Hydrogen Peroxide Experiments




Does 3% hydrogen peroxide kill germs?


Answer: Yes! It does better job killing bacteria in my experiments than most other products. It probably doesn't kill all types of bacteria, and I can't test for viruses. 






Experiment Details


In this experiment, I compared the bacteria killing power of regular 3% hydrogen peroxide (in the brown bottle from the pharmacy section at Walmart), Essential Oxygen Food Grade 3% hydrogen peroxide, and pure white vinegar. This is the basic procedure that I always use to test cleaning products on the countertop. First, I used masking tape to section off squares on my kitchen countertop and labeled them according to what I would be testing. I made sure that my countertop was very clean to start with, of course.






Next I made germy water. To do this I mixed a small scoop of mud from our back yard into purified water. Then I poured the muddy water through a paper towel to filter out the chunks. I was left with very dirty water which contains lots of bacteria. For some experiments, I also scraped bacteria off of an already grown agar plate from a previous experiment and mixed those germs in. This way my "germ water" had lots of bacteria in it.








I put 1mL of germ water onto each square with the exception of the "clean" control square using these 1mL syringes.







I rubbed the germ water around the square with my gloved finger. Then I let the squares dry completely which took 2-3 hours.





Once the squares were dry, I put .5mL of each cleaning product onto its respective square. For this experiment, I used 5 mL of 3% hydrogen peroxide, 5mL of Essential Oxygen 3% hydrogen peroxide, .5mL white vinegar, and .5mL water on the respective squares.





I rubbed the cleaning product around to completely cover the square using a clean gloved finger. I went over the square a few times to make sure that the cleaning product completely covered it. Then I set a timer and let the cleaning product sit on its square for 5 minutes.





After the allotted time, I used a sterile swab to swab the square. Most squares were still wet after 5 minutes. I rubbed all over the square but I did not touch the tape (just in case the tape held onto bacteria and interfered with the experiment).



Then I scribbled all over an agar plate with the swab.



If you want to do these experiments yourself, I used these agar plates available on amazon. They come with the sterile swabs.





The plates were incubated for 24-48 hours in my homemade incubator consisting of a plastic box and a heat lamp. The temperature was about 90 degrees F. Any bacteria present on the plate will grow and multiply. After about 24 hours you can see colonies (or piles) of bacteria on the plates. It is important to remember that viruses do not grow on these plates. Just bacteria and some fungus. Also not all types of bacteria grow on these plates. So, a clean looking plate does not necessarily mean that there were no microorganisms whatsoever were present. It just means that nothing that could grow on the agar plate was present. However, this is still a very valuable information for comparing different cleaning products.








Results










As you can see, both the regular 3% hydrogen peroxide and the Essential Oxygen 3% hydrogen peroxide did a fabulous job killing bacteria. Pure white vinegar killed some, but not as much as the 3% hydrogen peroxide. I use 3% hydrogen peroxide as a control in most of my experiments.

I cannot guarantee that 3% hydrogen peroxide will kill ALL bad bacteria and viruses. There are probably plenty of germs that the 3% hydrogen peroxide won't kill.  Here is a research paper stating that 3% hydrogen peroxide is good for killing salmonella and e.coli. However, other research shows that it is NOT good for killing norovirus. (That is why I recommend keeping chlorine bleach or the Clorox Hydrogen Peroxide products on hand for emergencies when someone is throwing up. Those products have been tested and proven to kill norovirus surrogates.) 



I also found these travel sized bottles of 3% hydrogen peroxide. I bought one and tested it. It worked great killing bacteria. You can refill them. 

Does 3% hydrogen peroxide disinfect the kitchen sink?

Answer: Yes! It does better job than most other products killing bacteria in the kitchen sink. 



Experiment Details

Just because a cleaner doesn't appear to do much in my experiments, doesn't mean that they don't do what the label says. Most of them say that they can only be used on already clean surfaces. Some of my countertop experiments have so much bacteria that it might not be a true reflection of what is going on in your house. So, I also like to test products in a real-life situation. Any product that we depend on to disinfect, should be able to disinfect the kitchen sink. 

