What to Pour Down Drain to Kill Roaches

Spotted a few nasty cockroaches in your bathroom or kitchen? Here’s what to pour down the drain to kill roaches and get rid of them once and forever.

There are over 4,000 species of cockroaches or, as some prefer to call them – roach (yet, this creature stays disgusting no matter what) living outside but also inside our homes. [1]

Some of the most common species that happen to infest homes include the oriental roach and the American roach. These species look really nasty, grow up to 3 inches in length (which is quite large you must admit) and have a thick and sturdy shell that grows even sturdier as they grow older.

Roaches live very long, even when they are left without oxygen for up to 6 hours, and actually can live even without heads. American and oriental roaches easily find their way into homes through small openings (despite the fact their shell is sturdy, roaches are quite flexible), and, once they are in, they won’t have to leave, like ever.

Roaches eat and breed inside drains and sewer holes but that doesn’t mean they won’t start exploring other areas. They will look for more food, or tastier food, and guess where it can be found. Exactly, inside your home.

Roaches wait until the night falls since people sleep at night and drains are not filled with water, which makes them easy to crawl up. If you happened to find some roaches in the bathroom at night, now you understand how they ended up there.

What to Pour Down Drain to Kill Roaches?


We will suggest 3 great solutions for getting rid of roaches as well as their eggs and babies since entire colonies of roaches live in the drains. Our suggestions – bleach, white vinegar, and ammonia can definitely help with killing every living creature inside the drains, including eggs and baby roaches.

We just have to mention that, if the roach issue has gotten too serious and if you gave these animals more than enough time to make real colonies, you will probably have to contact and hire a roach exterminator.

However, as weird as it sounds, the roaches may persist and stay in your drains even if you already had hired some roach exterminators. Eliminating roach infestation is a challenging task and bugs may start appearing again if the eggs and babies weren’t eliminated along the way.

This happens when drain holes, that act as buffer zones, are not treated properly.

How Come Roaches Climb Drains So Easily?


Cockroach species such as German or smokey brown roaches, both quite small in size, can climb drains and pass through shower holes with no bother. Cockroach adults tend to search for new sources of food, outside drains, and leave their nests.

Then, once they get inside your home, they will start eating various types of waste such as hair and nails, mold on your bathroom floor, and get into trash bins to see if there is anything interesting as well.

Cockroaches are very sneaky and hide well, which is why they are active mostly by night – they don’t want people to find them. How do you know roaches have passed through the holes and entered your bathroom then? Wet smear marks on your bathroom floor are the most reliable indicator that cockroaches have been around.

On the other hand, Florida wood and American roaches struggle with passing through tiny holes such as shower holes. However, regardless of the cockroach size, water inside drain pipes is the most important factor that allows or prevents cockroaches from climbing up drains.

Cockroaches hate water and can’t cross that barrier, which is why water standing inside drain pipes can prevent roach infestation. Needless to say, the lack of water barrier inside your drains (bathroom (shower) and sink (kitchen)) opens the door to roaches to invade your home.

You remember that we talked about how long-lived and cagey roaches are, right? Yet, their main and the most important flaw is the fact that they don’t know how to swim [2].

To get rid of cockroaches in drain pipes, you can go for a trap primer as an easy solution. Just remember the rule – you will need the same number of traps as the number of your water supply sources.

The trap primer ensures there is always enough water inside and refills the trap as needed, ensuring that cockroaches can’t pass through. This roach-preventing method is used in many commercial buildings and homes alike.

Other bugs besides cockroaches live in many people’s drains. Do you know which ones, how to get rid of them, or how to stop them from climbing our drains?

4 Home Made Solutions To Kill Roaches


If you want to kill roaches living in your drain, use one of the following solutions:

  1. Boiling water,
  2. Ammonia,
  3. Bleach,
  4. Vinegar and baking soda.

We would suggest applying either of these methods late at night, ideally, around midnight, for obvious reasons we elaborated on in the previous two paragraphs.

1.     Boiling water

Using boiling water is the simplest, most straightforward solution you can use to kill roaches in your drains. Boil 2 gallons of water, pour it down the drain all at once, then flush the killed roaches with tap water after 10-15 minutes.

Remember that this method works best if you have just spotted a roach or two and it is not as efficient if you are dealing with a cockroach contingent. If you decide to go for this solution, repeat the same process within 3 to 5 days to make sure no roaches or baby roaches are left in your drain.

2.     Ammonia

Ammonia is the next option if you want to kill roaches in your drain. Mix 1 gallon of boiling water with 2 cups of ammonia and flush your drain with this solution. Ammonia has a nasty smell, which is why some people stay away from it, but it is very efficient when it comes to destroying both grown roaches and their eggs.

If you have been seeing roaches walking around your home lately, we highly suggest you make a homemade spray by mixing ammonia and water and pouring the mixture into a spray bottle. Spraying this mixture directly onto cockroaches will kill them instantly.

3.     Bleach

Looking for an immediate roach-killing solution? Bleach is the way to go! You can either use tablets or bleach powder – both will do wonders with roaches. Just make sure that you are making a strong bleach solution if using bleach powder since you will have to mix it with water.

If you want to go for bleach tablets, make a mix of 1 liter of water and 20 tablets to make a strong and concentrated solution. Do not leave the mixture to sit for too long but rather use it right away after preparing it. If you don’t use it immediately, the mix may lose some of its efficacy.

Let the mixture do its thing for about 20 minutes (should be enough to kill all the roaches in your drain) and flush it with regular water to get rid of the dead roaches as well. No doubt, boiling water and bleach will get you superior results when fighting roach infestation.

