Why Do You Have Drain Flies In Your Home

If there’s any nuisance flying bug in your home that irritates you the most, it’s the drain flies.

These tiny flies appear out of nowhere inside your home. It makes you wonder where drain flies come from.

This guide will reveal why do you have drain flies inside your home. It’ll also reveal the sources of drain flies which nobody else told you. 

Not only that. You’ll also find out failproof ways to get rid of drain flies in your home and property. 

Plus, a lot more!

So, keep reading if you do not want any drain flies in your home and stop them from coming back.

What Are Drain Flies?

Why do you have drain flies

Drain flies, also known as sink flies, filter flies, sewer flies, moth flies, and sewer gnats, are tiny moth-like flies with a fuzzy appearance and brownish, blackish, or greyish.

These flies are attracted to hazardous, damp wastes that accumulate in drains, sewer pipelines, and trash bins.

An adult drain fly grows up to 0.125 inches. There are fine bristles of hair covering their wings which gives them an appearance of little moths. 

You may confuse drain flies with gnats and especially with house flies. 

But there’s one significant difference between drain flies and house flies. 

Drain flies are not strong fliers. Instead, they’ll hop from one place to another. It’s common to see them hoping from one place to another in your bathroom floor and shower grout.

In contrast, house flies can fly longer than drain flies. House doesn’t hop either.

Another difference between the two is the color and appearance. House flies are darker than drain flies, and they don’t have the moth-like appearance the drain flies have.

But the sources of drain flies, house flies, and even mosquitoes can be the same. 

What are the sources of drain flies? You’ll find out a bit later in the post.

But for now, let’s find it out why you’ve drain flies in your home.

Why Do You Have Drain Flies Inside Your Home2 Reasons Revealed

The source of drain flies is the organic debris that accumulates in stagnant water. It’s the perfect place for drain flies to breed and to eat.

That brings you to the places where there’s a possibility of stagnant water.

So, the drain flies are in your home because of two reasons –

  1. Stagnant water in and around your home and property.
  2. Clogged drains and waste in places like the kitchen, bathroom, basement, and laundry room

Let’s take a deep dive into each of these reasons. 

Stagnant Water 

Like house flies, rats, roaches, and mosquitoes drain flies also live and breed in damp filth. 

Their sources lie in places where there’s a gathering of waste, and the place is also wet and moist. 

And nothing better matches these requirements than stagnant water. 

Whether it is in the drains or your yard, stagnant water is the source of drain flies and, the worst, mosquitoes. 

Stagnant water accumulates sewage, organic wastes and develops bacteria that become a perfect breeding and feeding place for drain flies. 

Drain flies will go to these places and lay their eggs. And unless you do something about the places holding water, you won’t be able to get rid of drain flies. 

Another point to keep in mind is the drain flies’ breeding habits. Drain flies breed lightning fast. 

That’s the reason their numbers inside the home can skyrocket from a handful few to hundreds. 

Drain flies have a short lifespan of 24 days tops. But they can lay 200-300 eggs in only 48 hours. 

From the eggs to hatch to the larvae maturing into adult drain flies takes only a week. 

So, if you don’t eliminate drain flies from the source, then for sure, it’s a matter of time that their numbers go over the roof.

Stagnant water can be anywhere inside and outside your home. It can be inside your home’s drains, underneath the refrigerator, and even in your yard. 

All those places are the go-to breeding grounds for drain flies. 

Clogged Drains And Wastes

There’s a reason that drain flies have their name as drain flies. It’s because they hover and hop around the drains. 

Clogged drains are prime real estates for drain flies to live and breed. Why?

It’s because clogged drains provide drain flies with two most important things that they need to thrive – dampness and waste choking the drains. 

When water can’t pass through the drains, then the drains turn wet from inside. As drains are the carriers of dirty water, the interiors of the drains develop a thin film or layer.

That layer is the perfect place for the drain flies to lay their eggs.

And the wastes blocking the drains from inside contain organic wastes causing the pipes to develop algae.

Both the algae and wastes blocking the pipes are food for the larvae that hatch out of the drain flies’ eggs.

Most of the time, you won’t be able to see the larvae of the drain flies. It’s because they’re inside the drains. 

The only thing that you’ll see are mature drain flies coming out from the drains. It’s because the larvae of the drain fly successfully matured into adults and came out of the drains. 

Drains of the kitchen, bathroom, septic tanks, and basement deal with a lot of wastes. Those wastes clog the drains making them an ideal place to breed. 

But hang on. How on earth do these drain flies reach the clogged drains inside your home?

