Does bleach kill germs? Yes, but you need to let it sit for 10 minutes

insider@insider.com (Sara Lindberg)
You can mix one cup of bleach with five gallons of water in a bucket to create a solution that will disinfect surfaces.

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  • The active ingredient in bleach is sodium hypochlorite, which can effectively kill germs like viruses, bacteria, and fungi. 
  • Since the influenza virus can live on surfaces for 24 to 48 hours, and the virus responsible for COVID-19 can live for up to 72 hours, it's important to use a disinfectant like bleach on frequently-touched surfaces.
  • To kill germs, mix 1 cup of bleach with 5 gallons of water and scrub it onto the surface you want to disinfect, letting it air dry for 10 minutes before you wipe it off. 
  • This article was medically reviewed by Tania Elliott, MD, who specializes in infectious diseases related to allergies and immunology for internal medicine at NYU Langone Health 
  • Visit Insider's homepage for more stories.

Bleach tops the list of household products you can use to kill germs. Typically known for its ability to get your whites "whiter" or sterilize your toilet bowl, many people are now reaching for a bottle of bleach to help kill germs and viruses on a wide variety of household surfaces. 

With that said, there are some guidelines when using this chemical to clean surfaces. Here's what you need to know about using bleach to kill germs. 

Bleach kills germs, including viruses and bacteria

The active ingredient in bleach, sodium hypochlorite, is effective in killing bacteria, fungi, and viruses, including influenza virus, staphylococcus (which leads to staph infections), streptococcus (most known for causing strep throat), salmonella (which leads to diarrhea, fever, and stomach cramps), and even the common cold, according to David Nazarian, MD, a board-certified primary care physician at Concierge MD. 

"You can use bleach as a surface disinfectant to destroy the protein structure of organisms such as viruses and bacteria," says Nazarian.

According to Viseslav Tonkovic-Capin, MD, a double board-certified dermatologist and the editor of DermBoard, this is because sodium hypochlorite oxidizes or burns the protective membranes of bacteria and the protein shell of viruses, leaving them vulnerable to destruction. 

Cleaning hard surfaces with bleach can prevent the spread of infections, Nazarian says. This is because bleach can effectively eliminate pathogens that live on surfaces and  can be transferred by hand to your mouth or nose and gain access to your system. 

For example, influenza can live on surfaces for 24 to 48 hours and COVID-19 can survive for up to 72 hours, depending on the surface, says Nazarian. Bleach drastically decreases this possibility.

The Environmental Protection Agency (EPA) has stated that sodium hypochlorite is effective against SARS-CoV-2, the cause of COVID-19. But after wiping nonporous surfaces, you must be sure to let the bleach sit on the surface for 10 minutes or more to assure proper disinfection.

How to use bleach to kill germs

Before using bleach, make sure the surface you are cleaning can handle a disinfectant. For example, bleach should not be used on wood floors or painted surfaces. But bleach is fine to use on most kitchen counters, bathroom sinks, or even other frequently-touched surfaces such as door handles and faucets. 

To sanitize surfaces with unscented household bleach, the CDC recommends mixing together one cup of bleach and five gallons of water. Here's how to do it: 

1. Mix the one cup bleach and five gallons of water together in a bucket.

2. Use the solution to scrub rough surfaces with a stiff brush. 

3. Air dry for at least 10 minutes. Since this can result in toxic fumes, be aware of signs of over-exposure such as blurred vision, difficulty breathing, and headaches. If you experience this, the CDC says to seek medical attention.

For a smaller batch of cleaner, the CDC recommends using four teaspoons of bleach with one quart of water and following the same instructions.

To sanitize fabric with bleach, add bleach to the wash cycle, then dry on high heat. This is effective for whites. As to the amount of bleach, the Clorox website recommends 3/4 cup of bleach for a regular size load. If the load is extra-large or heavily soiled, add an extra 1 1/4 cup. 

Bleach should not be applied directly to skin since it may cause irritation. If you get it directly on your skin, wash with gentle soap and water. 

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