How to Get Rid of Drain Flies

Drain flies, or sewer gnats, are tiny insects of rusty and black colors that get into houses through basements and windows. They prefer to breed in moist places filled with rotting organics; kitchen sinks and bathroom drains are just perfect for them, pipes there tend to get clogged with food leftovers or organic components of human bodies. When the environment is suitable, the reproductive cycle of drain flies can take just a week, so they can become a real headache if neglected.

It is essential to know how to kill drain flies naturally, as this may help in eliminating the infestation at its early stages. Here are some hints.

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How to kill drain flies naturally

#1 Physically remove the adults

A slipper can be a cruel drain fly killing device. You will have to hunt the flies down, which is not that hard, taking into consideration that they (ironically) hardly can fly and jump from surface to surface instead.

While being a good exercise, it is a partial remedy, for adults are only one side of this issue — they are going to be replaced by their larvae.

#2 Block the drain with a duct tape

This method is used both for the identification of an infestation and in combating it. Place some duct tape over the drain (or drains) in a room where moth flies are present and check for dead flies on another side after a while. If there are any, you have probably found their breeding spot! Block it with duct tape repeatedly to kill a bunch of flies now and then; it works particularly well when placed in the night, as sewer gnats are active during this time.

#3 It’s time for pipe cleaning!

Yet another way to get rid of drain flies naturally is cleaning the pipes, denying the flies an opportunity to feed and breed. Find a brush: the longer it is, the better, and remove the clogs of organic material that got stuck within the pipes. A flexible drain cleaner would be an even better option, for they are usually longer and, therefore, can reach farther. Ideally, gnats will have no place to lay eggs after you have done and will die off in a couple of weeks.

Bio Drain Drain Fly Killer

#4 Check the U-trap

U-trap is located underneath sinks and drains — it is used to prevent sewer gases from entering the living quarters. As useful as they are, though, U-traps are perfectly fit to be infested by drain flies because of their crooked shape. Make sure to take it apart and check for any organic debris that could be used as breeding grounds.

#5 Bleach and boiling water

This method is more effective when combined with pipe maintenance. Pour diluted bleach or boiling water down the drain to ensure that no bacteria remain on the pipe edges — drain fly larvae feed on them. Repeat the procedure for at least a week: larvae of some gnats anchor themselves to pipe edges with special body parts, which makes them quite hard to wash away. Not overdo, though: bleach may cause damage to plumbing.

#6 Apple cider vinegar trap

Some insects are attracted to apple cider vinegar as if it was a lighting bulb in the middle of the night. Use it to your advantage in pest management: mix vinegar with soap or dish detergent in a bowl, and place it near the infested sites. Lured by the fermentation odor, drain flies will come closer and get caught in the liquid. The main advantage of is method is that it is applicable not only for drain flies but for fruit flies and insects in general.

#7 Fruit trap

Sewer gnats are feeding off decomposing organics, which is one more opportunity to set a deadly trap for them. Cover some fruits with food wrap and make holes of the respective size (around 5-6 mm) in it — the pests will fly inside, attracted by the smell, and will not be able to get out. This approach to drain fly elimination is similar to the preceding one, but it is more effective in the case of fruit fly infestation and should be considered as an additional way to get rid of drain flies naturally.

#8 Light trap

Drain flies are often called moth flies. They share with moths not only general fuzzy appearance but the character trait of being attracted by bright lights as well. Lure them with something bright! You can, for instance, place a bowl of water below the light source, so they drown themselves.

#9 Surround your house with plants that drain flies hate

Cloves, lavender, basil, and mint can help in combating the drain flies because they are repelling the pests with their strong smells. Place the plant (or all of them at once) in each room of your house and watch the drain flies disappear! It is the most natural way to get rid of drain flies, as nature is involved in a literal sense.

Beware: make sure that you do not hate the smell of these plants as much as drain flies do.

#10 The power of acid-base reactions at your fingertips

Prepare your drain by firstly pouring some boiling water down the pipes. Then apply baking soda with the vinegar: it is going to start a bubbling acid-base reaction. Leave the whole thing for a while, and then wash everything out again with boiling water.

While it is a helpful natural way to remove weak clogs and therefore get rid of drain flies that breed in them, you may need something stronger for more serious pipe blockages.

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What to do if natural methods do not work?

Natural methods may not suffice if the infestation is serious and drain flies keep coming back. Should that happen, there are other options to eradicate drain flies.

The first thing that comes to mind is using fly sprays, but there are some considerable shortcomings involved:

  • They cannot be used in kitchens due to their toxicity;
  • Are not suitable for households with children for the same reason;
  • The rooms where fly sprays were used cannot be used for an extended period.

