it out within a couple of days. First there were only few of them, but then there were myriads of them. We tried calling pro exterminators, they helped, but after a while these insects reappeared. So we decided to try a gel. What would you recommend? Has anyone tried anything off this list?

Savorrr  •  Friday, 28 July 2017 11:22

You can use a drain fly trap as an alternative, as it works well and doesn’t cost too much. That’s what my relatives used against insects. This does mean that the gel works any worse; it’s just there exist some alternatives.

SveriorityNN  •  Wednesday, 05 July 2017 16:33

Could you please advise whether a drain gel will damage the pipes? Do such gels contain any synthetic chemicals or are they all natural? And by the way, are they safe for human skin?

Pozxx10  •  Wednesday, 12 July 2017 12:23

No, a drain cleaner gel is absolutely safe for your skin and pipes – otherwise it wouldn’t have been so popular.For instance, Invade Bio Drain Gel is one of the most popular drain gels on Amazon and no one ever complains of any negative impact on their skin. Go ahead and use it!

Shemet  •  Thursday, 20 October 2016 21:00
How to get rid of drain flies fast? I took a one-week vacation and came back to a whole flying colony!
Quatro199802  •  Monday, 31 October 2016 17:28
I never wondered how to kill drain flies until my kid started doing dishes! Naturally, all of his unfinished food ended up in the sink. It was a nightmare as the insects appeared soon enough. I didn’t think it was hard to remove them, but boy, was I wrong! We have only been able to get rid of them completely after installing a kitchen garbage shredder.
Kussem  •  Thursday, 27 October 2016 22:23
Hey, buddy, I don’t envy you at all. I haven’t had an infestation of such a scale, but I immediately boiled all of the sinks to kill most eggs and larvae. It had a partial effect, but some sewer flies kept on flying, so I used a drain gel as well. You should also remove any dirt from the drain, it’ll be best if you disassembly and clean the pipe bend as it gets clogged most often.
RedAf  •  Tuesday, 04 October 2016 20:57
Please advise whether drain flies can appear out of nowhere.
GrandMarshal  •  Wednesday, 12 October 2016 15:19
If you see a single flying moth, there must be other drain flies. They only breed once in their life, but according to Wikipedia each fly can bear up to 100 new pests by laying eggs directly in the drain. That’s why you should get rid of them ASAP.
Oland  •  Saturday, 08 October 2016 13:14
Absolutely not. They feed on organic matter found in the drain, so even if it seems that everything is clean but sewer flies are there, it means that they have found rotting nutrition. Hair left in the bathroom or pieces of food in the sink drain can be such potential food.
Niuton  •  Thursday, 19 March 2015 17:21

I bought Drain Gel on Amazon. Before this purchase I never used something "special" to fight with flies. This gel works. I have any sewer flies in my garden. P.S: I use just a little amount of this gel and solve my problem, so I can sell "almost" full bottle of gel =) P.P.S; It was joke

GameBoy  •  Wednesday, 18 March 2015 17:12

Vasd, did you hear something about Google? I used this trap and it works. The results are very good. It isn't stink, something like apple juice. One flies trap works active about month. Of course, no one fly cannot escape from trap. Don't be afraid and buy it - cool thing!

Vasd  •  Sunday, 15 March 2015 20:59

Is anybody used BEAPCO 6-Pack Drop-Ins Fruit Fly Traps? Is it work? How long? Is it stinky for people? Could flies escape from this trap? It's all very important for me, answer please!!

Gnome  •  Friday, 13 March 2015 16:54

TERRO Fruit Fly Trap T2500 save fruits plate on my table. In summer children play on the back yard and they like to eat something periodically. Fruits are useful. But usually drain flies appear after 3-4 hours and it's awful. This trap save fruits and my children from flies.