Aug 242011

Where do Fruit Flies in the Bathroom come from?

Check the dust bin: is a swarm of little flies coming out of it when you open it?

When you have your windows open, check to make sure there aren’t any holes or rips in the screens.

Check for some moist areas and try to make them dry.

If you are absolutely sure there is no fruity material available in the bathroom, then it is more likely that you are dealing with a Drain Fly infestation, but who cares about the name.

Most probably the problem is caused by the drain.

Check all your drains:

  • Are there some drains that are rarely used?
    One of the reasons you have a trap in your drain (The curvy piece) is to preventing odors and all kinds of unwanted stuff from the sewer to enter your house.
    The trap holds water to seal off the drain from the sewer.
    If the water level drops too low, the seal is broken and the sewer creatures can enter your house.
  • Large numbers of drain flies can be produced if there is a problem with broken or leaking drain pipes.
    Drain flies can breed in large numbers in the organic debris deposited through the break in the pipe under the slab.
    Adult flies then enter the living space above the slab through cracks in the slab and back through the drain pipe.
  • Sometimes Drain Flies breed in crawlspaces when a drain pipe is leaking into the crawlspace. Inspect the crawlspace if one is present and look for adult flies. Check spider webs for dead moth flies if live ones are not seen in the crawlspace.
  • Don’t forget to check the basement and the garage.
    Sump pits and floor drains, usually found in basements or garages can be breeding grounds for Drain Flies.
  • Check your drains for infection: there may be a lot of organic material (hair, fat, bacteria,…) stacked in your drain that can become a breeding ground for the Drain Flies.
    You can check if the fruit flies are really breeding in the drain by covering the drain with some tape (sticky side down), leaving a part of the drain  (+/- 1/4) uncovered to create some flow of air. Leave it overnight to see if you trapped some of the flies.
  • Drain flies are very clumsy fliers. When you see some concentration of them on a wall, their breeding ground can not be far away.


How to get rid of Fruit Flies in the Bathroom?

Natural Solutions

Re-fill dried out drains with water, so that they are sealed again.

Pouring a large quantity of boiling water in the infected drain should kill a majority of the larvae growing in there.
However some may escape because they are so small, they can survive in air pockets.
So, you should repeat this every day for 3 weeks until you are sure that they are all gone.

A little bit more drastic:

  • Pour 1/2 cup of salt in the drain
  • Add 1/2 cup of backing soda
  • Add a cup of  white vinegar
  • Let it bubble overnight
  • Pour a lot of boiling water to rinse it completely.

If you can reach the drain trap, remove it, so you can give the inside of the drain a thorough cleaning.
Once you have it removed, it may be the opportunity to replace it with a transparent one
This way you can always see what’s going on inside the drain trap and to get rid of some dirt inside without you having to do some plumbing to inspect it.


Use a “snake” in clogged drains to clean the pipes of all gelatinous material.


Chemical solutions


Pour some bleach in the drain.
Let it rest for a couple of hours
Rinse with water.

Try a drain cleaner.


Look here for more ways of getting rid of fruit flies


How to prevent getting fruit flies in the bathroom?

Keep your drains clean.

Repair cracks and little holes in windows. Fruit flies are tiny insects, thy don’t need a lot of space to enter in your house.

Keep the doors shut.