Will Bleach Kill Drain Flies?

If you’ve been invaded by small black flies in your bathroom, these might be drain flies. Also known as sink flies, moth flies, sewer gnats, or drain gnats, these tiny pests don’t bite and are harmless but extremely annoying and shouldn’t be left alone to multiply in your home.

They might be symptoms of a larger problem with standing water and drain clogs.

You may be looking for a quick and accessible home remedy for getting rid of an infestation of drain flies in your home, and bleach is often the most popular go-to substance for killing pests of this kind.

Yes, bleach will kill drain flies. Like all insects, they do not have lungs and instead breathe via tiny openings in their exoskeletons. They don’t want to inhale bleach as it will stop their breathing process.

It can be a useful method if used correctly, but it’s not very practical for large-scale eradication because the use of too much bleach can damage your drains.

Most of the drain flies will be killed by bleach, but not all of them permanently.

Beach will flow away quickly down your drain pipes without removing the organic matter which the drain flies feed on, which is where they like to lay their eggs. These eggs probably won’t be exposed fully to the bleach so, in just a few days, more drain flies could hatch and the cycle of drain fly infestation continues.

What Is a Drain Fly?

A drain fly, also known as a moth fly or sewage gnat, is a little insect that spends its larval stage in the moist soil at the bottom of organic material. Their larvae are also known as drain worms and can be a pretty disgusting sight in your home.

Drain flies have no preference for the kind of organic material they live in – so long as it’s wet and dark. They will all be found living together. Drain flies can sometimes be mistaken for fruit flies, which is understandable as they are very similar in size and color. However, fruit flies generally inhabit places with rotting food such as fruit and are generally found in kitchen waste areas.

They need water to live and reproduce. This may be the reason why you have been seeing them at home – perhaps your sink or drains are getting clogged up with dirt and dust from another part of the house!

Nevertheless, drain flies will lay their eggs in organic material that has water. This could be a clogged sink or even the bottom of your birdbath. If you spot any signs of these insects in your bathroom, kitchen, and any other parts of the house with drains and sinks – it’s best to get rid of them right away before they have a chance to lay more eggs.

drain fly

What are the Symptoms of Drain Fly Infestation?

If you spot any of these insects in your home, there’s probably an infestation somewhere nearby. But where is it coming from? It may be difficult to determine this because drain flies can come from different sources at once.

Drain flies do not bite and they don’t spread diseases. They do, however, pose a hygiene problem and their infestation will be more than just an inconvenience.

Drain flies like moist and dark spaces – that is why your drains at home are such inviting homes for their larvae! If you spot these insects in various parts of your house – it’s clear that there is a problem with your drains and other possible sources of water.

They will be found in:

  • Basements, garages, washers & dryers
  • Houseplants
  • Birdbaths and pet food bowls
  • Outdoor, uncovered trash cans                 
  • Animal droppings                                             
  • Sewage systems
  • Air conditioning systems

You can find drain fly larvae in any part of the house with a water supply. If you spot them near a window or any damp place – there is likely an infestation nearby.

What Attracts Drain Flies?

Drain flies typically breed in moist environments. They will lay their eggs near areas with standing water and decaying organic matter.

This will include discarded food and sewage or the grime left in your drain pipes over time.

The adults will be attracted to the build of this kind of material because it provides them with a place to lay their eggs and bring up the larva.

Once they hatch, drain flies will be on the lookout for food – which can be found in even more places than you would first expect! This is when you will start to see the drain fies around your bathroom or kitchen area.

Is Bleach Effective Against Drain Flies?

Bleach can be effective at killing drain flies but only if it can penetrate deep into the crevices of your drains where the larvae might be hiding.

The issue here is the decaying material in your drains is not only a source of nutrition for the drain flies but is also providing them with a form of protection.

Most of the drain flies will be killed by bleach, but not all of them permanently. Beach flows away quickly down your drain pipes without removing the organic matter which the drain flies feed on, which is where they like to lay their eggs. These eggs probably won’t be exposed fully to the bleach so, in just a few days, the drain fly larvae will hatch again.

You need something that can actually reach into the drains and clean out all the organic matter that has built up over time.

Will bleach kill drain flies?

How to Kill Drain Flies with Bleach

The best method of using bleach to kill drain flies is to first ensure your drains are clear of as much of the decaying matter that the flies love.

Bleach can be a potent disinfectant and doesn’t need much to be effective, but making sure it reaches the areas it needs to is key. Boiling water can be used to break down the decaying matter, loosen areas that may be clogged, and basically expose the drain fly larvae so the bleach can then have an effect on them.

However, you first need to check the following parts of your plumbing to ensure the clogged up areas are clear:

  1. Check the U-shaped pipe under your kitchen or bathroom sink known as a P-trap. The P-trap’s shape attracts a large amount of organic material, such as foods, grease, hair, dead skin cells, and other things that drain flies like.
  2. Drain flies are attracted to shower drains since they are filled with hair, soap scum, dead cells, and other waste. Remove the shower drain cover and use a wire coat hanger to loosen the decaying material in the pipe.
  3. Drain flies also love bathtubs, with bathtub drains being another refuge. If you have a pop-up drain stopper, you’ll need to take it out first before removing the tub drain cover. Once removed, try the coat hanger method to release any built-up gunk.
blocked bathroom plug hole

Then, try these steps to eliminate the drain flies with bleach:

  1. Fill a bucket of boiling water and pour it down the drain. This will give an initial attempt at releasing most of the build-up of material.
  2. Then mix a bucket of 1 part bleach, 10 parts water
  3. Pour down the drain and leave to sit for 4 hours
  4. Run cold water down the drain to clear
  5. Repeat as many times as you need until you are sure the infestation has been removed

It may need 2-3 cycles of this process to completely clear the problem.

Remember not to use too much bleach in your mixture, the boiling water is doing all the hard work and just allowing the bleach to penetrate the areas it needs to.

Is Bleach The Most Effective Way to Kill Drain Flies?

Using bleach is probably the most convenient and quick solution for a drain fly infestation. Due to most homes having bleach readily available, it is recommended as the go-to substance, however, there are some other household items that could be used if you don’t have bleach:

Vinegar & Baking Soda

If you have vinegar and baking soda in your home, applying a mixture of the two could be an effective killer of drain flies. Remove the drain cover and pour a large amount of vinegar/baking soda mix down the drain, leave it for at least 4 hours, and flush with cold water when finished.

Citrus Oil & Salt

The acidic nature of citrus fruit can dissolve the drain flies’ exoskeleton, resulting in death after around 30 minutes.

Salt is also a way to kill drain flies because it’s poisonous to insects. A mixture of salt and water down your drain could give the same effect as the vinegar method, but without adding an extra smell to the area.

However, bleach is definitely one of the most convenient ways to rid your home of drain flies, but if you only have vinegar or salt at home already it’s probably worth trying that method first before committing to bleach.

The problem with using these methods, though, is that they won’t kill all the larvae in your drains if there is a major build-up of grime and gunk.

How To Stop Drain Flies Returning

Drain flies are generally very easy to get rid of. Usually, boiling water with bleach or some of the other substances named above will do the job.

The most important aspect of this process is how the substances can penetrate the drain fly habitat.

If you’re not correcting the underlying problem of a slow or clogged drain they’re living in, your efforts may be pointless.

Tackling the issue of a clog or trapped decaying matter in pipes or drains should be the main focus of your drain fly eradication strategy.

If you have Drano available in your home it would be our best recommendation in getting rid of the infestation because it will deal with the source of the problem, which is blocked drains.

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