How to Get Rid of Drain Flies | Proven Techniques for Fast Results!

Written by George Climer | checkbox Reviewed by Articles on Pest Samurai undergo a rigorous evaluation process by our Science Editors. Each article is scrutinized prior to publication and upon significant updates. Learn more about Pest Samurai Editorial Process. Steve Vanatta

Nobody wants to deal with bug problems, but some, like ants, flies, and mosquitos, seem to come with the territory. But flies coming out of a kitchen sink? Do they really live there, and if so, how can you get rid of drain flies?

How to get rid of drain flies? To get rid of drain flies, you need to locate where they live and remove the dirty water or sludge they feed on. Infected drain pipes need to be cleaned, including the traps. If cleaning your water pipes doesn’t get rid of them, they’ve found other sources of water that need to be eliminated. 

If you have a drain fly problem, keep reading. In this article, you’ll learn why they’re in your house and the best ways to get rid of them.

What Are Drain Flies?

What Are Drain Flies

Drain flies, also known as moth flies, filter flies, or sewage gnats, are aquatic flies that feed on the organic matter they find in drain pipes. They reproduce in polluted water or wet organic soils, feeding on decaying organic materials. Inside a house, they can be found in plumbing fixtures, garbage disposals, and drain traps.  

Drain flies can also be found outdoors, especially near dripping pipes. Sewage treatment plants are a favorite home of theirs. 

Even though drain fly is small, they’re poor fliers and stay close to where they’re born. They also prefer to fly late afternoon or at night, when they’re less likely to be spotted.

What Do Drain Flies Look Like?

What Do Drain Flies Look Like

Drain flies are small – less than 1/4 in (6.35 mm) long. It would take four of them to cover your thumbnail.  

They have broad bodies and short, thick hair on their backs, giving them a fuzzy or mottled appearance. Their dark wings are covered with scales, an evolutionary trait that creates a cloud of smoke when they’re swatted, letting them escape.

Types of Drain Flies

Three types of small flies can live in or near drains, and some refer to any small fly that breeds or feeds in drains as a “drain fly.”

These are the most common types of flies found in the home.

  • Fruit fly: If the fly coming out of your drain has red eyes, it’s a fruit fly (family Drosophilidae) that has been feeding on rotting food in your drain. 
  • Phorid flies: Phorid flies (family Phoridae) feed on decaying organic material, including rotting carcasses (which is why they’re sometimes called “coffin flies”). They’re more commonly known as “scuttle flies,” as they scuttle across surfaces. They’re rarely found in homes (although they can be pests near mortuaries) and can be easily identified by their arched thoraxes, which give them a humpback appearance.
  • Moth flies: The third type of fly that lives in pipes is also known as moth flies (family Psychodidae) due to their appearance.  

Where Do Drain Flies Come From?

Contrary to what some people say, drain pipes don’t come up through drains. Instead, once they smell a good breeding ground, like a clogged drain, they enter your home through small holes, such as torn screens or small gaps around doors.

How Long Do Drain Flies Live?

How Long Do Drain Flies Live

Drain flies live between 21 to 27 days, but temperatures in the mid-80s and above shorten it. Drain fly eggs hatch within two days, and the white or creamy brown drain fly larvae live for 8 to 11 days.

In the pupae stage, the larvae darken to yellow or brown. Within two days, adult drain flies emerge. Males live for a few days, and females survive up to a week, during which time they lay eggs, usually somewhere between 15 to 40.

When temperatures are under 46°F (7.78°C), larvae don’t reach the pupae stage, which is why it’s rare to see drain flies in the winter.

What Do Drain Flies Eat?

Drain flies eat decaying organic matter, flower nectar, microorganisms, and algae in the water while in their natural habitat. At sewage plants, the larvae help purify the sewage water by feeding on the organic material caught in sewage sludge. Wind can carry them for a mile or more.

In homes, drain flies live and eat the organic materials in dirty water. A typical food source is a sludge found in pipes, especially traps. However, they don’t limit themselves to pipes – any location where damp water with organic material is located will do. 

