How to get rid of drain flies

Key points

• Effective treatments to get rid of drain flies include using vinegar traps or pouring boiling water down the drain.

• Drain fly infestations often indicate plumbing issues such as leaking pipes or severe clogs.

• Drain flies are small insects that thrive in moist environments, typically near sink drains.

Drain flies have a nasty habit of turning your bathroom into their personal hangout space. These tiny insects can quickly become a nuisance in any home, leaving you wondering how to reclaim your sinks, drains and pipes.

Drain fly infestations can be eliminated with a combination of active and preventive treatments, such as setting up vinegar traps or using drain covers, and hiring pest control professionals when necessary.

When dealing with drain flies, it’s crucial to tackle the issue before it gets out of hand. We’ve enlisted the help of pest control experts to guide us through the process of getting rid of drain sink flies and restoring peace to your home.

The following information is guided by insights from Molly Keck, integrated pest management program specialist and Board Certified Entomologist at Texas A&M AgriLife Extension Service in Texas, and James Agardy, ACE, technical and training manager at Viking Pest Control in Liberty Corner, New Jersey.

How can you get rid of drain flies?

Getting rid of drain flies is entirely feasible. As a homeowner, you have several options to choose from, including the following practical methods.

Clean drains with a brush or drain cleaner

Use a metal pipe brush or commercial drain cleaner to scrub away organic matter and debris that may have built up in your kitchen or bathroom drains. This helps eliminate the breeding grounds for drain flies to lay eggs. While this method won’t kill existing flies, it may prevent future infestations.

However, be cautious when using chemical drain cleaners. They can be harsh and may damage pipes or harm the environment if not used properly. Always follow the manufacturer’s instructions and consider opting for safer, natural alternatives.

Agardy recommends using a foaming enzyme-based cleaner. It will coat the sides of the pipe and consume materials that could attract drain flies. He added, “In the case of drains with heavy buildup, using a brush in combination with the cleaner is advised as it will physically remove the scum much faster than the cleaner alone.”

Use a vinegar and baking soda mixture 

Pour half a cup of baking soda followed by a cup of vinegar down your drain to create a foaming reaction that may help dislodge organic matter and neutralize odors. 

A clean drain is less likely to attract drain flies. However, this method may be less adequate for severe infestations, and repeated applications may be necessary.

Pour boiling water down the drains

Here’s an easy method to try: Boil water and pour it down your drains to kill drain fly larvae and flush away organic matter. You can also increase the effectiveness of this method by adding a little bleach to your water.

However, be cautious when handling boiling water to avoid burns, and make sure you’re not dealing with any plastic pipes that the heat may damage.

Set up vinegar traps

This method is typically used to get rid of fruit flies, but it may also help with drain flies. Fill a small bowl with apple cider vinegar and add a few drops of dish soap. Cover the bowl with plastic wrap and poke small holes in it. The vinegar attracts drain flies, while the soap breaks the surface tension and causes them to drown.

Vinegar traps are effective but may not wholly eliminate drain flies and should be used as part of a multimodal approach.

Buy commercial drain fly treatments

These treatments typically consist of foams, gels or sprays specifically formulated to target drain flies and their larvae.

While convenient and often effective, commercial treatments may contain harsh chemicals and should be used cautiously, especially in households with children or pets. Additionally, they may be more expensive than do-it-yourself (DIY) methods and require multiple applications to eliminate the infestation.

How can you prevent drain flies from returning?

After tackling a drain fly infestation, preventing them from returning is essential for keeping your home healthy and safe for your loved ones. Here are some practical tips to keep drain flies at bay:

• Regularly clean your drains to prevent organic material buildup that serves as a food source and attracts drain flies.
• Run hot water down drains once a week to help dissolve buildup and flush away potential breeding grounds for drain flies.
• Address plumbing issues with DIY repairs or call a plumber as soon as possible to prevent moisture buildup that can attract drain flies.
• Install drain covers to trap hair, food particles and other debris.
• Maintain proper ventilation in bathrooms and kitchens to prevent moisture buildup in which drain flies can thrive.

Do you need an exterminator for drain flies?

While many drain fly infestations can be managed through DIY methods, calling a professional exterminator may be necessary in some instances. If the infestation is severe or persistent or you lack the time or expertise to tackle it yourself, a pest control professional can provide effective solutions. These may include specialized treatments or addressing underlying plumbing issues.

When deciding whether to call in a pro, you should watch for these signs:

• Repeated unsuccessful attempts at eliminating drain flies
• Widespread infestation throughout the home
• Noticing other pests alongside drain flies

What are drain flies?