InVade bio drain gel

This is where drain gel cleaners may come in handy. Unlike sprays, they are non-toxic and are designed specifically for use in the kitchen. Drain gels use either enzymes or bacteria that eat through the organic matter in the pipes, depriving drain flies of breeding sources.

Click here to buy InVade bio drain gel on Amazon!

InVade Gel does not contain potent chemicals that may be harmful to humans. Hence, it can be used to unclog not only kitchen sinks, but shower drains as well because there is no risk that hazardous chemicals will evaporate and be inhaled.

When poured down the drain, InVade Bio Drain Gel uses a combination of thick citrus oil and microorganisms to clean out the pipes and drain fly breeding sites.

Apart from getting in touch with a professional pest control service, this is probably the most powerful solution to the drain fly problem.

Invade Bio Drain for drain flies reviews

The Invade Bio Drain for Drain Flies product has many reviews on Amazon and other e-commerce sites. We checked what people told about Invade Bio Drain products:

*Please be advised that these reviews are independent user reviews and not related to Always read the instructions of Invade Bio Drain and use the product accordingly.


Our family faced a terrible drain fly infestation not so long ago. These gnats were simply everywhere, it was impossible to even read in the bedroom, as flies come in there too and distracted me from the process.

I haven’t seen them before and thought that I can just crush them on the spot to get rid of them. My walls are covered in black flecks from swatted flies up until now. It was of no use.

Then I’ve done some research and ordered a gallon of BioDrain, poured it in all of the drains in our house for 4 days. And we have NO DRAIN FLIES anymore now. I’m totally keeping it in case these horrid pests are coming back, and I am genuinely happy that such a thing exists.

By the way, during my research, I’ve seen that some forum users got their plumbing removed and reinstalled at tremendously high prices. Too bad it’s too late to tell them about BioDrain.


We were so happy to move into our new apartment, but after the first three months, drain flies came out of the blue and ruined the fun. My children liked them, called them little moths, but I was extremely annoyed.

All home remedies went into action and proved useless, including drain cleaners. I was worried so much that my children can get their hands on these chemicals! And it didn’t help, too.

Then I’ve discovered this product and WOW IT WORKS. I was a little bit skeptical about it because it doesn’t smell like it can kill an adult elephant, and I believed that it must reek of harsh chemicals to be any good.

I applied it to drains for three days, and now I do prophylactics every now and then. Not a single drain fly ever since! What a great product!


I am familiar with sewer flies, so I’ve started to kill them as soon as I’ve noticed them. They are poor fliers and that is not that hard to do. Then I used this cleaner so they do not breed. Pouring it before bedtime is the absolute best option because it stays in pipes for a long period.

Bio Drain Drain Fly Killer


It was the only way to solve the drain fly problem for us, as all other methods haven’t really worked. It took just a couple of days for us to get free of the pests, granted that we followed the instruction carefully.

Our infestation was awfully grave, we hired different plumbers twice and got no results whatsoever. And then Bio Drain got things sorted out in about a week. I am going to use it as a preventive measure against drain flies, I use it regularly (at least once per month), so they do not reappear.


A wonderful product. I tried everything, including various sprays and flypaper. Nothing helped. Then I’ve decided to give Biodrain a try, and the flies vanished in a week. Just remember to treat all the drains and leave it for the night. It’s non-toxic.


The effect was amazing. After just a week we’ve spotted that there are significantly fewer gnats. We poured the product down our kitchen and bathtub drains, wash machine drain and bathtub were also treated. Initially, there were up to 20 flies at once in the laundry room and bathroom, and that number shrunk by half.

After reusing it next week, I’ve spotted only TWO flies in total. We are going to apply it once more and hope that they will completely disappear.


Fruit flies are gone in a week and my drains are functioning much better as well. The citrus smell is very pleasant and sweet.


I found out that little flies appear near the drain I rarely use. Now I periodically clean it with the product and no flies bother me. All it took was two-three applications, and the problem’s gone. Going to make cleaning the drains regularly with BioDrain my monthly habit.


We’ve bought a house with a septic system and got acquainted to these “sewer flies”. It was disturbing, and we had no idea what to do, read the reviews and decided to give this thing a try, even though the reviews were mixed. A month has passed since then, and we haven’t seen a single fly. One application sufficed to get rid of them.


Great job on dealing with an infestation of a drain on the second floor! We haven’t had the same issue on the first floor and wondered how to deal with it. The flies were gone after a couple of usages, and the smell is outrightly amazing.


