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Drain Flies in the Bathroom? Treat the Drain, Not Just the Flies

Those small fuzzy flies breed in the slime inside your drain. Scrub it out, break the cycle with an enzyme gel and trap the adults left over.

By Jamilur Rahman Updated November 5, 2026 · 6 min read

Time
20 min plus a week
Cost
Under $20
Difficulty
Easy
A few tiny moth-like flies resting on white porcelain near a bathroom sink drain
In this guide
  1. Quick answer
  2. Free vs. permanent fix
  3. What you'll need
  4. Why it happens
  5. Try this first (free)
  6. When free fixes aren't enough
  7. Buy the fix
  8. How to get rid of drain flies in the house: check every drain
  9. What to skip
  10. FAQ
  11. Related problems

Quick answer

To get rid of drain flies in the bathroom, kill the larvae in the drain, not only the flies you see. Scrub the drain walls, flush with very hot tap water, then treat the pipe with an enzyme drain gel overnight so the slime they feed on is gone. Sticky traps catch the adults while the last eggs hatch out.

Free fix vs. permanent fix

Free fix · 15 minutes

Scrub the drain and flush with hot water

  • Scrub the drain opening and strainer with a stiff brush
  • Flush with very hot tap water, not boiling
  • Tape the drain overnight to find the one they use
  • Repeat daily for a week

How long it lasts: Often enough for a mild case. Slime left on the pipe walls can bring them back within a couple of weeks.

Most readers choose Permanent fix
Enzyme drain gel (illustration)
Illustration

An enzyme drain gel

Drain flies breed in the film of hair, soap and skin cells on the pipe wall. Hot water and baking soda rinse some of it away. A gel with enzymes or bacteria clings to the pipe and digests the film, so the larvae lose their food and their breeding spot. Bleach and boiling water pass through in seconds.

What to get: Enzyme drain gel

How long it lasts: It keeps working for days while it clings to the pipe walls, and a regular dose keeps the film from rebuilding.

Check price on Amazon

As an Amazon Associate I earn from qualifying purchases.

What you'll need

  • Rubber gloves

    For handling the slime you pull out

    You have it

  • Stiff bottle brush or old toothbrush

    For the drain opening and strainer

    You have it

  • Clear packing tape

    To find which drain the flies are using

    You have it
  • Our pick
    Enzyme drain gel (illustration)
    Illustration

    Enzyme drain gel

    Digests the film the larvae feed on

    Check price
  • Sticky fly traps (illustration)
    Illustration

    Sticky fly traps

    Catches the adults that are still flying

    Check price
  • Long flexible drain brush (illustration)
    Illustration

    Long flexible drain brush

    Reaches below where a toothbrush can go

    Check price

Why it happens

1

Slime in the drain

A film of hair, soap and skin oil builds up on the inside of the pipe. Adult flies lay eggs in it, and the larvae eat it.

2

A drain that rarely gets used

Guest baths, spare tubs and floor drains can sit for weeks. The water seal dries out and the slime sits undisturbed.

3

Damp spots around the drain

Overflow holes, a leaking trap under the sink and a wet bath mat can all hold enough moisture for eggs.

4

A fast life cycle

Eggs hatch in about two days, larvae take a week or two to mature and adults live around two weeks. One cleaning rarely ends it, so you need to keep going for a week or two.

Try this first (free)

Do these in order, starting with the simplest.

  1. 1. Find the breeding drain

    Tool used: Clear packing tape

    Lay a strip of clear tape across each drain overnight. The drain with flies stuck to it is your source. Check the tub, the shower, the sink, the overflow holes and any floor drain.

  2. 2. Scrub it out

    Tool used: Stiff bottle brush or old toothbrush

    Remove the stopper or strainer, put on gloves and scrub the drain opening and as far down as you can reach. The slime that comes up is exactly what the larvae eat.

  3. 3. Flush with very hot water

    Run very hot tap water for a minute. Skip boiling water on plastic pipes, since it can soften or warp the joints.

  4. 4. Treat the pipe overnight

    Tool used: Enzyme drain gel

    Pour enzyme gel down the drain at night, when no one will use it, and leave it for about eight hours or as the label says. Repeat on the label's schedule for a week or two.

