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How to Get Rid Of the Pesty Drain Flies in your Shower and Kitchen in 5 Simple Steps!

Signs of Drain Flies Infestation

Last weekend has been pretty eventful since the pesty drain flies, which are also known as sink, sewer and even moth flies, have invaded our master bathroom drainage system! As a result, our bathroom ceiling and shower walls were swamped with these annoying moth flies. These pests multiply extremely fast and by the evening, there were well over 40 of them resting and scurrying around!

Here is how a typical drain fly looks like;  they are actually cute looking miniature moths. Drain flies measure about 1.5 to 3 mm long.

Image from Do My Own

From our description in the opening paragraph,  it is very apparent that the drain files infestation has reached a serious state in our bathroom. We were not vigilant and as a result, we were caught off guard when these pests multiply exponentially at an alarming rate!

However, fret not! You can conduct a simple test to find out whether your bathroom, kitchen and service yard drainage has been compromised.


The Drain Test

When the drain flies infestation is in its infancy, the small number of drain files which rest in the ceiling or on walls can be easily overlooked since they are so small in numbers.

1. Cover all drainage outlets

Drain flies breed in moist, humid places where there are organic matter for them to feed on. Hence they usually breed in sinks, bathroom, kitchen and even service yard drainage outlets and in any location where moist decaying organic matter can be found.

Cover all the drain outlets and pipes with clear plastic containers coated with cooking oil. Tape these containers down on the floor with a masking tape.

 2. Wait for 2 days

Leave the drain outlets and pipes covered with the containers for 0ver 48 hours. This is to account for the 48-hour life cycle variation. One female drain fly can lay 30 to 100 eggs and the larvae will emerge within 48 hours.

Counter Clockwise from top left: Drain fly larva, pupa, and adult.
Image from Your Wild Life

Where there is an infestation, the drain flies can be found trapped within the containers when they emerge from their breeding grounds.

Here is what we found after covering the shower drainage for 2 days.


How to Get Rid of the Drain Flies Infestation in 5 Simple Steps

Drain flies are surprisingly resistant; they are hard to drown since they are protected by fine water-repellent body hairs and its eggs are not affected by bleach. Extermination of this household pest means getting to the root of the problem; which is to completely remove the moist decaying organic matter which the drain flies feed on. By making their breeding area as inhospitable as possible, the drain flies will not breed.

The safest approach is to use the supplies found in the kitchen; such as the baking soda and white vinegar.

Weapons of Mass Destruction
These are what you need to arm yourself with!
1. Boiling Water
2. Baking Soda*
3. White Vinegar*
4. Kitchen Scrub
5. Clear Container
6. Moth aka Naphthalene Balls*

* We used the following brands which are cheap and effective.

Images from NTUC FairPrice

Step 1. Get the Boiling Water Ready

After you have identified the sites to clean up, get ready a pot of boiling hot water. Pour the boiling water into the drainage outlet or pipes. Ensure that the sides of the drainage outlet or pipes are also soaked with the boiling water too.

Step 2. Pour the Baking Soda into the Drainage

Pour copious amount of baking soda into the drainage outlets and pipes. Scrub the sides of the drainage pipes with the kitchen scrub thoroughly. Do not forget to cover the opening of the drainage outlets and pipes with baking soda too.

The boiling water treatment will loosen up the grimy sludge at the opening, the sides of the drainage pipes and the bottom of the drain. This makes it easier for the kitchen scrub to remove the grimy sludge.

Step 3. Pour the White Vinegar into the Drainage

The explosive reaction with the white vinegar and baking soda will jolt the remaining grimy sludge loose. Pour more boiling water to rinse away the loosen grimy sludge.

By removing the food source, the drain flies will be unable to thrive. 


Step 4. Eliminate the remaining Drain Flies with Moth Balls

Since the drain flies belong to the moth family, the easiest way to eliminate them is to use moth balls! Moth balls contain naphthalene, which is toxic, so they will kill the rest of the drain flies that emerge from their breeding ground.

Therefore, simply concentrate the moth ball vapor by covering the drainage outlet or pipes with a clear container and the moth balls; this will trap the drain flies with the deadly vapor.  Keep the outlet covered with the moth balls for at least 2 weeks to completely eliminate the drain flies.

Tip: Push the moth balls with cover aside, for the water to drain while you are using the shower. Push back the moth balls with the cover back in place after you have used the shower.

Step 5. Biweekly Maintenance

Even when the drain flies are completely gone, you should keep the drainage outlet or pipes clean by repeating Step 1 to 3 biweekly. This will keep the grimy sludge from building up which will attract the drain flies to start breeding again.


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