Are Drain Flies Harmful?

Are Drain Flies Harmful

Drain flies are generally not harmful. In most cases, they’re considered nuisance pests, especially if they begin to appear in your house. No one wants to have small flies hovering around windows, lights, or bathtubs. 

They have a short life cycle, so the chance of them transmitting a dangerous disease is slight. Although there’s a possibility they could do so in the future, no one has documented an instance where they’ve done so.  

In rare cases, large infestations can lead to respiratory problems from breathing in the fine scales that fall from their bodies.

But those situations are rare. Most of the time, drain flies aren’t dangerous, but they sure can be annoying. 

Do Drain Flies Bite?

Drain flies don’t bite. The mouthparts of a drain fly are too small. They also have no reason to bite since they don’t feed on blood. However, small biting midges also called “no-see-ums” or “sand flies,” need a blood meal for their eggs to develop. They’ll occasionally breed in indoor potted plants but are more likely to live outdoors.

Is Drain Flies a Danger to Our Health?

Although controlling drain flies is important, they’re not directly a danger to our health. However, a drain fly infestation could signal harmful conditions.

For example, the moisture in the walls of a house or a basement they live in can become a breeding ground for mold, which could be a significant health concern.

Their presence could also indicate that there’s a water leak in the pipes, and the water could cause structural damage if not located and repaired.

What Causes Drain Flies?

What Causes Drain Flies

Drain flies are caused by the state of your drains. If you don’t regularly clean them and do not get rid of stagnant water that can typically get stuck in your pipes and drainage areas, you’ll attract drain flies.

What Attracts Drain Flies?

Drain flies are attracted to the sludge and other organic matter in your drains. They like stagnant water and will attach themselves and even bury themselves to the sludge, which is why they aren’t simply swept away when you run water.

The drain flies lay their eggs in the sludge. When the eggs hatch, the larvae feed on the organic matter in the sludge until they turn into adults. They will emerge from the drain, hang out on walls, lights, or windows and then return to the drains at night.

How Do You Get Rid of Drain Flies? Step-by-Step Instructions

How Do You Get Rid of Drain Flies Step by Step Instructions

You can get rid of drain flies by eliminating their breeding areas. To do that, you need to determine where the flies are coming from, which will be locations with moisture that have organic debris. In homes, drainpipes are a favorite, as slow-moving or clogged-up drains are ideal food sources.  

If you see them coming out of a drain, you need to clean that specific drain pipe. But if you’re unsure in which sink the drain flies live, you need to cover up sink drains at night when they’re more likely to come out. You can do the following:

  • Tape a plastic bag over the drain.
  • Smear Vaseline in a clear plastic cup and set it over the drain.
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Leave overnight. If drain flies are present, you’ve found their source.

How Do I Get Rid of Drain Flies in Specific Places?

You can get rid of drain files in specific places by first locating where they’re laying their eggs. You can then use techniques specific to that location.

Remember, you can kill adult drain flies with a flyswatter, a spray, or a trap, but you’ll continue to have problems if you don’t kill the eggs. 

How To Get Rid of Drain Flies in My House?

To get rid of drain flies in your house, the first step is to find out where they’re laying their eggs. Since drain flies aren’t good flies, when you want to get rid of them in your house, potential problem areas are usually going to be in the vicinity of the fruit flies.

If the infestation is in your bathroom, you probably won’t see them in the kitchen. 

Related: How To Get Rid of House Flies? | Effective Techniques

How To Get Rid of Drain Flies in Bathroom?

How To Get Rid of Drain Flies in Bathroom

Drain flies in bathrooms typically live inside sink or bathtub drain pipes or in a toilet tank. Cleaning toilet tanks and sink drains is easy, but bathtub drain pipes cannot be easily accessed.  