It’s helpful to understand what you’re dealing with as you attempt to get rid of drain flies.

Drain flies, also known as sewer gnats, filter flies or moth flies, are part of the Psychodidae family. They’re relatively common household insects that thrive in moist environments near drain pipes or sink drains (hence their name). Sewer flies can seemingly appear out of nowhere, and while they may resemble fruit flies, this pest has distinct behaviors and habitats that make it a unique nuisance in residential settings.

What do drain flies look like?

Adult drain flies have six legs, two wings and antennae. They’re quite tiny, about 1/6-inch long, with a light gray or tan body accompanied by light-colored wings. Their wings have a distinctive vein pattern and are covered in little hairs. If you crush a drain fly, you’ll notice they leave a powdery residue behind.

Where are drain flies commonly found?

Drain flies like to set up shop in areas with plenty of moisture, such as bathrooms, kitchens and laundry rooms. They tend to congregate in the following areas:

• Near drains
• Around sinks and garbage disposals
• Inside shower areas
• Close to laundry room floor drains
• Next to washing machines

If you have plumbing issues, you’re more likely to have drain flies since they thrive in environments with standing water and decaying organic material.

“Drain flies are always an indication of a plumbing issue. It could be as simple as a plumbing trap has dried out or as bad as a broken pipe underground,” said Agardy. If you suspect a drain fly problem, always check your plumbing for leaks or clogs.

Are drain flies dangerous?

Drain flies may appear harmless, but infestations are associated with potential risks. Here’s why spotting drain flies in your kitchen sink or laundry room can be concerning:

• Sanitary risks: Drain flies are attracted to decaying organic matter and can potentially transfer harmful pathogens to any of your food and surfaces they come into contact with.
• Plumbing issues: As mentioned, drain flies often indicate plumbing problems such as blockages and stagnant water, which could open the door to foul odors and further pest infestations.
• Health risks: While they don’t bite, an overwhelming presence of drain flies can exacerbate allergies and asthma symptoms in sensitive individuals.

To keep your home clean and healthy, deal with a drain fly infestation as soon as possible.

How quickly do drain flies breed?

Drain flies breed rapidly, with a single female capable of laying up to 200 eggs at a time. With a life span of about two weeks and a reproduction life cycle as brief as 48 hours, drain flies can multiply from just a few to large numbers astonishingly quickly.

Act quickly if you notice drain flies buzzing around your sink or shower drain. Waiting will only make the problem bigger.

How do you know if you have drain flies?

If you’re not sure what you’re dealing with in your home, the good news is that spotting drain flies is relatively easy. Here are some telltale signs to look for.

Flies near your drains

When drain flies infest your home, you’ll spot them hovering around drains, especially in the kitchen or bathroom. Spotting drain flies is one of the most obvious and noticeable signs, but surprisingly, it’s often the last to appear. According to Keck, you might only realize you have an infestation once the adult flies emerge and start causing a nuisance.

To confirm if a drain is infested with drain flies, she suggests placing double-sided sticky tape over half of the drain overnight. “If flies are on the underside, they are emerging from the drain. If they are on the top side, they are likely attracted to the drain,” she said.

Larvae in your drains

Drain fly larvae are small, worm-like creatures. They are often white or gray, and you may be able to spot them wriggling around in a drain containing drain fly eggs, signaling an infestation.

Drain flies are often confused for gnats. But gnats are more commonly found in houseplants. Spotting larvae in a drain can help determine which pest you’re dealing with. Getting rid of gnats often involves homemade gnat traps and relocating affected plants.

A foul drain odor

If your drains emit a musty or rotting smell, this can signify a drain fly infestation. The odor occurs due to the decomposing organic matter that drain flies feed on and breed on. However, other plumbing issues can also cause foul drain odor, so it’s essential to investigate other potential causes before coming to a definite conclusion.

What’s next?

After treating an infestation, continue practicing good hygiene habits to deter various pests — including drain flies — such as promptly cleaning up spills, disposing of garbage properly, and regularly cleaning all drains and potential breeding sites.

Look for less common drain fly habitats, such as shallow birdbaths or damp mop heads. Also, regularly inspect and maintain your plumbing system and immediately repair any leaks or stagnant water issues.

If you’re struggling with a persistent or severe drain fly problem, don’t hesitate to seek assistance from a professional exterminator. The best pest control companies know how to handle oversize or difficult drain fly infestations.

Remember, proactive measures, including working with an experienced pro, are vital to keeping your home free from drain flies and other pests.