If you don’t have tablets near at hand at the moment but do have a bleaching solution, simply measure 2 cups and pour them down the drain. Wait for 20 minutes, then flush the drain with pure water. Do not wait longer than 20 minutes since bleach is a strong agent and can make your pipes corrode.

Next, do not apply other methods we listed in this section if you have already poured some bleach down the drain. That means – no vinegar, baking soda, or ammonia should be used for killing roaches if bleach had been used in the first place.

However, you can try other methods 48 hours after using bleach. Why, you may ask. Well, bleach is sticky and it will stay on your drains for a while, all until it is flushed out.

If you decide to use anything else besides bleach, be prepared for a chemical reaction. That means there is a chance toxic fumes may start coming out of the drain that can make you sick. Mixing ammonia with bleach, you can produce gasses that can make you start sneezing, coughing, or dizzy and nauseous.

For these reasons, use bleach alone and also wear some protective gear such as glasses and gloves when working with it to prevent burns or eye/skin injuries.

4.     Vinegar and Baking Soda

Last but not least method for killing roaches that have invaded your drain is – using a mix of baking soda and vinegar. This could be a better alternative to bleach if you already know your drain pipes are not in great condition. All that you should do is mix some white vinegar and baking soda in a cup, stir it well, and pour it down the drain.

In the end, just flush the drains with a bucket of hot water and roaches should be successfully eliminated. If you want to give the baking soda and vinegar mixture even more punch, just some add salt to it.

Does Drain Cleaner Kill Roaches?

We got asked numerous times does drain cleaner kill roaches. Lately, one of our readers asked “will Drano kill roaches”. Drano is an affordable drain-cleaning solution you can certainly use for killing cockroaches in your drain (yet, keep in mind that you won’t kill them instantly).

Chemicals are, in general, not recommended for use on drains since they can cause damage, however, specifically-made drain-cleaning chemicals like Drano are allowed and you can use them for getting rid of insects in your drains.

Can Borax Be Used for Killing Roaches In Drains?


Yes, Borax can be used for killing roach in drains, yet, same as Drano, you can’t expect instant results with it. Borax or boric acid is one of the most popular termite killers and it does kill insects, including roaches, relatively effectively.

When we say relatively effectively, that means you will have to wait for 72 hours for the substance to do its thing and kill all of the roaches in your drain.

Also, boric acid works best when not diluted with water since water makes it lose some of its potency. If you want immediate results, stick with bleach or vinegar and baking soda mix.

How to Stop Roaches From Coming Up Drains? Bonus Tips

In the previous section, we talked about different chemical and non-chemical solutions for killing roaches. Yet, there are more answers to the question “how to avoid cockroaches in bathroom” (or kitchen), and we have listed them below:

  • Go for small-hole bathroom drain covers so that roaches can’t get through them.
  • Even better, use an anti-cockroach drain cover since it is specifically made for preventing roaches from entering your home.
  • Anti-odor drain covers are also an option. Not only these can block roaches from climbing up your drains but they can also prevent bathroom or kitchen drain odors from spreading around your premises.
  • Keep your kitchen and bathroom cabinets clean and closed to make them less attractive to roaches.
  • If there are any crevices or cracks in your kitchen or bathroom, seal them as soon as possible since, otherwise, roaches will find them and use them instead of drains to climb up inside your home. Ideally, you will use urethane foam or silicone for sealing any cracks. If you truly want to have your peace of mind, use copper mesh and steel wool to fill the holes and cracks before sealing them. This is the rule you should be following when dealing with any type of infestation, including rat infestation. We already talked about different types of intruders such as squirrels and rats so make sure to check it out if you have any doubts these animals are posing a threat to your yard, drain pipes, or your home.
  • Do you know what is that one thing cockroaches hate? Peppermint! If you want to drive cockroaches away, spray some peppermint spray on your drain covers. As soon as these bugs smell the strong smell, they will stop trying to climb your drain holes.
  • Another great DIY solution is – a liquid trap seal primer. This product is meant to be used for preventing pipe and drain dry-outs and by using it, you can get rid of roaches for at least 3 to 6 months. You can buy this primer in any hardware store.
  • We can also suggest using a roach killer such as Raid , Hot Shot Liquid Batthat can kill roaches in only 6 hours after being used.

Should I Use Chemicals to Kill Roaches In My Drains?


If you want to protect your drains from potential damage but still kill those roaches, stay away from chemicals. Strong chemicals are deadly for cockroaches but they can also cause costly damage to your drains such as bursting and we guess you don’t want that.

Also, using chemicals too often can actually make your rains clogged since it creates deposits within. We already talked about bleach in the previous sections. For instance, bleach can be used for unclogging drains but it can also make them clogged if used in excess amounts.

Almost needless to say, by pouring chemicals down the drain, they will end up mixing with groundwater and pollute the environment. Stick to more natural solutions, hire a professional that knows how to fight roach infestation (since pest controllers can tell how serious the infestation is at any moment), or, at least, do not use these chemical solutions too often.

Related: How To Kill Worms in Toilet 


So, it doesn’t take much to kill roaches in your drain (you can achieve almost instant results or wait for 3 days maximum). All you need is one of the ingredients you probably already have in your home, such as vinegar, baking soda, or bleach. That is, at the same time, the question to your answer “what to pour down the drain to kill roaches”.

You can repeat the treatment after 3 to 7 days to make sure your home and your drains are really roach-free. Another great tip we can give you is that you should keep your drains clean all the time.

This is the most efficient method to prevent a cockroach infestation in the first place. Use a high-quality drain cleaner, clean your appliances and cabinets in the bathroom and kitchen, and you will be safe from roachesa and other pests.