How to Get Rid of Frain Flies?

Written by Jack Hayes

Last updated on July 2, 2026

To get rid of drain flies, start by removing the buildup inside the drain, not just the flies you see near the sink. These small flies often appear around bathroom drains, kitchen sinks, showers, floor drains, or toilets where moisture and organic material collect.

These tiny moth-like flies are more annoying than harmful, but they can keep returning if the drain source is not cleaned properly. This guide explains what causes drain flies, where they come from, and how to remove them the right way.

Key Takeaways

◉ Drain flies usually come from slimy buildup inside drains, not from the open room.

◉ Common drain fly spots include sinks, showers, floor drains, toilets, and basement drains.

◉ The best way to get rid of drain flies is to scrub the drain walls and remove the organic film where larvae grow.

◉ Bleach, boiling water, and Drano may kill some flies, but they often miss the main breeding source.

◉ To prevent drain flies, keep drains clean, dry, flushed, and free of buildup.

What Are Drain Flies?

Drain flies are small, fuzzy flies that often appear near sinks, showers, tubs, floor drains, and toilets. A drain fly usually looks like a tiny gray or brown moth with rounded wings and a fuzzy body.

They are weak flyers, so you may see them resting on walls, tiles, mirrors, or sink edges. Tiny baby drain flies are usually not flying yet. They begin as larvae inside wet drain buildup, where they feed on organic slime.

Why this matters: if you only kill the adult flies, the larvae inside the drain can keep turning into new flies.

Drain Flies vs Fruit Flies, Gnats, and Sewer Flies

Drain flies, fruit flies, gnats, and sewer flies can look similar at first, but they come from different sources. Drain flies usually come from slimy drains, fruit flies come from ripe fruit or food residue, and fungus gnats often come from wet plant soil.

A simple way to tell the difference:

◉ Drain flies look fuzzy and rest near drains
◉ Fruit flies are tiny, smooth, and gather near fruit or trash
◉ Fungus gnats are thin and often fly around houseplants
◉ Sewer flies are usually another name for drain flies

Why this matters: the wrong treatment wastes time. If the flies are coming from a drain, fruit fly traps alone will not fix the source.

Are Sewer Flies the Same as Drain Flies?

Yes, sewer flies are usually the same pest as drain flies. People call them sewer flies when they show up near bathroom drains, basement drains, toilets, or areas with plumbing odors.

To get rid of sewer flies, clean the drain walls, remove organic buildup, and treat the source where larvae are growing. Killing the adults helps, but the drain must be cleaned to stop them from returning.

What Causes Drain Flies?

Drain flies are caused by moisture and organic buildup inside drains or plumbing areas. They often appear when sludge, soap scum, hair, grease, or food residue collects inside a drain pipe.

You may have drain flies if a sink, shower, tub, floor drain, or toilet area stays damp for long periods. They are attracted to standing water, drain slime, sewage odors, and decaying material.

Why this matters: drain flies do not need a big mess to survive. A thin layer of buildup inside the pipe can give them enough food and moisture to breed.

Where Do Drain Flies Come From?

Drain flies usually come from sink drains, shower drains, floor drains, basement drains, toilets, or plumbing lines with organic buildup. If you see flies coming out of a drain, the breeding source is likely inside the pipe.

Sometimes people think fruit flies are coming from drains too. That can happen if food residue is trapped in the drain, garbage disposal, or sink area. The key is checking where the flies gather most.

Action step: place clear tape over part of the drain overnight. If flies stick to it by morning, that drain is likely active.

What If Drain Flies Are Not Coming From the Drain?

If drain flies are not coming from the drain, check wet mop buckets, floor cracks, sump pits, leaky pipes, damp basements, dirty trash bins, or old standing water.

They need moisture and organic material. If the drain test shows nothing, the source may be another damp spot nearby.

Why Drain Flies Come Back Even After Cleaning the Sink

A homeowner notices a few tiny flies near the bathroom sink and thinks they came in from outside. They clean the counter, rinse the sink, and spray the flies they see. For a day, the bathroom looks clear.

Then the flies come back. After trying sprays and basic drain rinsing, they call us because the problem keeps returning.

During the inspection, the bathroom looks clean on the surface. But inside the sink drain, there is slimy buildup on the pipe walls that regular rinsing never reached.

That hidden film is enough for drain fly larvae to keep growing.

Once the drain is scrubbed properly and treated with an enzyme drain cleaner, the activity starts dropping. That’s why drain fly control starts inside the drain, not on the walls where the adult flies rest.

When Clear Answers and Professional Service Make a Difference

When a drain fly problem keeps coming back, homeowners want more than a quick visit. They want someone to listen, inspect carefully, and explain what is going on.