How do the drain flies get to figure out that the wastes are choking the drains of your kitchen, bathroom, and basement?

Well, the answer will surprise you because the major source of drain flies is not the drains. 

Drain flies come from the outdoors, especially when your house has a yard or garden full of organic debris and dampness.

Nine things in your yard are the real breeding grounds for drain flies. These are –

  1. Damp waste in your yard
  2. Dirty wet objects like mops and buckets
  3. Compost piles
  4. Catch basins
  5. Trash bins filled with garbage, especially food waste
  6. Tires with stagnant water in your yard or garden
  7. Moist and overwatered yard with potholes filled with water
  8. Clogged sewer pipelines
  9. Water from your swimming pool or pond is leaking in your yard.

Anyone or all these nine things in your home’s outdoors can harbor drain flies and many other bugs, including drain roaches, gnats, and mosquitoes. 

There’s one common thing that binds all these nine sources. It’s a damp waste. 

Damp wastes are not just an ideal place for the drain flies to breed but also to feed. 

That’s why compost piles, catch basins, and trash bins filled with garbage are the three most significant sources of drain flies. 

And when you’ve got drain flies in your yard or garden, it’s only a matter of time they’ll sneak inside your home and look for new places to lay eggs.

That’s the time when the drains of your home attract them.

And that is the reason you’ll see them hovering around on the sink’s drains in your kitchen and bathroom

So, clogged drains inside your home can be secondary sources of the drain flies in your home. The primary source lies outside of your home. 

People living in unhygienic communities have drains flies inside their homes.

It’s not only because of the clogged drains but also because there are enough sources of drain flies in their neighborhood.

Drain flies are also one of the pests that are present in unoccupied homes. 

When the home drains are clogged, drain flies will breed in those drains despite no water running through the drains.


Because dry drains develop a gelatinous film inside, which acts as an egg laying ground for the drain flies.

When the home drains are clogged, drain flies will breed in those drains despite there being no water running through the drains.

That’s why it’s quite common to see drain flies in kitchens and bathrooms unused for days, especially when the home is dirty.

These kinds of homes can also harbor bugs like roaches and bed bugs.

How Do You Find The Source Of Drain Flies?

Drain Flies

Drains are undoubtedly the source of drain flies. But they’re one of the sources of drain flies.

There wouldn’t have been drain flies in your home’s drains had there been no drain flies outside your home. 

So, before you start to treat your home’s drains for drain flies, you’d need to look out the sources of drain flies outside your home too.

The nine places mentioned in the previous section are the potential sources of drain flies.

Look for places outside your home that have organic waste building up, leaking pipes, and, most importantly, stagnant water. These places outside your home are the major sources of drain flies. 

Also, you’d need to check for larvae of drain flies in the drains. Drain flies lay their eggs in the debris that chokes the drains.

So, open the drain cover and check underneath it for drain fly larvae. The drain fly larvae look like tiny white, legless worms with black patches on their back.

If you don’t see the larvae, chances are drain flies have laid their eggs deep inside the drains.

Anything moist, dirty, and storing even a tiny amount of stagnant water can be the source of drain flies.

How To Get Rid Of Drain Flies Inside Your Home?

You can use bleach, baking soda, vinegar, and hot water to get rid of drain flies in the drains of your home. 

Fortunately, getting rid of drain flies is an easy task. And it’s not as complicated as getting rid of other types of pests.

Let’s dive in on how to use products that might be lying around in your pantry or home to get rid of drain flies.

Will Bleach Kill Drain Flies?

Yes, bleach will kill drain flies. Bleach is an effective pest killer and eliminates various pests in drains like drain flies and drain roaches.

To prepare a bleach killer mixture, all you need to do is to pour 3-5 tablespoons of bleach in hot boiling water.

Stir the mixture well, and slowly pour it inside the drains of your bathroom, kitchen, laundry room, basement, catch basins, and in any other drains.

The mixture will kill the drain flies, their eggs, and their larvae too. It’ll also unclog the drains of its wastes.

But there’s one drawback of using bleach.

Bleach is highly corrosive. Overusing will eat away the drainpipes from the inside, causing the pipes to get thin and, eventually, break.

So, it’s always a good idea to use this method sparingly and not often. 

Also, bleach can cause skin irritation. So, always wear gloves and masks while using bleach and avoid direct contact of bleach with your skin. 

Prepare A Mixture Of Baking Soda, Vinegar, Dish Soap, And Boiling Water

If you’re averse to using bleach, then you’ve got a great alternative. 

