Flies in drains can be a frustrating and persistent problem for many homeowners. These small pests, often referred to as drain flies or sewer gnats, thrive in the moist and organic matter found in pipes and drains. Their presence not only indicates a potential hygiene issue but can also lead to unpleasant odors and an uninviting environment. Understanding how to get rid of flies in drains is key to maintaining a clean and pest-free home.
How to Identify Drain Flies
Drain flies are small, moth-like insects with fuzzy bodies and wings, typically measuring about 1/8 inch in length. They are often dark gray or black in color and are covered with fine hairs, giving them a furry or fuzzy appearance. A key characteristic of drain flies is their erratic, jumping flight pattern, which can make them easy to distinguish from other household pests. You may notice them resting on walls, near drains, or around damp areas, particularly in kitchens, bathrooms, and basements.
If you suspect their presence, you can perform a simple test by covering the suspected drain with a piece of clear tape overnight. The flies will stick to the tape as they emerge, confirming the infestation. Identifying these pests early is the first step toward effectively eliminating them.
What Causes Drain Flies?
Drain flies are typically attracted to stagnant water and organic material, making drains an ideal breeding ground. They thrive in areas where moisture combines with debris such as hair, soap scum, grease, or food particles. These materials accumulate in drains, creating a slimy film known as biofilm, which provides the perfect environment for drain flies to lay their eggs. Poorly maintained pipes, leaky plumbing, and clogged drains can exacerbate the issue by offering more sites for infestation. Additionally, areas with standing water, such as unused sinks, mop buckets, or floor drains, can also become hotbeds for drain fly activity if left unattended. Identifying and addressing these causes is crucial for preventing and controlling drain fly populations.
10 Methods How to Get Rid of Flies in Drains
1. Identify the Source Drain with a Simple Tape Test
The first and most crucial step is determining exactly which drain is hosting the infestation. While the flies are often seen hovering around sinks or tubs, the actual breeding site may not be obvious. To identify the infested drain, take a piece of clear plastic wrap or transparent tape and cover the drain opening at night, leaving small holes so airflow continues. In the morning, inspect the tape for any flies stuck to the underside. If you see flies clinging to the tape, you’ve likely found the active breeding site. Repeat this process with other drains to locate multiple infestation points if necessary.
2. Flush the Drain with Boiling Water to Dislodge Organic Build-up
Once you identify the problem drain, start by pouring a kettle or pot of boiling water slowly and directly down the drain. This can help dissolve minor layers of organic residue and biofilm that may be attracting the flies. Boiling water is especially effective when poured in the early morning and late at night, when the flies are least active. Though this may not eradicate a full infestation alone, it’s an important part of a larger cleaning routine. For even better results, repeat this twice daily for several days.
3. Use a Vinegar, Baking Soda, and Hot Water Treatment
A natural and effective cleaning combination is baking soda and white vinegar. Start by pouring about 1/2 cup of baking soda into the drain, followed by 1 cup of white vinegar. The chemical reaction creates a fizzy foam that helps lift and dislodge sludge and bacteria. Let the mixture sit in the drain for at least 15–30 minutes, and then pour in a full kettle of hot (not boiling) water to flush it out. Repeat this process every other day for a week. It’s safe, affordable, and great for regular maintenance even after the infestation is gone.
4. Scrub the Inside of the Drain with a Pipe Cleaning Brush
Drain flies breed in the slimy organic film inside drainpipes, especially in the P-trap and the first few feet of pipe. Chemical treatments often miss this gunk unless you scrub it manually. Purchase a long, flexible pipe brush or plumbing snake, then remove the drain stopper and scrub deep into the drain walls. Work the brush in circular and up-and-down motions, then rinse thoroughly with hot water. Removing the slime physically is one of the most effective ways to destroy fly larvae and break the infestation cycle.