AWESOME stuff! We have thought that we will never get rid of drain flies. The rear part of our house, where the bathrooms are, was full of them. It was so frustrating that I tried to eradicate them, using home remedies I’ve found on the web, but it didn’t help. I was desperate and ready to give in, and finally, I’ve discovered this.

Firstly I’ve used it every day, then once a week, and now only once a month. As soon as a see a drain fly, I use it again, not leaving it a chance to come back. The only issue was one of my metal drains turning orange, but it washed out in two days. Other drains, despite also being metallic, have not been colored. Pour it carefully and follow the instruction. It’s safe, no harsh chemicals in it. Smells of oranges. Highly recommended.


Annoying tiny gnats in my drains were not pleased when I used it on them. I’ve never heard of sewer gnats before I’ve got them. I just went to my kitchen and saw a lot of these creatures, filthy insects, flying all around the place. The trash was taken out, I wiped every surface I can get my hands on, and yet they didn’t go anywhere.

I’ve contacted pest control and got a consultation, they were the first to tell me these are drain flies. Bleach, Drano, boiling water — nothing seemed to really help. I even got my hands dirty, cleaning the pipes and extracting a fair amount of goo out from pipes.

Even though I have killed a lot of flies, and that I put my best efforts to clean the pipes, sewer gnats would simply not go away. Quick research showed that they cling to the pipe edges so it is hard to get rid of their eggs entirely.

I was looking for a solution, talking to people which have had the same issue, and finally this brought me to BioDrain. I’ve decided to buy just a little bit to give it a try. It worked, so I bought more. Now I buy it regularly because of the never-ending nature of my fight against sewer gnats. They keep coming from year to year.


I was impressed by the reviews of the product and the prices were fine, so I bought it and gave it a chance. I followed the instructions strictly, my drains were treated with the product every other day before I went to bed. I had the idea that boiling water may help the process, too.

And eventually, there are no drain flies in my home anymore. I know that they are harmless, but I just couldn’t stand these furry annoying insects. I wanted them gone. BioDrain gave me what I wanted without any serious chemicals involved, and the smell was pleasant. Guess I just have to continue using it from time to time, preventing the collection of trash inside the pipes. The drain flies can return otherwise.

Bio Drain Drain Fly Killer


This product is a lifesaver! I couldn’t do anything with my drain fly outbreak, it was just HORRIBLE. Baking soda with vinegar and two exterminators handled only about 90% of the issue but I still noticed some flies, and I really disliked that.

I managed to get rid of them only with BioDrain!! …And it took me only a week to do so !! Gonna use it on a regular basis to keep my sinks bug-free and fresh, as the gel has a pleasant citrus smell. Thank you BioDrain!!


The price is quite important for me, so I was frightened that I will simply throw the money away. Well, now I know that the product is worth every cent.

It was delivered to me on Sunday, I’ve been using it for the two following days. Only one fly spotted since then. We’ve got a lot of fruits, and vegetables, and plants at home, so I thought that these were fruit flies, but soon they got bigger…

I’ve read about flies online, a lot. There were flies in the bathroom now, and I found it utterly strange. When I’ve figured out that these are drain flies, the situation was already pretty grave: they were crawling in sinks, flying around in dozens, accumulation anywhere near moisture. It was like I’m never going to be able to do anything, the game’s lost.

IN ONE NIGHT ALL THE PESTS DISAPPEARED, WHAT A RELIEF. Just got the products in the pipes, following the instruction, spilled a bit around the drain circle. No more flies to irritate me. Thanks!


I had some troubles in the beginning, as drain flies seemed to breed somewhat deeper than usual, but then I found them. Had to partially remove my pipes to find their spots — these were in the U-trap and past it. So, what worked for me was a flexible tube that I used as a way to get the biological drain cleaner for phorid flies everywhere and ensure that no surfaces within the pipes remain untreated. Just pouring it down the drain would not help in my case.

I’ve done this three to four times and flies died off. It works.


Used this to get fruit fly eggs killed in my kitchen drain. Boiling water was of no use, so I decided to come back to InVade BioDrain once more.

Used it twice and the flies vanished. I have no idea how this is possible, but it is truly amazing and very convenient. I combine it with hot water, using BioDrain after I’ve poured some down the drain, and then I add one 1/2 cup of BioDrain, too. Then no more water for six hours or so. It’s better to not use the drain at all for this time for the bio gel to do its job.

After a week of worries, I can breathe easier at last — my fruit flies are gone.


We got rid of these flying bugs that came from our shower, finally! Had to leave BioDrain for four nights in a row to achieve that. BUT THE BUGS ARE NO MORE BOTHERING US!!! We’ve been struggling to get rid of them for a month and had to treat it longer than people usually report, but at last, no insects are left in the bathroom.

