Drain flies may be small, but they multiply fast. Learn how to get rid of them and prevent them from coming back.

Updated: May 22, 2025

If you’ve noticed tiny, fuzzy flies lingering near your sink, shower, or drains, then you may be dealing with drain flies. Also known as moth flies, sewer gnats, or sink flies, these pests thrive in the organic buildup found inside pipes. While they don’t bite, their rapid reproduction can turn a small problem into a full-blown drain fly infestation.

Since drain flies lay eggs inside damp, clogged drains, simply swatting them away won’t solve the problem. Eliminating breeding sites and maintaining clean plumbing are key to keeping these pests under control. Below, we’ll explore how to kill drain flies, remove their eggs, and prevent them from returning.

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Signs of drain flies

Drain flies often go unnoticed until their population grows large enough to become a problem. The first step in how to get rid of sewer gnats, or drain flies, is to know the signs of an infestation. Drain flies tend to stay near their breeding sites, making it easier to pinpoint the source of the infestation.

Here are the most common signs you will see if you have drain flies in your home:

  • Live drain flies: Small, fuzzy flies gathering near sinks, bathtubs, or drains, especially in the evening.
  • Drain fly larvae: Tiny, worm-like larvae may be visible inside pipes, feeding on organic buildup.
  • Musty or damp odor: A foul smell from drains could indicate stagnant water and decaying matter, which most flies are attracted to.
  • Sudden appearance: If you suddenly see drain flies in your home, it’s likely due to a clogged or rarely used drain that has become a breeding site.

With their dependence on moisture and organic debris, drain flies can quickly multiply if you have a neglected drain, leaking pipe, or standing water. Since this can lead to a serious infestation, it’s best to address these issues to get rid of sink flies in your home.

How to get rid of drain flies

Since they breed inside plumbing systems, getting rid of sink flies can be tricky because it requires removing both the adult flies and their eggs. Also, drain flies reproduce quickly, with females laying up to 200 eggs at a time. While adult flies can be swatted or trapped, their eggs and larvae inside drains must also be eliminated to prevent re-infestation.

Here are some DIY methods that you can use in your home to get rid of sink flies.

  • Flush out breeding sites: Use boiling water, baking soda, or enzyme cleaners to break down organic buildup inside pipes.
  • Clean your drains: Use a drain cleaner and scrub brush to break down sludge and bacteria where drain flies breed.
  • Remove standing water: Fix leaks and empty areas where moisture collects to remove potential breeding grounds for drain flies.
  • Use targeted fly traps: Capturing adult flies prevents them from reproducing while you eliminate breeding sites.

Although bleach can kill drain fly larvae and even fruit flies that visit drains, it’s not always the best solution. It may flush out some organic buildup, but it does not completely remove the sludge that drain flies rely on to survive. Enzyme-based drain cleaners or boiling water are often more effective for long-term removal.

Natural remedies

For those looking for natural ways to get rid of drain flies, several household remedies can help remove larvae and prevent future infestations.

  • Boiling water: Pouring boiling water down the drain helps break down organic matter and kill larvae.
  • Baking soda and vinegar: A mix of baking soda and vinegar creates a fizzy reaction that can help loosen the buildup inside drains. However, this method is not always strong enough to kill all drain flies.
  • Salt and baking soda: Sprinkling salt and baking soda inside the drain overnight can help dry out moisture where larvae thrive.
  • Essential oils: Some people use peppermint, eucalyptus, or tea tree oil as a natural repellent, but these don’t eliminate drain fly eggs.

Natural remedies may help reduce drain fly populations, but they often need to be used repeatedly to have a lasting impact.

Traps

Fly traps are an effective way to capture and monitor drain flies while addressing their breeding sites. You can try both natural and store-bought fly traps to get rid of drain flies in your home.

  • Sticky tape traps: Hanging sticky traps near drains can catch adult flies.
  • UV light traps: These traps use light to attract and capture flying insects, including drain flies.

While traps can help control adult drain flies, they won’t eliminate the source of the infestation, so cleaning your drains is still very important.

Insecticides

For persistent infestations, insecticides may be necessary. These products are great at killing adult flies but don’t always eliminate eggs and larvae inside drains, so it’s best to use insecticides along with other methods to get rid of sewer gnats. Some common insecticides used for drain flies include:

  • Residual sprays: Applied to cracks and crevices and resting spots near drains to target adult flies.
  • Drain cleaners and insecticides: Designed to kill drain fly larvae that are inside plumbing systems.
  • Aerosol foggers: Used to eliminate large numbers of adult flies indoors.

However, there can be some concerns with using insecticides since many of them contain harsh chemicals that need to be reapplied regularly to be effective and should not be used near food areas. For long-term control, insecticides should be combined with preventative measures like drain maintenance and moisture control.

Stopping drain flies from coming back

The best way to avoid dealing with drain flies again after an infestation is to eliminate the conditions that attract them, especially excess moisture and organic buildup. Because these flies can return quickly if their breeding grounds are left untreated, consistent maintenance is key to protecting your home from re-infestation.

For long-term prevention, you can:

  • Clean drains regularly: Use a combination of a stiff drain brush and enzymatic cleaners to scrub the inside of pipes and break down the organic film where flies lay eggs. Regular maintenance can prevent buildup from forming in the first place.
  • Keep drains dry: When not in use, especially in guest bathrooms or basement sinks, cover drains or pour boiling water weekly to flush them and prevent stagnant moisture.
  • Fix leaks: Dripping faucets and leaking pipes provide ideal conditions for flies to breed. Repair plumbing issues promptly to eliminate hidden moisture sources.
  • Improve ventilation: Use fans or dehumidifiers in damp areas like bathrooms, laundry rooms, and basements. Proper airflow can help reduce the humidity that drain flies rely on to survive.

Maintaining your drains and controlling moisture in your home is the most effective way to prevent future infestations. With consistent effort, you can protect your home from drain flies and, in general, prevent house flies from invading your space.

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