5. Apply Enzyme-Based Drain Cleaners to Digest Organic Waste
For a more thorough and long-lasting solution, use enzyme-based drain cleaners. These bio-cleaners use natural enzymes and bacteria to eat away at the organic material in your drains, without the harsh chemicals found in traditional cleaners. Pour the enzyme cleaner into the drain at night and let it work undisturbed for several hours. Unlike bleach or acidic cleaners, enzyme cleaners are safe for plumbing, septic systems, and the environment. Used regularly, they prevent the buildup that attracts drain flies in the first place.
6. Pour a Diluted Bleach Solution to Kill Larvae and Bacteria
In severe infestations, a bleach treatment can help eliminate larvae and bacteria. Mix 1 part household bleach with 10 parts water, and slowly pour it down the infested drain. Allow it to sit for 10–15 minutes before flushing with plenty of warm water. This method is effective in killing biological organisms in the drain but should be used sparingly, especially in homes with septic systems. Also, avoid mixing bleach with other cleaners (like vinegar or ammonia), which can create dangerous fumes.
7. Set DIY Drain Fly Traps to Reduce Adult Populations
While cleaning kills larvae and eggs, adult drain flies need to be caught and removed during the process. Create a DIY trap using a shallow bowl filled with equal parts apple cider vinegar and water, then add a few drops of dish soap. Place the bowl near the problem drain overnight. The flies are attracted to the vinegar, and the soap breaks the surface tension, causing them to sink and drown. Repeat for several nights to reduce adult populations while the drain is being treated.
8. Remove and Clean the Drain Stopper, Overflow Plate, and Strainer
Drain flies sometimes breed not in the pipe itself, but in the slimy residue around the drain hardware, like the sink stopper, overflow opening, or strainer basket. Remove the stopper by unscrewing it or pulling it upward. Use an old toothbrush dipped in vinegar or dish soap to scrub the stopper thoroughly. Clean the overflow drain (especially in bathtubs) with a brush or flush it with hot vinegar and water. This physical removal of grime is crucial to eliminate any breeding zones the flies may be hiding in.
9. Treat Unused Drains and Floor Drains Proactively
Flies can thrive in floor drains, laundry sinks, basement utility drains, or unused guest bathroom fixtures. If a drain dries out, it loses the water seal in the P-trap and can allow flies and odors to enter. Pour a quart of water into these drains weekly to maintain the seal, then follow up with enzyme cleaner or vinegar to keep them fresh. Even rarely used drains should be included in your treatment plan to stop migration between drains.
10. Prevent Future Infestations with Weekly Maintenance
After eliminating the current infestation, establish a routine to prevent future outbreaks. Once a week, flush each drain with boiling water or use a baking soda-vinegar combo. Once a month, use an enzyme cleaner as a preventative step. Install drain screens to catch hair and food particles, and avoid pouring grease or starchy foods down the kitchen drain. For homes with older plumbing, consider inspecting the drain lines every year to address deeper issues like corrosion or slow-draining clogs that can attract pests.
Safety Considerations
When addressing drain maintenance and pest prevention, it is important to prioritize safety. Always wear appropriate protective gear, such as gloves and masks, when handling chemicals or cleaning out drains to avoid exposure to harmful substances or bacteria. Ensure proper ventilation if using chemical cleaners to reduce the risk of inhaling toxic fumes.
Additionally, keep drain cleaning products and tools out of reach of children and pets to prevent accidental ingestion or injury. If attempting to unclog or inspect a drain, use the correct tools to avoid causing damage to the plumbing or injuring yourself. When in doubt, consult a professional to handle more complex or hazardous situations. Safety should always be a top priority for maintaining a healthy and pest-free home.
Conclusion
Drain flies can be stubborn, but they are not invincible. By combining mechanical cleaning, natural treatments, traps, and ongoing maintenance, you can effectively eliminate both the adults and their breeding habitat. The key lies in persistently cleaning the drain; once isn’t enough. Repetition, thorough scrubbing, and preventive habits will stop flies at the source and keep your drains clean and odor-free. Thanks for reading our blog post on how to get rid of flies in drains! We hope you found it helpful and informative.
