Can You Kill a Spider With Only Water? Find Out Now

by Derrick | Last Updated: April 4, 2022

Spiders can be terrifying –especially if you have arachnophobia– so it’s understandable to want to rid spiders from your home. Many people just freak out and clobber spiders with an object, yet you might think about using a less violent, cleaner method to eliminate them, like water. But is it possible to kill a spider with only water?

You can kill a spider with only water by submerging it and providing no way out. However, spiders have low metabolic rates and oxygen consumption, which can cause them to stay alive for up to 40 hours even while submerged in water.

This article discusses how to best kill a spider with water, the alternatives, and what you should do if you spot one in your home in greater detail. Read on to find out more.

Drowning a Spider

According to National Geographic, there are over 45,000 species of spiders around the globe. Primarily three types of spiders exist in these species: Land-based spiders, semi-aquatic spiders, and aquatic spiders.

Land-based spiders drown relatively quickly when fully submerged in water. By contrast, the semiaquatic and aquatic variants are much more resilient due to some adaptations to the water-based lifestyle and will struggle for longer.

An example of an adaptation permitting aquatic spiders to stay in water for longer is hydrophobic (water repellent) hairs on the body. These hairs perform several essential functions, including: 

  • Allowing the spider to float and walk on water using surface tension 
  • Trapping air which the spider can use to breathe underwater (for a limited time)

Even so, semi-aquatic and aquatic spiders must come up to the surface for air from time to time, and if they’re not allowed to do so, they inevitably run out of oxygen and drown. Therefore, if you happen to trap a spider in a water container (such as a glass or a jar) and submerge it fully, death is inevitable for the little creature.

Although, it’s unlikely that you’ll encounter aquatic spiders since only a fraction of these species appear in and around urbanized areas. More commonly, land-based types tend to show up in these locations.

Washing Them Down the Drain

Let’s also quickly touch on what would happen if you were to flush a spider down the drain. If the spider manages to grab on to something and crawl back up or escape through another pipe, it’ll live.

If it gets taken all the way into the sewers, though, the chances of it surviving are slim to none. The spider will most likely drown due to sewer waters being even thicker and harder to swim in than regular water. 

Aquatic spiders such as the diving bell spider are more likely to survive due to adaptations that allow them to build underwater webs that can be filled with air. They only need to come up for air once a day.

How To Deal With a Spider in Your Home

Even though submersion in water will kill a spider, it’s probably not something you should do. Not only would you have to capture the spider in a container and fill the container with water while making sure the spider doesn’t escape, but it might also take hours for the spider to perish. It’s impractical and, in some sense of the word, cruel, as the spider would have to struggle until it dies. 

Instead, here are some more humane ways to handle a spider in your home:

Relocate the Spider

This is the best way you can handle the situation. Most of the spiders you’re likely to find in a house aren’t dangerous. They might look scary, but they usually have no reason to attack you. Spiders that have bred and hatched offspring may act aggressively if they consider you a threat, but that’s a scenario that should be dealt with in an entirely different way. Otherwise, spiders attempt to stay away of their own accord. 

Common spider stings are also not as dangerous as you might think. Very few species of spiders have venom potent enough to cause harm to a human. However, it’s important to be aware of those that do since you want to be careful around them. Brown Recluse and Black Widow spiders are famous examples of venomous spiders that can occasionally sneak into homes in the U.S.

Spiders can even help reduce the number of pesky insects and critters such as mosquitos in the area.

To relocate a spider, try capturing it in a container and releasing it some distance from your house, such as in the front or back yard.

Exterminate the Spider

I don’t personally recommend this unless you’re dealing with an infestation. In that scenario, it’s probably best to call pest control or professional exterminators.

Here are some ways you can exterminate spiders quickly:

  • Strike them with a blunt object: Hitting them with a blunt object is the most straightforward approach but not necessarily the best. Far from it, actually. Especially if the spider is pregnant, you could end up with a floor full of baby spiders crawling everywhere. That’s the stuff of nightmares, even for the most fearless of us. In any case, it’s going to be messy and violent. Best to avoid if you’re squeamish.
  • Use an insect spray: Insect sprays are readily available in online and offline marketplaces. They are effective, convenient, and won’t make a mess
  • Vacuum the spider up: Vacuuming is especially effective if you are dealing with multiple spiders or a minor spider infestation that you feel you could manage yourself. This requires you to get close to them and dispose of a bag filled with spiders, so be mentally prepared.


Spiders are, without a doubt, some of the most intimidating insects you can come across. You can kill a spider by trapping it in water, but it’s important to remember that spiders are usually harmless and should be relocated if found inside your home. Other ways of killing spiders include hitting them with brute force, using an insect spray on them, or removing them with a vacuum cleaner.