Roaches can drown but not instantly since they can hold their breath in water for 7-15 minutes. Even if you hold a cockroach’s head underwater, it will not drown because it breathes through tiny openings in its body. They do not have a nose for breathing and holding their heads in water cannot kill them.
The only way to drown a roach is to deep and hold its entire body in water for 1 hour or more. Flushing them down a drain will not kill them unless they remain immersed in water for more than 60 minutes.
Naturally, roaches are not heavy enough to sink in water. When dropped in water, they remain floating since they are light with a flat body that cannot easily break water surface tension. They can also close their spiracles for 7-10 minutes and use their feet to swim to safety.
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How long does it take for a cockroach to drown
It takes 10-30 minutes for roaches to drown in water. However, this depends on temperatures. They will die faster in hot water as compared to cold water. Roaches have a circulatory system that is open and hot water can damage them faster than cold water.
Cockroaches can hold their breaths for 30-40 minutes depending on the species and environment. The ability to stay without breathing is what determines the duration it takes to drown them. Roaches that live in homes and areas near the ocean can hold their breath longer than those that live away from water bodies.
When living in dry areas, roaches are naturally adapted to close their spiracles most of the time in order to avoid water loss. Staying without breathing then becomes a daily routine and this can help them stay for up to 30 minutes when drowned.
However, roaches that are commonly found at home live in a good environment with enough moisture I.e drains, sinks, and basements. Those cannot survive for more than 15 minutes when dipped in cold water. Roaches submerged in hot water die in 10-15 minutes.
Normally, roaches can decide to close their spiracles which they use for breathing for some time. This helps in regulating the amount of oxygen in their body since too much can be deadly for them. This explains why roaches cannot drown instantly even when completely covered in water.
The ability to close their breathing holes is what helps cockroaches survive underwater. However, most of them can only last for 7-10 minutes. After 10 minutes, most roaches will yarn for more oxygen and this is when they will open their spiracles. When they do so, water will rush in and they will drown to death.
How to drown a cockroach
Drowning roaches in pure water takes long in general because of the surface tension. Water consists of molecules that are drawn to each other. This bond is what makes little bugs or anything on the surface float since the bond can resist lightweight.
To reduce or break the surface tension in the water surface, you will need to mix it with a surfactant. The most efficient way to drown a roach instantly is to add a surfactant like soap or alcohol. Those will break the surface tension in water and make the roaches drown.
1. Soap + hot water
Without surfactant, roaches will remain floating and this will not kill them. Soapy water kills roaches by blocking breathing spiracles. This chokes their open circulatory system and they will die. In some cases, soap plus water has the ability to make roaches explode.
When cleaning the toilet, it is a good idea to pour half a cup of liquid detergent into the bowl after cleaning. This keeps the water molecules apart and if any cockroach in a toilet bowl falls in it, there are high chances that it will drown.
You can also use soap and hot water to drown roaches down the drain. Mix 2 cups of dish soap with 6 cups of hot water and flush it down the drain. This also helps in disinfecting and removing any foul smell down there. There are no risks of chemical reactions and this makes it safe for drains.
2. Alcohol + water
To drown roaches in water, you can also mix it with Isopropyl alcohol. This reduces the bonding strength and the water molecules will become less resistant. Roaches can then sink with a lot of ease since there the chances of floating are drastically reduced.
Isopropyl alcohol is normally mixed with water to give it antiseptic properties which is similar to rubbing alcohol structure. Rubbing alcohol can kill cockroaches by dehydrating and drying out their cells. Drowning roaches in this kills them instantly.
Pure Isopropyl alcohol works best as compared to rubbing alcohol since the latter is normally mixed with water. However, rubbing alcohol will still give you the desired results as long as you do not over dilute it. A mixture of any of those two diluted in water can also be poured down the drain.
Never pour straight Isopropyl or rubbing alcohol down the drain or sewer. It is advisable to mix them with water and ensure that the ratio of alcohol to water is at least 1:3 parts. This will prevent any vigorous chemical reactions in the drain which can be harmful.
3. Hot distilled water
Drowning roaches in salty water will not be easy because salt will naturally help the water molecules bond even more. This will keep the roaches floating. However, if you manage to bush them in, salty water will drain the roach’s cells and they can die from dehydration.
Heating water before drowning them in it will help in breaking its molecule’s binding force. This will allow them to sink with much ease. Roaches cannot drink hot water and this makes it easy to kill them when compared to cold water.
If salty water is all you can find, then boil it. Boiling helps in breaking its surface tension. It will also improve the molecule’s mobility. If this happens, roaches will easily drown in it. Roaches hold their breath for survival but they can only do so in distilled water at room temperature.