Here I tested pure white vinegar and hydrogen peroxide on my kitchen sink. I use my neighbors' sinks too. I have a 2 sided stainless steel sink. First, I rinse the sink really well to make sure it looks clean. Then I swabbed the sink and rubbed the swab on an agar plate to see how much bacteria was in the sink. Then I sprayed 30 sprays of 3% hydrogen peroxide all over one side and let it sit for 5 minutes. I did not wipe at all. Then I swabbed that side. Then I sprayed 30 sprays of pure white vinegar all around on the other side and let that sit for 5 minutes. I swabbed that side and the plates were incubated for 48 hours in my warm incubator. 
 




As you can see, the 3% hydrogen peroxide did a great job killing germs in the sinks. The pure white vinegar killed some germs but not as many as 3% hydrogen peroxide. 


Do I have to use so much hydrogen peroxide?

Answer: Yes, the surface needs to be fully covered with any disinfectant to actually kill the germs. 


Experiment Details

I decided to compare spraying one side of the sink with 30 sprays of 3% hydrogen peroxide and the other side with just 10 sprays of 3% hydrogen peroxide. I let them sit for 5 minutes and swabbed.







As you can see, the 10 sprays did just as well as the 30 sprays. However, the hydrogen peroxide will only kill the germs where it touches. So, the sink (or whatever you are cleaning) needs to be fully covered. When I swab the sink, I am essentially spreading the hydrogen peroxide around. So, if there was a spot that was missed when I sprayed, it would possibly get covered with hydrogen peroxide when I move the swab. So, to sum up, 3% hydrogen peroxide is my favorite disinfectant for the kitchen sink. Use plenty to cover the sink and then don't wipe it off, just let it sit. Wipe it off the surrounding countertop, though, so it doesn't fade.

How fast does hydrogen peroxide work?

Answer: I'm not certain yet. I leave it on most surfaces for 1-5 minutes and then wipe it off. 


Experiment Details

I have been using regular 3% hydrogen peroxide for my regular household cleaning of countertops and toilets for a year now ever since I discovered how well it kills bacteria in my experiments. However, I've always tested all my cleaning products for 5 minutes. However, when I use it, I often spray it on and wipe it off pretty fast. So, I decided to test how long it takes hydrogen peroxide to work. I did the experiment on the countertop just like I always do. I put .5mL of 3% hydrogen peroxide onto each dirty countertop square. Then I let them sit for 5 minutes, 1 minute, or about 10 seconds. I put the hydrogen peroxide on the square, spread it around, and then set the timer for 1 minute and 5 minutes. For the "10 second" square, I spread the hydrogen peroxide around and immediately swabbed. That all might have taken closer to 20 seconds but I did it as fast as I could.




It certainly seems like the hydrogen peroxide works really fast! However, the truth is, the hydrogen peroxide is still with the bacteria after I swab it so I can't be sure if the bacteria dies immediately or sometime later. If you watch the beginning of this video that I made, you can see how hydrogen peroxide starts bubbling immediately upon contacting bacteria. That leads me to believe that it works pretty fast. However, I decided to do a sink experiment where I spray the hydrogen peroxide on and immediately wipe it off. 

Can I spray hydrogen peroxide on the sink and immediately wipe it off?

Answer: No, it needs to sit a while. 

In this experiment, I used my neighbor's sink. I washed one side for 1 minute with a wet washcloth and then swabbed it. I sprayed the other side with 10 sprays of 3% hydrogen peroxide, washed it with a wet washcloth for 1 minute, and then swabbed it. 









As you can see in both of these experiments, spraying with 10 sprays of hydrogen peroxide and then immediately wiping was NOT nearly as effective as letting the hydrogen peroxide sit for 5 minutes. I was very surprised. I guess most of the hydrogen peroxide was absorbed into the already wet washcloth. I need to keep testing this to see if the germs are dead if I wipe the hydrogen peroxide off after the 5 minute time period. Until then, I recommend letting 3% hydrogen peroxide sit on surfaces that you want to disinfect for 1-5 minutes. 

