Here’s the definitive science-based answer:
Coffee makers can kill most bacteria as they become inactive at temperatures above 145° F (65° C), according to the World Health Organization (WHO).
However, researchers from the Scientific Reports journal have found between 35-67 types of bacteria in the leftover coffee from the waste tray.
This implies that certain parts of coffee machines (e.g. the coffee waste tray) can be a great breeding ground for microorganisms.
The same researchers also found that no matter what kind of coffee you make or how frequently you brew coffee through your coffee maker, bacteria were still present.
Thankfully though, you can greatly reduce the number of bacteria in your coffee machine by regularly rinsing its capsule container.
If you make it a habit to wash your coffee maker thoroughly every week, using warm water and soap.
Trust me, this will make the coffee maker that much cleaner and as a result, you’ll be drinking coffee that isn’t jam-packed with bacteria.
Coffee Makers 101
A coffee maker is a cooking appliance that’s created for the sole purpose of brewing coffee.
Believe it or not, but coffee makers have been around for a long time i.e. hundreds of years.
Interestingly enough, the primary concept of coffee makers has always been the same.
- Also read: Which coffee maker is easiest to clean?
You just pour hot water over coffee grounds so that the infusion process takes place (the good stuff gets extracted from the coffee grounds).
Then you trap the grounds (e.g. by a filter or tea strainer) and voila – you have a cup of coffee that’s ready for drinking.
And as you might imagine, there are different types of coffee makers out there – here they are:
- Espresso machines
- Vacuum brewers
- Single-serve coffee makers
- Moka pots
- Electric drip coffee makers
- Pour-over coffee makers
These days, pod machines are quite popular.
They rely on capsules with coffee inside (instead of manually putting coffee grounds in the machine) that are simple and easy to use.
And that’s where their strength lies in – the convenience they offer.
Coffee Might Contain Less Harmful Bacteria Types
While coffee itself doesn’t and shouldn’t contain any (harmful) bacteria, it’s worth noting that certain microorganisms are involved in the fermentation process of coffee.
Several bacteria such as yeasts, fungi and mostly lactic acid are part of coffee fermentation.
As for fermentation itself, it’s been primarily used due to its beneficial effect on coffee flavor.
However, a good number of experts these days suggest that mechanically washed coffee (that doesn’t involve any fermentation) can be just as effective in preserving the quality of coffee beans.
But hey, coffee can actually have bacteria-stopping properties:
Coffee has been shown to prevent the growth of bacteria that cause food poisoning, according to findings of microbiologists from the American Society of Microbiolgy.
Basically, they examined the effect of a coffee extract on the growth of particular kinds of bacteria that cause food poisoning (e.g. Salmonella).
Eventually, they concluded that coffee has the potential to halt the growth of certain, rather unpleasant bacteria.
Bacteria such as Escherichia coli (O157: H7), Staphylococcus aureus and Salmonella!
I’d also want to point something out – don’t mistake any bacteria that can be found in a coffee maker with the bacteria that occurs during the natural coffee fermentation process.
Truth be told, coffee is actually good for the bacteria in your gut since the microbes in your stomach ferment fiber from the coffee that you consume.
And as you might know, fiber is good for your gut health and the digestive system in general.
Bacteria Can Also Grow in a Keurig Machine
Bacteria can most definitely grow in every coffee machine, including the quite popular Keurig coffee maker .
I already mentioned that Spanish researchers have stumbled upon up to 67 forms of bacteria.
They did so by taking microbiological samples from the leftover coffee in the tray of nine separate Nespresso machines.
And while that’s pretty nasty, your Keurig machine isn’t bulletproof when it comes to any potential bacterial and germ growth.
In 2015, a CBS reporter sent some samples from the cup that stores the grounds in just about every coffee maker out there, only to be shocked by the microbiological results.
The microbiologist who conducted the tests discovered all kinds of bacteria, including:
- The notorious E. coli
Don’t think that the water reservoir is any less contaminated though since the same test revealed a whopping 100,000 bacterial colony in one of the machines tested.
Although these germs might not affect you, you have to remember that bacteria like E. coli can potentially cause gastrointestinal problems.
They could very well upset your stomach, especially if your immune system isn’t particularly strong.
This is How to Disinfect Your Keurig Coffee Maker
Here are 3 very simple things that you can do to properly maintain your Keurig (or any other coffee maker for that matter) and keep it nice and clean:
- Dry out your coffee machine after each use – Do this by lifting the handle and don’t forget to wipe off any moisture from the water reservoir lid (you can do that for the rest of the machine too).
