Where Do Roaches Come From in the Bathroom? | Information and Control Guide

The bathroom is one of the most favorite areas in a house that roaches love to stay in, besides the kitchen. You may see them crawling on the wall, hiding behind the toilet bowl, or even swimming in the toilet bowl.

However, seeing a single cockroach inside your bathroom does not necessarily mean that it is alone.

Where do roaches come from in the bathroom? No one knows where exactly they come from. But since roaches need moisture to survive, most of them are very likely to have come from a sewer system. Some of them may have been hiding in the kitchen since this is the ideal place where they can find food.

Cockroaches are not only disgusting pests; they also contaminate the food that can cause food poisoning. Their feces and crushed body fragments can also trigger asthma and can lead to allergic symptoms when inhaled.

Since all of us go to the bathroom, this guide will teach you how to deal with roaches in bathrooms.

Why Do Roaches Like Bathrooms?

Why Do Roaches Like Bathrooms

Roaches like bathrooms mainly because of the moisture, although there are also other places where they can hide. This is also why they love to hide in drains, kitchen sinks, leaky pipes, and other secure areas in the house with plumbing problems. They may also accidentally enter the bathroom in search of food.

Why Are There Big Roaches in My Bathroom?

There are big roaches in your bathroom because they are very attracted to water. They need water to survive and reproduce. Bathrooms are also usually dark, which makes them ideal as their hiding places to avoid humans.

Regardless of how clean your bathroom is, roaches may still invade it, especially at night.

Where Do Roaches Stay Before Entering Your Bathroom?

Where Do Roaches Stay Before Entering Your Bathroom

Roaches that are in the bathroom could be from everywhere. Most cockroach species, especially American cockroaches and German cockroaches are nocturnal creatures, which means that they may have already entered your house without your knowledge and are hiding in small, dark, places, especially at night.

Since cockroaches love moisture, they may have been your sewer system for a long time. Amazingly, they can hold their breath under the water for about 30 minutes.

Despite not being great swimmers, some of them can swim to the floor drain of your bathroom and can somehow enter even if the drain is firmly covered.

Can Cockroaches Come Up Through Toilets?

Cockroaches cannot come up through the toilet unless you have a clogged toilet or it has a poor design. Generally speaking, all toilet bowls should have a water trap, which blocks poisonous sewer gas from rising and entering your house. This curving channel connects the base of the toilet bowl to the drain pipes.

After flushing the toilet, the water trap retains some water, which acts as an air seal. Although roaches can survive long underwater, they are bad swimmers.

This is why they are very unlikely to come up through your toilet. If you see some roaches in your toilet bowl, they probably fell from the toilet rim or other surfaces.

How Do Roaches Get Inside Bathrooms?

How Do Roaches Get Inside Bathrooms

Roaches have a lot of ways to get into your bathroom. Aside from small cracks or gaps in the door and windows, they can also enter by passing through the floor drain.

Cockroaches are smart enough to find ways to drain pipes, whether they are wet or dry. Interestingly, some of them can go through dry water traps.

Do Dead Cockroaches Attract More?

Do Dead Cockroaches Attract More

Dead cockroaches attract more of them. Roaches are generally omnivorous scavengers and eat almost anything, including their dead comrades. In fact, they may also eat their young and eggs once food becomes scarce. Aside from that, big roaches will eat dead cockroaches if they are stuck in overcrowded places.

What Do Cockroaches Hate?

What Do Cockroaches Hate

Cockroaches hate moving air, bright light, and extremely high or cold weather because they are cold-blooded creatures. Typically, roaches cannot reproduce once the temperature is above 115°F (46.1°C) or below 45°F (7.2°C). If the temperature is below 14°F (-10°C), they may die within one hour or less.

How to Get Rid of Roaches in Bathroom?

Roaches in the bathroom can be a very frightening scene. If you are afraid of cockroaches, you are very likely to scream and run away.

On the other hand, if you are brave enough, killing them one by one should solve the problem. If there is already a lot of them, here are some effective ways to get rid of roaches in your bathroom:

  • Stomp on them. If you are barefooted or cockroaches are on the wall, hit them with any hard object.
  • Use a handheld, wet and dry vacuum cleaner to catch them.
  • Remove the dead cockroaches at once, and clean the area thoroughly that can attract other roaches.
  • You may also pour boiling water directly to them, and they will die instantly.
  • Alternatively, add soap to the hot water and spray it on them.
  • If you have an open trash can inside your bathroom, chances are other roaches are also inside. Use a roach spray such as Raid Ant & Roach Killer that kills cockroaches on contact.

How to Get Rid of Baby Roaches in a Bathroom?

Commonly known as nymphs, baby roaches look like adults except that they are wingless and are much smaller. Nevertheless, they can run almost as fast as adults and therefore\ can hide better.