To get rid of drain flies in the bathroom, you have several options:

  • Clean the inside of the drain with a pipe brush and your usual cleaner. Afterward, pour boiling water down the drain.
  • Combine ½ cup salt and ½ cup baking soda with 1 cup vinegar and pour the mixture down the drain. In the morning, pour boiling water down the drain.
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  • Use an enzyme cleaner or Bio-Clean Drain Septic to clean out the bathtub drain. Products that contain natural bacteria will also help keep your septic tank clean.
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  • Trap them with an apple cider vinegar trap. Fill a small dish, cover it with plastic wrap, and poke some holes in the plastic wrap. The apple cider will lure the flies, and the wrap will trap them.

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How To Get Rid of Drain Flies in Garbage Disposal?

If your garbage disposal is dirty, drain flies will be attracted to it. So you need to clean out the gunk thoroughly before you take the unit apart. 

To get rid of drain flies in your garbage disposal, do the following:

1. Fill your disposal with ice cubes.

2. Add a cup of vinegar and turn it on.

3. Let it run for 30 seconds.

4. Add some dish soap and a slice or two of lemon to get rid of additional grease. 

5. Let half a cup of baking soda and a cup of white or apple cider vinegar bubble get good and bubbly before you run the disposal.

If the flies reappear, then use an enzyme cleaner or Bio-Clean.

How To Get Rid of Drain Flies in Aquarium?

How To Get Rid of Drain Flies in Aquarium

If you have drain flies in your fish tank, they may have found enough organic matter in your tank to feed off. Here are some places to check:

  • Inside the lid; clean it thoroughly before replacing it.
  • Under the substrate.  
  • Near the filter.

If you clean around those areas and the flies are still present, the best solution is to drain the tank and let it dry out. 

How To Get Rid of Drain Flies in Sump Pump?

Automatic sump pumps trigger when the water reaches a certain level. Sometimes the small amount of remaining water can attract fruit flies.

To get rid of drain flies in a sump pump, you’ll need a scraping tool, a large bucket, a garden hose, and a shop vac. Then, do the following steps:

1. Make sure the power to the pump is off.

2. Turn off any water that leads to the pump.

3. Remove the pump from the pit and clean it. Rinse it off with a garden hose and then scrape off anything that is caked on the pump. Give it a final rinse when you’re finished.

4. Don’t forget to drain the check valve in the sump pit.

5. Use the shop vac to vacuum up water in the sump pit so your clean pump doesn’t go back into a wet and dirty pit.

6. Reconnect the pump.

How To Get Rid of Drain Flies Outside?

How To Get Rid of Drain Flies Outside

Since drain flies don’t fly far, your primary concern is to keep them from building nests close to your house.  

Standing water close to your house is a potential breeding ground, and you should build up that area with dirt or consider installing French drains. Rain barrels and tree holes are other locations they breed in. Another common site is near the air condensation lines, especially those located in a shady area.

Damaged septic tank lines can also be a source of drain flies. Unfortunately, even if your septic system isn’t compromised, if a neighbor’s is, wind can carry them to your yard. For this reason, you should check openings around your house for spaces they can enter, and seal any gaps you can find. 

How To Get Rid of Drain Flies in Kitchen Drain?

How To Get Rid of Drain Flies in Kitchen Drain

The kitchen drain is one of the most common problems areas homeowners have to deal with. If any drains are clogged or draining slowly, unclog them. Use a plunger or snake to loosen the clogged material and remove as much as you can. Don’t rely on a drain cleaner as it won’t kill off all the drain flies.

To get rid of drain flies in a kitchen drain, follow these steps:

1. Run hot water to help clean out the drain.

2. Remove the drain trap and clean it out thoroughly and then replace it.

3. Pour an enzyme cleaner such as Green Gobbler Enzyme Drain Cleaner into the drain. Because they leave a chemical layer on the pipes, enzyme cleaners do a better job of keeping the pipes clean.

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Avoid using bleach because it’ll kill some but not all drain flies. Also, it won’t get rid of the gunk they feed on.

How To Get Rid of Drain Flies in Basement?

To get rid of drain flies in a basement, find the source of water. Perhaps you have a leaky drain pipe, cracks in the floor, or they’re entering through pipes that haven’t been caulked. Due to their short lifespan, once you remove the water source they breed in, they should be dead within two weeks.