How long is a bottle of 3% hydrogen peroxide good?


Answer: At least a month if you keep the cap on tightly and keep it in its original brown bottle. 





Experiment Details

Hydrogen peroxide is relatively unstable. So, it is not a good idea to use really old bottles of hydrogen peroxide. However, the 3% hydrogen peroxide sold at the store (which I use) is STABILIZED. They have added something to it to make it more stable. I've ask the hydrogen peroxide companies what this "stabilizer" is but they won't give me any information. I hope and assume that the stabilizer isn't too bad since the product is approved for use directly on wounds and as a mouth rinse. 

I decided to test a bottle of hydrogen peroxide that was opened for a month. I had taken some out and used it a few times during the month, but I kept the lid on tightly the rest of the time. I did the same countertop experiment that I always do. I made germ water with dirt from the back yard and bacteria scraped from a previous days "dirty hands" plate. I put 1mL of germ water onto each square on my countertop. I rubbed the germ water all around the squares and let them dry. Then I added .5 mL of each product onto the appropriate square. I spread them around to completely cover the square and set a timer for 5 minutes. After 5 minutes, I swabbed each square and rubbed the swabs onto an agar plate. The plates were incubated for 24 hours in my warm incubator. 





As you can see, the 1 month old bottles of hydrogen peroxide all did great! In this experiment, I had added a few drops of Thieves and Lavender oils to bottles of hydrogen peroxide. The addition of the Thieves and Lavender did not appear to hurt the ability of the hydrogen peroxide to kill germs. 




I also tested a bottle of Essential Oxygen is a food grade 3% hydrogen peroxide that had been opened AT LEAST 6 months. I had kept the cap on tightly but I had used it a few times. I tested it in a countertop experiment.






It still did really well killing bacteria after 6 months.



Is 3% hydrogen peroxide dangerous to people?



 Hydrogen peroxide is not a foreign chemical to your body. Your body actually produces hydrogen peroxide to help kill germs. However, the hydrogen peroxide your body produces is stored securely in vesicles. It is not just floating around. So, will a little hydrogen peroxide penetrating your skin while you clean hurt you? I don't know for sure. The 3% hydrogen peroxide bottle says that it is for wound cleaning and mouthwash. I am hoping that since it is okay to put on wounds and in your mouth, that cleaning with it wouldn't harm you. 

3% hydrogen peroxide is not sold to be a cleaning product. It is a very strong germ killer, and I would not recommend assuming that it is harmless. Yes, hydrogen peroxide eventually turns to oxygen and water, but before that it produces the hydroxyl free radical which is what does the damage to the germs. The hydroxyl free radical can also damage you. I would not put it on cuts or in your mouth unless your doctor or dentist tells you to. Do not drink it. Do not spray it in your nose. Try not to breath the vapors. I wear gloves when I'm cleaning with it, because it is very drying to the skin. 

A website viewer wrote to me and is certain that at age 24, she completely and permanently lost her sense of smell after using hydrogen peroxide to clean for 1 month. However, she went overboard and coated all the surfaces in her house and furniture with it. I still have a good sense of smell, and I've been cleaning with 3% hydrogen peroxide for 3 years. I spray off my toilets every day with 3% hydrogen peroxide. I clean the bathroom countertops with hydrogen peroxide 2-3 times a week. I spray out the bathtub with hydrogen peroxide once a week. I spray out the kitchen sink with hydrogen peroxide 2-3 times a week. I am not a medical doctor, though. Feel free to ask your doctor if it is safe to clean with hydrogen peroxide. 

Hydrogen peroxide also has stabilizers that may or may not be harmful. Also, there is more expensive "food grade" hydrogen peroxide available. This hydrogen peroxide still has stabilizers but they are approved for use on food and food contact surfaces. So, this one would be a better choice to spray off a baby's high chair tray. The link I have here is for a Essential Oxygen 3% Hydrogen Peroxide3% bottle made by Essential Oxygen. The stabilizer in it is sodium acid pyrophosphate which is low risk according to the Skin Deep Website. The food grade comes as high as 35%. Considering that the 3% burns if I get some on my fingers, I am afraid to have the 35% in my house. If a child accidentally took a sip of the 3% they would throw up. If someone accidentally took a sip of the 35%, they might die. 