Since baby roaches are also attracted to moisture, they may also be in bathrooms. Here are some ways to get rid of them:

  • Step on them or hit them as you do to adult roaches.
  • Spray soapy water on them and in areas where they could possibly be hiding.
  • Aside from sticky traps with bait, you may also sprinkle some industrial-grade boric acid on the bathroom floor at night before going to sleep.
  • Spray insect growth regulators (IGR) such as Zoecon Gentrol Insect Growth Regulator. IGRs don’t kill roaches but rather prevent baby roaches from growing into adults, thus making them unable to reproduce.
  • Use a wet and dry vacuum cleaner such as Stanley SL18116 Wet/Dry Vacuum. This can also fix your clogged drain. But because some baby roaches may still survive while inside the vacuum bag, throw it away at once or pour boiling water in it.
  • Avoid using bug bombs or total release aerosols. Aside from being flammable and a fire hazard, baby roaches can avoid them by hiding in small gaps.

How to Prevent Roaches in Bathroom?

Preventing roaches in bathrooms means giving them reasons not to be there and blocking their way in. This is because they will not stay long in places where they cannot survive and reproduce.

If you think keeping your bathroom free from cockroaches is not possible, here are some useful tips you can easily follow:  

  • Fix clogged sinks, toilets, and leaky pipes under your bathroom sink.
  • To keep your bathroom free of moisture, turn on the bathroom exhaust fan right after taking a bath. Leave it running for about 20 minutes.
  • If you have a pail or water bucket inside your bathroom, always cover it when not in use.
  • Empty your garbage can in your bathroom regularly and clean it thoroughly. Make sure the cover has no gap.
  • If you will leave the house for quite some time, sprinkle diatomaceous earth (DE) in areas where roaches may hide. DE is not toxic to humans and pets unless inhaled.
  • Don’t let the toilet water trap run dry. If the trap primer is not working properly, replace it with American Standard Trap Primer or call a professional plumber to help you.
  • You may also install a one-way trap guard on your drain. Products such as G Green Drain Waterless Trap Seal allow water to go down but not debris that can cause clogging.
  • To help control the high humidity level inside your bathroom, try installing a portable dehumidifier such as Pro Breeze Electric Mini Dehumidifier. Just don’t forget to empty it regularly.

How to Keep Roaches Out of Bathroom?

The best way to prevent roaches from invading your bathroom is not to allow them to enter your house. Again, cockroaches are very attracted to moisture, human food, garbage, and protected areas, where they can lay eggs. Therefore, proper sanitation will be a great help. Here are some of the things you can do:

  • Inspect your food, groceries, and belongings before bringing them inside your house.
  • Wash the dishes right after eating, and always keep your dish cabinet dry and closed. Clear your dining table properly, and make sure no food debris is left.
  • Remove water from the pan under your refrigerator regularly, and always keep the area dry.
  • If you have pets, remove leftover food immediately and clean their bowls thoroughly. Place dry pet food in properly sealed containers.
  • If you have indoor plants, don’t overwater them. Excess water will attract cockroaches.
  • To help prevent cockroaches from gaining access to attics and windows, install a fiberglass window screen over vent pipes on your roof.
  • Always keep your doors and windows closed. If possible, place screens on them. 
  • Alternatively, install a door sweep at the bottom of your door. Products such as Baining Door Draft Stopper Door Sweep don’t only prevent roaches from entering a door; they also prevent dust and debris from coming in. 
  • Remove debris outside your house, especially those that roaches can use as shelter. Also, stack firewood far away from your house.

What Do You Pour Down the Drain to Get Rid of Cockroaches?

Cockroaches are very unlikely to live in a drain, but they can use it to enter your bathroom and kitchen or to get food and moisture.

They may also accidentally drop into the kitchen sink, making them unable to escape and get stuck in the drain. To get rid of roaches in your drain, here are some solutions you can pour:

1. Bleach Solution

Bleach alone kills roaches effectively, but it releases toxic fumes and can also damage your drainage system. Mixing bleach with ammonia or other cleaning chemicals also poses health risks. So, if you decide to pour bleach into your drain, wear a protective mask and gloves, and don’t use too much of it or too often.

2. Boiling Water

Pouring boiling water into your drain can kill roaches of all life stages. However, some cockroaches may crawl deeper into the drain once they feel the hot water. Hence, water may no longer be too hot once it reaches them. For better results, add soap into the hot water and pour the mixture several times as fast as you can.

3. Baking Soda and Sugar

Contrary to popular myth, baking soda will not kill cockroaches in drains unless they eat it. But since baking soda has a very unpleasant taste for them, they are very unlikely to ingest it. Therefore, you might want to add some sugar as bait – one part sugar, one part baking soda. Once roaches eat the mixture, they will die.

Related: How to Keep Roaches Away While You Sleep? | A Detailed Guide


Saying that only dirty houses attract cockroaches is not true. Nonetheless, a house free of clutter and cleaned regularly makes it an unsuitable place for them.

Likewise, clean and dry bathrooms will also discourage roaches from entering. Once they cannot find food and water, they will find another place to stay.

List of Sources

The Cockroach FAQ

Cockroach Biology and Management

Cockroach Control Manual

Least Toxic Methods of Cockroach Control