Drain flies that have taken up residence in your crawl space might continue to live there for months, as long as they have access to moist soil. In that case, installing a moisture barrier is a far cheaper option than removing and replacing the soil.

How To Get Rid of Drain Flies in a Restaurant?

How To Get Rid of Drain Flies in a Restaurant

Although drain flies are nuisance pests, diners still don’t want to see tiny flies while eating. So getting rid of them is essential for a restaurant’s reputation.  

To get rid of drain flies in a restaurant, you need to first identify the source. In kitchens, it’ll often be a drain that isn’t cleaned often. Remember, simply pouring vinegar and baking soda solution down the drain won’t be enough to clean off the gunk the drain flies live in. 

You may need to use a pipe brush or snake to thoroughly clean the sides of the drain. If you choose to use a drain solution, make sure your local health department says it’s okay to use. Once you’ve removed the infestation, add cleaning the drain to your biweekly cleaning checklist or routine.

How To Get Rid of Drain Flies in Plants?

If drain flies hover near house plants, then they’ve most likely established larval nests in the moist soil. 

To get rid of drain flies in plants, the right solution depends on whether your plants can go for two weeks without being watered. If they need frequent watering, apply Biologic’s Scanmask Steinernema Feltiae, which can control a variety of pests. 

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A second inoculation will be required to eliminate the pests.

What To Use To Get Rid of Drain Flies?

Sometimes cleaning a drain thoroughly enough to kill off drain flies isn’t possible. In that case, you have other options to get rid of them – traps, sprays, and insecticides.  

However, it won’t solve the long-term problem because they kill the adults, not the larvae.  

Best Drain Fly Traps

Sticky traps will catch some fruit flies, but they’re unsightly.

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A better option is a fruit fly lure. The Eco Defense Fruit Fly Lure kills on contact, is non-toxic and lures fruit flies and drain flies. Pour the solution into a small dish near where the flies gather and wait. When the dish is full of flies, pour it down the drain.

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Best Drain Fly Sprays

If you want to use a spray, any insect spray will kill drain flies. However, many people would prefer less toxic pest control sprays inside the house. Wondercide Indoor Pest Control contains non-toxic ingredients such as sodium lauryl sulfate, cedarwood oil, and lemongrass oil to kill drain flies.

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Aerosol sprays that contain pyrethrin, such as Garden Safe Insect Killer, will also kill drain flies.

Best Insecticides for Drain Flies

The best way to get rid of drain flies is to kill them where they live – in your drain. Covington Drain Fly Repellent eliminates and prevents infestations by coating the pipes with a thick gel that repels the flies. It can be used in the home as well as in restaurants and bars.

How To Get Rid of Drain Flies Naturally?

To get rid of drain flies naturally, let bacteria eat up the drain flies’ food source. Kinzua Fly-Zyme is one such product. Pour it down the drain and the non-pathogenic, salmonella-free bacteria reproduce rapidly, feeding on the organic matter in the pipes. It’s safe for use at home and in commercial kitchens. 

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Home Remedies for Drain Flies

Although there are plenty of home remedies on the internet, for every person who says they work, you can find someone who says they don’t. Still, since they aren’t toxic, inexpensive, and use ingredients commonly found in kitchens, they could be worth a try.

Here’s one such method:

1. Pour apple cider vinegar into a glass.

2. Cover the glass with plastic wrap that you’ve poked some holes in.

3. Place the glass near the area where you see the flies.

The vinegar will attract the drain flies, and they’ll work their way into the glass and drown.  

Another common recipe is to use a solution of equal parts sugar, water, and white vinegar to which you add a few drops of dish soap. Place the bowl containing the solution near the sink. If the drain flies are attracted to the liquid, they’ll fly into the bowl and drown.

Related: What Repels Deer Flies | 7 Best Deer Fly Repellents

List of Sources

Townsend, L. (2007). Drain Flies or Moth Flies. University of Kentucky.
Waldvogel, M., Alder, P. (2018). Drain Flies. NC State Extension Publications.
Klass, C. (1978). Drain-Flies. Cornell University.
Michigan State University. Moth flies or Drain flies.