Will Bleach Kill Drain Flies? Do This Instead

Bleach is often recommended as being one of the best solution to getting rid of drain flies, but can bleach actually kill drain flies? Or better still, should you use bleach to kill drain flies?


Bleach will kill some drain flies but it will not get rid of all of them permanently. It flows way too fast down the drainpipe without soaking up the organic gunk which the drain flies feeds on, and also where they lay eggs. In just a few days, more drain flies will hatch and the cycle continue.

Bleach is also very toxic and dangerous as it produces toxic fumes especially when mixed with ammonia. It is also bad for your plumbing as it corrodes plastic and steel pipes. People on a septic system should especially not use bleach to kill drain flies as it also kills the microbes in the septic tank.

The best way to get rid of drain flies is by starving them. You do that by removing the organic gunk/biofilm in your drainpipes which they feed on and also lay eggs. Once you have removed their food and eggs, kill the remaining ones by spraying them with a dish soap and water solution.

In a Nutshell

Bleach can be effective in killing drain flies when used properly. By pouring a mixture of bleach and water down the affected drain, it can help eliminate drain fly larvae and remove organic matter that attracts them.

However, it’s important to use bleach cautiously, as it can be harmful and should be diluted according to safety guidelines. Additionally, addressing the source of the drain fly infestation, such as removing decaying matter from drains and improving sanitation, is crucial for long-term control.

How to Kill Drain Flies with Bleach


In order to kill drain flies with bleach, you will first need to clean your drainpipes, in the process removing the organic matter which they feed on, and the larvae as well. Only then can you pour bleach down the drainpipe to flush down any remaining gunk and larvae. Don’t use bleach if you are on a septic system.

Are the drain flies coming from your kitchen sink, bathroom sink, shower drain or bathtub drain? There are different ways to clean these drains and I am going to show you exactly how to deal with each.

1. Kitchen or Bathroom Sink

If you look under the kitchen or bathroom sink, you will see a U-shaped pipe which is called a P-trap. This drain trap holds a little amount of water at all times preventing sewer gases from coming up through the drain.


Drain traps also prevents clogs from happening further down in the drainpipe by holding potential clogs there. Due to its shape, the P-trap holds lots of organic matter like foods, grease, hair, dead skin cells and others, which are food for drain flies.

If you can manage to get rid of the gunk then you can get rid of these flies from your home. To do this, you will need to first remove the sink stopper and use a drain cleaning tool to remove as much gunk as possible.

If you don’t have a drain cleaning tool you can straighten a wire coat hanger and make a hook on one side. Use the hook to fish out gunk from the drainpipe.

Alternatively, you can use the P-trap to access the drainpipe. Duck under the sink and disconnect the P-trap. Which is in most cases us usually hand tight. Have a small bucket underneath to collect trapped water and gunk.

2. Shower Drain


Shower drains are usually a favorite spot for drain flies due to all the hair, soap scum, dead cells and other trash trapped inside it. The good thing is that cleaning a shower drain is quite easy.

Shower drain usually have a drain cover that is usually attached using one or two screws. Use a screw driver to remove the screws and lift off the cover. If your shower drain has no screws, look for a slot on the side of the cover, insert the screw driver there and pop it off.

Once the cover is out, use a drain cleaning tool or even the hooked wire coat hanger to remove as much hair and other gunk as possible.

3. Bathtub Drain


Bathtub drains are another haven for drain flies. In order to access the tub drain cover, you will first need to remove the bathtub drain stopper, assuming you have a pop up drain stopper. If you have a trip-lever tub stopper (usually on the overflow) you will just need to remove the drain cover with a screw driver.

Once the bathtub stoppers are out, use the same methods as in the sink and shower drain to clean the drainpipe.

How to Get Rid of Drain Flies with Bleach

  • Once the drainpipes are clean, pour 1 gallon of boiling water to flush down and remain gunk as well as kill drain flies’ eggs.
  • Mix 1 cup of bleach with 1 gallon of water and pour down the drain.  If your drain has an overflow (like the kitchen/bathroom sink and bathtub), don’t forget to pour the bleach solution through it as well. Stick a funnel in the overflow and blast down hot water followed by the bleach solution.

And basically that is how to kill drain flies using bleach.

How to Kill Drain Flies with Vinegar and Baking Soda

If you are looking for a way to get rid of drain flies naturally, vinegar and baking soda solution followed by boiling water will do just that. This is also the best way to get rid of drain flies if you have a septic system.

  • If you suspect your drain is dirty, start by cleaning it with a drain cleaning tool.
  • Pour half a cup of baking soda followed slowly by 1 cup of white vinegar. down the drain Let the solution fizzle for 15 to 30 minutes. If your drain has an overflow, stick a funnel inside it and pour down a small amount of solution. Drain flies lay eggs there as well.
  • After the 30 minutes, dump a gallon of boiling water down the drain to flush out any gunk and drain flies’ eggs still lingering in the drainpipe.
  • Insert the funnel in the overflow drain and blast hot water through it as well.

How to Get Rid of Drain Flies Using Apple Cider Vinegar

Drain flies are natural attracted to the smell of apple cider vinegar and you can therefore use it as a bait and trap them. Here is how to go about it:

  • Pour ¼ cup of apple cider vinegar in a bowl.
  • Cover the bowl with a clear plastic wrap using a rubber band or thread.
  • Use a pin or toothpick to poke several holes on the plastic wrap.
  • Place the bowl near the drain fly-infested drain and leave it for a few hours.

Drain flies will be attracted to the sweet smelling apple cider vinegar, enter the bowl through the small holes on the wrap but will not be able to come out.

How to Get Rid of Drain Flies in Sump Pump Pit

If your sump pump pit is also infested with drain fly larvae, you will need to get rid of them before they multiply and get out of control. Although drain flies are not dangerous, they are not just pleasant to live with.

One of the best and natural way to get rid of drain flies in your sump pump pit is to pour ½ cup of salt, ½ cup of baking soda followed by 1 cup of vinegar down the pit. Leave the solution to fizzle out overnight.

Dump a bucket of boiling water inside the pit in the morning to completely eliminate the larvae. You can also follow it up with diluted bleach to sanitize the system.

There are also other chemical solutions for this problem. You basically spray a chemical that foams around the pit and kills the drain flies.


Killing drain flies is one thing, making sure they don’t come back is another thing altogether. There are a few things you can do to prevent drain flies from coming in your bathroom, kitchen sump pump pit or septic tank.

The first thing is to ensure that your drainpipes are clean at all times. Make it a habit of pouring a half cup baking soda and 1 cup vinegar down your drains and following it with boiling water. Not only does this keep away drain flies, it also prevents sewer gases in your bathroom and kitchen.

Make sure that you have no leaking sewer or stagnant dirty water in your property. Drain flies will not survive unless there is organic waste in a dump areas where they can also lay eggs.

Keep your sump pump pit clean at all times. If you are unable to get rid of drain flies on you own, feel free to contact pest control specialist in your area.

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