Is 3% hydrogen peroxide harmful to household surfaces?

Answer: It is safe on most surfaces for short periods of time. I don't know about granite.


3% hydrogen peroxide can fade countertops and wood or dark floors over time so don't let it sit on those surfaces more than 5 minutes. The gray countertop that I have done a zillion experiments on where I let 3% hydrogen peroxide sit for 5 minutes is NOT faded at all. However, there is an area of the countertop next to the kitchen sink that is faded. It is faded because I spray out the kitchen sink with hydrogen peroxide and let it sit. Some of the mist got on the surrounding countertop and I never wipe it up. After doing that for months, the countertop faded. So, it is okay to let the 3% hydrogen peroxide sit on the sink, bathtub, or shower until it is dry. But wipe it off of other surfaces after 5 minutes so it doesn't fade them. The wood floor around my toilet is also faded. I spray off the toilet every day and some mist falls on that wood floor. It took about a year before the floor started to fade. I've used hydrogen peroxide to clean up dog throw up off the same wood floor. I let it sit for just five minutes and wipe it off. That did not fade the floor at all. 

Can essential oils be added to hydrogen peroxide for cleaning?

Answer: The hydrogen peroxide still kills germs well even with a few drops of oil added. The oils do not mix with hydrogen peroxide. They separate but still make it smell good. 

Many essential oil fans have asked me if a drop of essential oils can be added to the bottle of 3% hydrogen peroxide to make their cleaning smell better. I decided to test it along with the test of how long a bottle of 3% hydrogen peroxide is good. I put about 3 drops of Thieves oil into a new bottle of 3% hydrogen peroxide. I also put about 3 drops of lavender oil into another new bottle of 3% hydrogen peroxide. I also opened a new bottle of hydrogen peroxide, used a little, and put the lid back on. I let these bottles sit for about a month.

Then I did the same experiment that I always do. I made germ water with dirt from the back yard and bacteria scraped from a previous days "dirty hands" plate. I put 1mL of germ water onto each square on my countertop. I rubbed the germ water all around the squares and let them dry. Then I added .5 mL of each product onto the appropriate square. I spread them around to completely cover the square and set a timer for 5 minutes. After 5 minutes, I swabbed each square and rubbed the swabs onto an agar plate. The plates were incubated for 24 hours in my warm incubator.





As you can see, the 1 month old bottles of hydrogen peroxide all did great! The addition of the Thieves and Lavender did not appear to hurt the ability of the hydrogen peroxide to kill germs.




I had also done this experiment a month earlier comparing pure 3% hydrogen peroxide, 3% hydrogen peroxide with a few drops of Thieves oil, and pure Young Living Thieves oil (.5mL of each thing). In this case, the Thieves had only been in the hydrogen peroxide for 18 hours before the experiment. As you can see, the hydrogen peroxide still killed bacteria well even with the Thieves added.




It is important to remember that I kept the caps on tightly the entire time the hydrogen peroxide was stored. So, it might not be good if you leave the cap off all day. I make it a point not to tell people to "mix chemicals". I don't know for sure that no crazy or harmful reaction is taking place between some component of the essential oil and the hydrogen peroxide. However, I didn't die breathing them, and they all still smelled good after a month. So, you can make your own decision about that.


If you would like to suggest an experiment, please post on my facebook page. I also really need to earn money from this website in order to keep doing experiments (agar plates, essential oils, and cleaning products are expensive). If you want to contribute, please use my Amazon affiliate links. Just click on any of my links that go to amazon, and buy whatever you want. You don't have to buy what I recommend or even the product that the link goes to. Here is a link. I'll get a small percentage of the sale and use the money to buy experiment supplies. Thank you.

--Annie Pryor, Ph.D. 

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