- Clean your machine on a regular basis – Use water and even soap to clean some of the dirtier parts of your coffee maker, such as the leftover tray, water reservoir, filters etc.
- Run vinegar through the machine – You can put some vinegar in the machine and run it every month or so, to keep it disinfected. In case you didn’t know, vinegar is considered a safe and natural alternative to bleach.
Generally, if you keep your coffee maker clean by maintaining it on a regular basis you’ll have a better-tasting cup of coffee.
Above all though, keeping your brewer clean will also prevent the growth of mold and bacteria and prolong the life of the machine itself.
Coffee Makers Don’t Boil the Water When Brewing
And there’s a good reason for that as the optimal temperature for brewing coffee is 195° F to 205° F, while the boiling point of water is 212° F (or 100° C).
The aforementioned temperature range ensures that the flavor of the coffee will be properly extracted, thus giving you a tasty cup of coffee.
On the other hand, boiling coffee is a big no-no as the boiling water pretty much burns the coffee grounds.
This translates into a bitter and burned taste of the coffee and since no one sane enough wants that, coffee machines don’t actually boil the water.
As you can see, this could be a problem if you’re worried about the quality of the water that you’re using for brewing coffee.
It’s well known that boiling water kills any bacteria and viruses that can be found in the water, thus purifying it.
However, something that boiling doesn’t do is get rid of the odor or taste of the water.
So if your water had a funny taste prior to boiling it, I’ll have to disappoint you – it’ll probably taste just as bad after it’s been boiled!
Coffee Makers Can’t Fully Sterilize Water
All that a coffee maker does with the water that you’re putting into the water reservoir is simply heating it, but not enough to make it boil.
As already mentioned, that’s because boiling ruins the taste of the coffee and because the optimal brewing temperature (195-205° F) is lower than the boiling point of water (212° F).
Many people assume that the water that comes out of the coffee machine has got to be pure and clean since it’s hot.
Unfortunately, that’s nothing but a general misconception and you shouldn’t count on your coffee maker to purify the water for you if you have the slightest doubt about its quality.
If your tap water is that bad or you’re afraid that it contains too many minerals or even chemicals (Lord knows what they put into it these days), there are other ways for cleansing it.
You can get yourself a water filter or alternatively, you can just buy some bottled water and use it for making coffee – it’s up to you really.
A Coffee Maker Can Get Moldy
Your coffee maker can get rather moldy as mold spores tend to really like moist places.
That’s exactly what the inside of your coffee machine is.
And when you add the fact that the water only gets heated, but doesn’t reach boiling point, you have the perfect conditions for the growth of mold and germs.
To prove that mold and coffee machines go hand in hand, there’s a relevant study, courtesy of NSF International that examined the top germiest places in our homes and come to intriguing conclusions.
Researchers found that coffee makers are among the most bacteria and mold-friendly items in a home.
Do This to Get Mold Out of a Coffee Maker
Try carefully washing every detachable part of your coffee machine, like the tray, filters etc.
Scrub each one of them using dish detergent and also don’t forget to clean the outside of the machine as well, since there could be mold spores and dirt in there as well.
And if you want to takes things to the next level i.e. make your coffee maker as clean as possible, do this to clean its “intestines”, so to speak:
- Mix some water with vinegar (even parts)
- Pour the mix into the water reservoir of the coffee machine
- Push the start button to start brewing
- Once done, let the mixture stay at the pot for 10 mins
- Throw the water-finger mix out
- Add some fresh water into the water tank
- Start brewing
- Rinse and repeat a few times to make sure that the vinegar is out of the system of your coffee maker
This is one cheap and easy-to-apply method for cleaning the entire system of the machine.
It’s also a superb way to make the most amazing coffee to please your java palate.
Quite frankly, coffee makers not only don’t kill any bacteria or germs, but they’re actually one of the most favorable places for the growth of bacteria, mold etc.
And the bacteria will grow, no matter where you put your coffee machine in the kitchen.
Still, the good news is that properly cleaning your brewer can prevent any potential germination of your favorite coffee machine.
This means washing every part of the machine that can be removed and thoroughly cleaning the entire unit.
Do you have a favorite technique for cleaning your coffee maker btw?
Let me know in the comment section below!
Did somebody say coffee? Two shots of espresso for me, thanks. Oh, nevermind – I’m Simon, nice to e-meet you, dear CoffeeLifior! I like to write, drink coffee and I believe in Jesus. Highly-caffeinated drinks are my thing, but you can occasionally see me sip on decaf (my wife never finishes her coffee). Speaking of which, I’m off to grab another cup of caffeinated goodness now, laters!
Last update on 2022-09-03 / Affiliate links / Images from Amazon Product Advertising API