Will Bleach Kill Drain Flies? [Top 4 Alternatives]

Bleach should never be poured down a drain to kill drain flies. Not only is bleach ineffective at killing drain flies, but it can also release toxic fumes, will not clear clogs, and can cause serious harm to septic tanks. Instead, use a drain cleaner product, a vinegar solution, or boiling water to kill drain flies in your plumbing. Then, use fly traps to catch adult drain flies and eliminate the infestation.

Will bleach kill drain flies?

Why Should You Not Use Bleach to Kill Drain Flies?

Pouring bleach down your drain won’t kill many drain flies. Drain flies breed where bacterial buildup forms on the walls of pipes. This typically occurs when a drain is partially clogged or is slow-draining. Household bleach doesn’t work to unclog drains. So, even if the bleach kills some bacteria and drain fly larvae inside your plumbing, it won’t solve the problem that led to your drain fly infestation in the first place.

  • Bleach will not break up clogs that create the environment for drain fly infestations.
  • Pouring bleach into your drain can release corrosive, toxic fumes that are dangerous to you and your family.
  • Septic systems can be damaged by pouring bleach into your drain.

Bleach is an especially poor choice for drains infested with drain flies because of the dangers bleach poses. When you pour it down your drain, bleach can react with other materials to release toxic fumes that can irritate your eyes and airways. It can also destroy the helpful bacteria in a septic tank, seriously harming the functionality of your septic system. So, the best course of action is to leave the bleach on the shelf if you have a drain fly problem.

4 Best Ways to Kill Drain Flies Without Bleach

There are several far safer, more effective alternatives to bleach when it comes to killing drain flies. If you want to kill drain flies quickly, use these techniques:

Drain Cleaner

An enzyme-based drain cleaner is one of the best tools for killing invasive drain flies. A good enzyme drain cleaner will clear clogs that encourage drain fly breeding grounds. As it works, it destroys the bacterial buildup in your pipes. It will also kill the eggs drain flies lay in your drain, along with the drain fly larvae that feed on bacteria in your plumbing.

  • This enzyme-based drain cleaner will kill drain flies more efficiently than bleach.
  • A good drain cleaner will also clear clogs and kill bacterial buildup, which means your drain fly problem won’t return.
  • Drain cleaners are powerful enough to kill drain fly eggs and larvae inside your plumbing.

Drano is also a great tool for getting rid of drain flies and preventing them from returning. Drano products are septic-safe and have similar killing power as enzyme-based drain cleaners. So, you’ll get better, more long-lasting results when you kill drain flies with Drano instead of bleach.


When it comes to killing drain flies with common household products, vinegar is a much better choice than bleach. In fact, there are several ways to kill drain flies with vinegar. You can create a foaming drain cleaner made from baking soda, vinegar, and salt that clears your drain, kills drain flies, and won’t release harmful fumes.

  • Pour 1 cup of baking soda into your drain, followed by ½ cup of salt mixed into 1 cup of vinegar. This homemade foaming drain cleaner will clear clogs and kill drain flies.
  • Attract drain flies to traps and fly strips by using apple cider vinegar.
  • Combine white vinegar with a few drops of dish soap in a spray bottle. Then, spray drain flies to kill them instantly.

Depending on the type of vinegar you use, you can even make traps for drain flies, sewer gnats, and fruit flies. Drain flies are drawn to the smell of apple cider vinegar. So, you can place a dish of apple cider vinegar near a fly strip to attract adult drain flies to the trap. Or, you can kill drain flies instantly with a spray made from vinegar and dish soap.

Boiling Water

It may seem too simple to work, but boiling water is better than bleach for killing drain flies. Whether you’re working to kill pests in shower drains or in your kitchen sink, simply pour 8 cups of boiling water down the drain. Wait for the water to drain, then repeat. The boiling water will kill bacteria and immature drain flies instantly.

  • Bring 8 cups of water to a boil, then pour it down the drain to kill drain flies.
  • For extra killing power, repeat the process with an additional 8 cups of boiling water, just to make sure all the flies are dead.
  • Boiling water kills bacteria, drain fly eggs, and fly larvae on contact.
  • You can safely pour boiling water into any household plumbing system.

Boiling water is a great first choice for controlling pesky sewer flies. It’s perfectly safe for all types of plumbing and is very inexpensive. Just boil a pot of tap water and use it to kill the pests in your drain.

Fly Traps

Bleach may be your first solution for killing flies in a drain, but pouring bleach into a sink won’t kill the adult flies that are buzzing around. In order to kill the mature flies and keep them from reproducing, you’ll need to trap and kill them. You can use commercial fly baits or homemade traps.

  • Bleach won’t kill adult drain flies—you’ll need to trap them.
  • Hang these fly strips near your drain to attract and kill mature drain flies.
  • For more tips, check out the top ways to kill drain flies.

Because drain flies don’t like to fly long distances and prefer to walk, a common fly strip hanging near the infected drain will often kill large quantities of adult drain flies. You can even bait the fly strip by sprinkling some apple cider vinegar on it. This will attract the drain flies so you kill them even more quickly.

How Do You Get Rid of Drain Gnats with Bleach?

If you’re considering using bleach to kill the drain flies in your home, keep these facts in mind:

  • Bleach is not an effective drain fly killer.
  • Pouring bleach into your drains can release toxic fumes, won’t clear clogs, and can harm septic systems.
  • Commercial drain cleaners are far more effective at killing drain flies than bleach.
  • A homemade drain cleaner made from vinegar, baking soda, and salt is a great drain fly killer.
  • You can kill drain fly eggs and larvae by pouring boiling water down your drains.
  • Use fly traps and fly strips to catch and kill adult drain flies.

By using powerful cleaning agents to kill immature drain flies in your plumbing, then following up with traps designed to kill adult drain flies, you’ll get rid of your infestation as quickly as possible. Bleach is great for other household uses, but it should never be poured down the drain.

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