    Enzyme drain gel (illustration)
    Illustration

    Tool for this step

    Enzyme drain gel · Digests the film the larvae feed on

    Check price on Amazon

  5. 5. Trap the adults

    Tool used: Sticky fly traps

    Put sticky traps near the drain for a week or two. They catch the adults and show you when the flies are gone.

    Sticky fly traps (illustration)
    Illustration

    Tool for this step

    Sticky fly traps · Catches the adults that are still flying

    Check price on Amazon

  6. 6. Run unused drains weekly

    Run water in guest sinks, tubs and floor drains once a week, so the trap keeps its water seal.

When free fixes aren't enough

If flies keep coming back after two weeks of scrubbing and gel treatment, the breeding site is farther in. That can be a cracked pipe, a leak under the sink, a disposal full of waste, or a sewer line problem. Call a plumber if you also smell sewage, hear gurgling, or see several slow drains. For the ordinary case, the gel is what holds, because flies return for as long as the film is there.

Buy the fix

Still stuck after the free fixes? These are the products we would look at.

Our picks compared
PickProductFixesWho it's forBuy
Best pick
Enzyme drain gel (illustration)
Illustration
Enzyme drain gel
the slime that drain-fly larvae feed on Anyone who has scrubbed once and still sees flies. Check price
Budget pick
Sticky fly traps (illustration)
Illustration
Sticky fly traps
adult flies still flying while the drain gets treated Anyone with a few flies left after the drain is treated. Check price
Best pick
Enzyme drain gel (illustration)
Illustration

Enzyme drain gel

Fixes: the slime that drain-fly larvae feed on

Look for: Enzymes or live bacteria, listed on the label; A gel that clings, not a thin liquid that rinses through; Safe for pipes and septic systems, per the label.

Who it's for
Anyone who has scrubbed once and still sees flies.
Honest downside
You just used a chemical drain opener. Flush well with water first, or the product will not work.
Check price on Amazon
Budget pick
Sticky fly traps (illustration)
Illustration

Sticky fly traps

Fixes: adult flies still flying while the drain gets treated

Look for: Non-toxic glue cards or stakes; Small enough to sit near the drain; A pack of several, since you will replace them.

Who it's for
Anyone with a few flies left after the drain is treated.
Honest downside
You expect them to end the problem on their own. They do not touch the larvae in the pipe.
Check price on Amazon

As an Amazon Associate I earn from qualifying purchases. We don't show prices because they change, so use the button to see today's price.

How we picked: How we picked: this page is based on university extension guidance on drain flies and their life cycle, drain-care directions from product makers and what owners report in reviews. We do not test products by hand.

How to get rid of drain flies in the house: check every drain

  • Shower and tub: the drain, the overflow plate and the stopper.
  • Bathroom sink: the drain, the overflow hole and the trap.
  • Floor drains: pour in water monthly so the trap stays full.
  • Kitchen: the sink drain, the disposal and the trash bin.

What to skip

Aerosol sprays, bleach and boiling water as the only fix

Aerosol sprays kill flying adults for a minute, not the larvae in the pipe. Bleach and boiling water pass through in seconds and leave the film on the pipe walls. Treating only the flies is why they keep returning.

Frequently asked questions

How to get rid of drain flies permanently, for good?
Remove the food and breeding spot. Scrub the drain, use the enzyme gel on schedule, run every drain weekly and fix any leak. Clean the drains monthly after that, and the flies have no place to start again.
How to get rid of drain flies with baking soda and vinegar or other home remedies?
Pour half a cup of baking soda, then a cup of vinegar down the drain, leave it 15 minutes and flush with hot water. It loosens some film, but it rinses through quickly. Scrubbing and an enzyme gel do more.
How to get rid of drain flies in the shower, house or kitchen?
The steps are the same for every drain. In the kitchen, also check the garbage disposal and the trash can. In the shower, scrub the strainer and the pipe below it.
How to get rid of drain flies quick?
There is no instant fix. Sticky traps catch adults within a day, but the larvae need one to two weeks of drain treatment to finish.
Are drain flies harmful?
They do not bite or sting. They are a nuisance and a sign of slime in the drain. A large number can mean a leak or a sewer issue, so call a plumber if they will not go.

As an Amazon Associate I earn from qualifying purchases. Affiliate disclosure

Enzyme drain gel (illustration)
Illustration

Our pick: Enzyme drain gel

Check price