One homeowner shared that after dealing with rushed service and unreliable results elsewhere, they were glad to find Agile Pest Control, a smaller local company that took the time to understand the problem. They mentioned that the team was professional, friendly, fair, and easy to talk to.

That matters with drain flies because the source is not always obvious. A good inspection looks beyond the flies on the wall and focuses on the drain, moisture, buildup, and hidden areas that may be keeping the problem active.

How to Get Rid of Drain Flies

To get rid of drain flies, clean the drain walls where the eggs and larvae are living. Spraying the adult flies may reduce what you see, but the problem returns if the drain slime, moisture, and organic buildup stay in place.

Start with this process:

◉ Scrub the drain with a stiff drain brush
◉ Remove hair, grease, and sludge from the pipe walls
◉ Clean the drain cover and surrounding sink or shower area
◉ Use an enzyme drain cleaner to break down buildup
◉ Place sticky traps near the drain to catch adults
◉ Repeat cleaning for several nights if activity continues

Why this matters: drain flies breed inside the buildup, not on the surface. The best way to permanently get rid of drain flies is to remove the material they feed on and keep the drain dry when not in use.

How to Kill Drain Flies

To kill drain flies, target both the adult flies and the larvae inside the drain. Adult flies can be caught with sticky traps or killed with direct-contact spray, but larvae need drain cleaning.

The best approach is:

Use sticky traps near sinks or showers
Scrub the drain with a drain brush
Apply an enzyme-based drain cleaner
Clean nearby walls, tiles, and sink edges
Keep the area dry overnight when possible

Why this matters: killing the flies on the wall only handles part of the problem. If larvae remain inside the pipe, new flies can appear again within days.

Will Bleach Kill Drain Flies?

Bleach may kill some drain flies on contact, but it often flows past the slimy buildup where larvae live. It can reduce odor for a short time, but it usually does not fully remove the breeding source.

Does Boiling Water Kill Drain Flies?

Boiling water may kill some larvae near the surface, but it does not always remove grease, sludge, or pipe buildup. It may help as a small step, but scrubbing the drain is still more effective.

Will Drano Kill Drain Flies?

Drano may clear certain clogs, but it is not made as a drain fly treatment. Drain flies need the organic film inside the pipe removed, so a drain brush and enzyme cleaner usually work better for long-term control.

How to Get Rid of Drain Fly Larvae

To get rid of drain fly larvae, clean the wet buildup where the larvae are feeding. These larvae can look like tiny worms in drains, toilets, shower drains, or septic-related areas.

Start by scrubbing the inside of the drain with a stiff drain brush. Focus on the pipe walls, drain cover, overflow opening, and any slimy buildup around the opening. Then use an enzyme drain cleaner to break down the organic film left behind.

If you see larvae in a toilet, shower, or floor drain, check for standing water, sewer odor, leaks, or septic issues. Killing the larvae matters, but removing the breeding material is what stops new adult flies from appearing.

How to Get Rid of Fruit Flies in Drains

To get rid of fruit flies in drains, clean out the food residue and buildup inside the sink drain or garbage disposal. Fruit flies are often attracted to rotting food, sticky liquids, grease, and fermenting residue trapped in the drain.

Start with these steps:

◉ Scrub the drain opening and pipe walls
◉ Clean the garbage disposal if one is present
◉ Remove food scraps from the sink area
◉ Use an enzyme drain cleaner for organic buildup
◉ Set vinegar traps near the sink to catch adults

Bleach may kill some fruit flies on contact, but it often misses the material they are feeding on. A good fruit fly drain treatment should remove residue, not just mask odor.

How to Prevent Drain Flies

To prevent drain flies, keep drains clean, dry, and free of organic buildup. Drain flies return when moisture, sludge, hair, soap scum, grease, or food residue collects inside pipes.

Simple prevention steps:

◉ Brush drains regularly
◉ Flush unused drains weekly
◉ Fix leaks around sinks and toilets
◉ Clean garbage disposals
◉ Remove hair and debris
◉ Keep floor drains from drying out
◉ Watch for sewer odors

Why this matters: drain flies need moisture and buildup to breed. Once drains stay clean and water issues are fixed, they have fewer places to grow.

Still Seeing Drain Flies Around Your Sink or Shower?

If drain flies keep showing up after cleaning, the source may still be inside a sink drain, shower drain, floor drain, toilet area, or hidden moisture spot. Adult flies are easy to notice, but the real problem is often the slimy buildup where larvae are growing.

AgilePests can inspect the affected areas, identify where the drain flies are coming from, and explain what needs to be cleaned, treated, or corrected. Once the source is found, it becomes much easier to stop the activity and reduce the chance of the flies returning.

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