It’s a mixture of baking soda, vinegar, dish soap, and hot water.

Add three tablespoons of baking soda and a quarter of a gallon of white vinegar in one gallon of boiling water. 

Stir the mixture well. And pour it inside the drains. 

But unlike the previous mixture, this one is not an instant killer of drain flies.

You’ll need to wait overnight for the mixture to settle down inside the drains and do its work.

The next morning, flush the drains. It’ll flush out the dead bugs and drain flies from the drain.

But this mixture has a farther reach than the bleach mixture. The baking soda expands when it’s mixed with water. 

That causes it to go deep in the drains and get rid of the drain flies.

To add more punch, you can also add a few drops of dish soap to the mixture. 

If you do not plan to use the kitchen or bathroom in your home for an extended number of days, cover the drain holes with a drain stopper.

That’ll stop any drain flies hiding in the drains from coming out.

Using A Drain Cleaner To Get Rid Of Drain Flies

Drain cleaners like Drano and Bio-clean are effective in getting rid of drain flies and unclogging the drains.

But before you use them, you’ll need to flush the drains with warm water. 

Then pour the drain cleaner in the drains to eliminate the residual wastes and any potential drain flies’ larvae and eggs.

Chemical Pesticides

There are many insecticides that you can use to get rid of drain flies. 

Homeowners use them to get rid of fruit flies and gnats, but against drain flies, they’re equally effective.

Two of the best ones are Rockwell Bio Drain Gel, and Green Gobbler.

You’d need to spray these chemical pesticides on damp places with stagnant water and organic wastes.

You can also pour these chemicals into the drains with drain fly infestation.

Few Words Of Caution: Refrain from using chemical pesticides in the drains of your kitchen. These are chemicals, and if you mishandle them, they can land up in your food.

Also, read the safety instructions on the label before handling them.

How To Prevent Drain Flies And Stop The From Coming Back

Prevention is better than cure. And many homeowners will stop when they successfully get rid of drain flies.

But it doesn’t go that well. It’s because if you don’t act on the sources of drain flies, they’ll come back.

The sources of drain flies are not just breeding and hiding places for only drain flies.

Those sources are also breeding grounds for invasive bugs and pests like roaches, mosquitoes, ants, biting midges, termites, and many others.

So, the key to getting rid of drain flies lies in treating the sources of drain flies. And as you know by now, most of the sources of drain flies lie outdoors.

Here are the four steps to prevent drain flies –

#1 – Keep Your Yard Clean

A clean outdoor area of your home, which includes your yard and garden, is the key to eliminating bugs of all types.

Most yards have foliage, rotting wood pieces, and decaying mulch beds that attract bugs. To make matters worse, many people even overwater their yards and gardens.

Get rid of all the debris in your yard. 

Ensure that all the pipes and drains in your yard and near your home’s foundation are not leaking.

Leaking pipes cause an increase in dampness in the walls and yard, which attracts bugs. Water leakage around the walls and the home’s foundation makes the walls weak, causing cracks. 

Those cracks become the entry points for bugs to sneak inside your home.

Mulch beds are the go-to places for all types of bugs to hide and nest. Use the right mulch beds that repel bugs rather than ordinary wood chips.

#2 – Keep Bugs Out Of The Compost Piles

Composting is an environmentally friendly exercise, and every homeowner should do it if they’ve got the space and the time.

But as composts are decaying organic matter, it’s home to many bugs and pests. 

From roaches to drain flies, they all lay eggs and feed on the compost piles.

So, to ensure that bugs don’t take shelter in the compost piles, spray an organic plant-friendly insecticide spray on the compost piles at least twice a week.

It’ll be best if you surround the compost pile with ant and termite granules. 

Ant and termite granules sink into the soil and kill subterranean bugs that attack the compost piles underneath the soil.

But refrain from using nematodes. Nematodes are bug killers, but on compost piles, they can have the opposite effect.

Nematodes may kill the beneficial bugs and microbes that help break down the organic matter, which is essential in composting.

#3 – Fill Up The Potholes To Prevent Waterlogging

Stagnant water is the #1 reason for drain flies and mosquitoes. And you don’t want stagnant water in your yard. 

Waterlogging in potholes happens because of overwatering or after rains. Water gathers indents and holes in your yard.

Fill up those holes, preferably with sand. 

If there’s stagnant water in the soil beds and compost piles, add a few drops of kerosene in stagnant water before filling it with mud.

Kerosene breaks the film on dirty water that mosquitoes and drain flies use to lay their eggs. It causes the eggs and larvae on the water to sink in the water and die.