Now we use the product as a precautionary measure once a week, just to make sure this nightmare never happens again. I was questioning whether the product is efficient or not, thought it is overpriced, but at the end of the day it works, smells nice, and doesn’t contain any harsh chemicals. Could only recommend it.


I did my best to free my house from sewer flies tried each and every method out there but nothing was particularly effective. Then I used bio clean for drain flies and in a couple of days I could see the results, there are no flies anymore, a really good product. There’s still more than half of the gel left in the bottle. It’s great to have around just in case.


Is effective if the directions are followed. I had a drain fly problem, fought it for 3-4 days, and then the flies went away. Didn’t use this thing after that and no flies have returned nonetheless.


Got half a cup in each of my drains and left it for weekends, then came back to discover that my drains are clean and no pests are longer occupying them. Ten days have passed since then and I haven’t seen a single fly. Great job.


We had to kill hundreds of flies per night two weeks ago — and no we have none of them. We used the product after treating all drains in the house with boiling water and leave it for an hour. It’s important not to just pour it down, but to get it on the edges, as edges are usually where the filth is aggregated.

We also had an overflowed drain that as we can see it was a huge problem: drain flies love moisture and trash, and that drain was basically moist trash. Had to be doubly cautious with that one.

Others have mentioned that the orange substance can leave stains on fiberglass, so we were worried. It went ok, just make sure to clean it and be careful when pouring.

We couldn’t be happier with the purchase. It works, it smells nice, it’s ok to spill some on your hand. The price was not small, yes, but we are going to order more and use it occasionally not to leave the flies any chances of coming back.

How to Get Rid of Drain Flies – FAQ

What home remedy will get rid of gnats?

It is possible, for example, to set a rather inventive trap: place a candle in a dish filled with water. Turn off the lights — it is time to see why drain flies are also called moth flies. The pests will either burn in the flame or fall into the dish, dooming themselves to drown. Just be sure to stay somewhere near the candle and watch the fire, do not leave it unattended!

Does fly spray kill drain flies?

Fly sprays are an effective method used to kill adult drain flies. Please remember that fly sprays are toxic: you will have to leave the room and ventilate it before returning. They are also inadvisable to use in kitchens or when the children are present. Apart from that, killing mature specimens is useless without clearing the breeding sites beforehand.

How long does it take to kill drain flies?

It is not that hard to kill drain flies — it is hard to make sure that they do not come back. The drain worms develop into adults in a few weeks and leave breeding sites. Even if you have killed all flies before, their numbers will replenish. Bleach and boiling water can kill some larvae, but specialized equipment (i. e. biocide drain cleaners) is required to ensure complete pest extermination. But in general, it needs at lest 2-3 weeks to kinn drain flies, if you are lucky.

Does cold weather kill drain flies?

It may be tempting to wait out the infestation in the hope that drain flies will die off because of the cold. It is true: these pests die out in winter and thrive in summer, but this applies to the full extent only to those flies that live outdoors.
If they manage to get into a house, they can go on breeding even during winter frosts, though cold temperatures damage their liveliness. So they will persist, bursting in their numbers during the summer and shrinking during the winter. Read more: Life cycle of drain flies

Can an exterminator get rid of drain flies?

When it comes to pest control, qualified professionals are the best option available, always. Considering how resilient drain flies are, making sure that the household is free of them is demanding for a non-professional. There are some ways to battle against the pests on your own, but who can guarantee that it will be enough? On the other hand, exterminators will analyze the circumstances and formulate a plan that suits your situation the most. This scenario involves no bleach with potential damage to pipes, no toxic sprays, and minimum contact with maggots on your part. Dealing with pests is frustrating, challenging, and plain disgusting. Do not postpone and tolerate that drain flies keep coming back — settle the issues once and for all.

Will bleach kill drain flies?

To deal with drain flies you can also strike them where it hurts — directly into their breeding sites. The gnats lay eggs in the filthy goo within the pipes; the drain fly eggs then hatch into larvae, which can be partially managed with a bleach solution. Just pour some bleach down the drain, and it will kill a portion of maggots. Be careful, though: bleach may cause harm to plumbing!

How to clean drains to get rid of gnats?

Cleaning the drain openings where the pests were spotted also helps: pick a screwdriver, unfasten the bolts, and make sure that there is no organic mess in the opening hole. Thus you can at least partially deny them access to food resources.

If you have drain fly-problem then try the InVade Bio Drain gel, with microbes and citrus oil and without any hars chemicals! Click here to read more & buy!