And if tires are lying around in your yard, get rid of them. Water collects in the tires, making it a place for drain flies and mosquitoes to breed.

#4 – Keep The Trash Bins Clean

Trash bins with wastes, especially with food wastes, also drain flies favorite. The drain flies will feed on the waste.

And the worst part is, trash bins with waste lying inside for days attract roaches, ants, and flies. 

The flies will lay their eggs too in the trash bins. That’s why you’ll see maggots in trash bins. These grubs are the larvae hatched out from the flies’ eggs.

Do not let wastes of any type sit in the trash bins for days. Dispose of the waste and keep your trash bin clean often.

It’ll be best if you spray a disinfectant or an insecticide in the trash bin after disposing of the wastes.

It’ll keep away the bugs and drain flies from the trash bins. 

Should You Hire A Plumber Or Exterminator To Get Rid Of Drain Flies?

Let’s face it. For any pest infestation that runs deep, professional help becomes necessary.

But in the case of drain flies, it becomes quite tricky. You might have to choose between a plumber and a pest controller to get rid of drain flies.

So, in what situation should you go for a plumber rather than a pest controller?

When the source of drain flies lies in the drains, and despite your best efforts, they’re coming back, you’d need a plumber.

It’s because you’d need to remove the drainpipes and get rid of the scum deposits deep in the drains to get rid of the drain flies.

Plumbers will also remove the blockages inside the drains, denying the drain flies a place to breed. 

Not to add, professional drain cleaning materials that only certified plumbers have access to will also go a long way to get rid of drain flies.

However, if the source of drain flies is outside your home and you, for some reason, haven’t been able to get rid of them from their source, then you’d need a pest control professional.

In this case, exterminators will use the right insecticides to eliminate drain flies, their eggs, and larvae.

How To Know You’ve Successfully Gotten Rid Of Drain Flies Infestation

Checking if the drain flies are gone after all your efforts is important to know if you’ve successfully gotten rid of drain flies.

There are two ways of doing it. The first is the duct tape test and the second is DIY drain fly trap.

Duct Tape Test To Check If Drain Flies Are Gone

The duct tape test is one easy way to find out. 

All you’ve to do is seal the drain holes with duct tape in the afternoon and leave it for the night.

Drain flies are active during the evening hours. If there are drain flies inside the drains, they’ll try to come out of the drain holes. 

While doing it, they’ll get stuck on the duct tape. 

Remove the duct tape in the morning to check if there are any drain flies stuck on the sticky side of the duct tape.

Continue the test for three nights. If you’re still observing drain flies in the duct tape, then you might have to hire a plumber to clean the pipes.

DIY Drain Flies Trap

Another easy way to check if drain flies are gone is the DIY drain flies trap.

All you need to do is take a bowl and pour some apple cider vinegar, sugar, water, and a few drops of dish soap in the bowl. 

Cover the bowl with a plastic wrap and create holes in wrap. 

Stir the mixture well and keep it near the drains of your shower, bathtub, bathroom, kitchen sinks, and basement sinks.

The sugary solution will attract the drain flies. The drain flies will sneak inside the bowl through the holes on the plastic wrap.

When the drain flies land in the solution, the sticky dish soap will make the drain flies stick. And the plastic wrap covering the bowl wouldn’t let them escape.

That’s also one way to find if the drain flies are gone. 

How Long Does It Take To Get Rid Of Drain Flies?

To get rid of drain flies from their sources, you’ll need at least a week of repeated treatments. 

Given these pests’ ability to lay many eggs, one or two treatments might not be enough. 

Also, you’d need to use drain cleaners to clean the drains thoroughly, which also needs multiple cleanings.

Plus, you’ll also need to check for drain flies with the duct tape method and the DIY drain flies trap to be sure that you’ve successfully eliminated drain flies in your home.


This guide answered the question of why you have drain flies in your home. There are two reasons for drain flies inside your home and property –

  1. Stagnant water in and around your home and property.
  2. Clogged drains and waste in places like the kitchen, bathroom, basement, and laundry room

There’s also a step-by-step guide to get rid of drain flies and to stop drain flies from coming back. 

This guide also clears the doubt that many homeowners have on who to hire to get rid of drain flies if the infestation runs deep – the plumber or the pest controller. 

Remember, the source of drain flies usually lie outside of your home rather than in your home’s drains. 

So, go ahead and implement these steps to solve the drain flies problem inside your home, forever!

To know more about tiny bugs in your home, check our post on tiny black bugs near windows.

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