Are mold and bacteria growing inside my coffee maker?

by Lori
(Georgetown, TX)

Use white vinegar to kill mold and bacteria in your coffee brewer.

Use white vinegar to kill mold and bacteria in your coffee brewer.


I was talking with someone at work yesterday who said she had watched a segment on her local news station about how mold and bacteria grow inside coffee makers.

Is this true? If so, how can I make sure my coffee machine is mold and germ free?

The idea of us drinking mold and germs with our coffee freaks me out!



Lori, hi

I have heard the same myself. And it makes sense if you think about it. The inside of a coffee maker, or a home espresso machine, is dark, damp and often warm. In other words, ideal growing conditions for both mold and bacteria.

You might think the hot water alone would keep the inner workings of your brewer clean. Not so. The water isn’t hot enough. To sterilize your brewer the water would need to be at boiling point, and be in contact with the inside of the brewer for a minute or two. This doesn’t happen.

The problem is probably exacerbated inside modern, single serve brewers which include small water pumps which are constantly primed. This means there is water in the machines even between brewings.

And yes, it's a pretty gross thought to imagine clumps of mold and bacteria growing away and waiting to be flushed into your next cup of coffee.

How do you deal with this?

Vinegar to the rescue!

Yes, household vinegar kills germs and molds.

Here is what you do:

1. Fill your brewer’s water reservoir with 50% white vinegar and 50% water.

2. Run the mixture through your brewer (without using any coffee, of course).

3. Halt the brew process half way through, so there is plenty of vinegar mix inside the machine.

4. Leave it to sit for 30-60 minutes so the vinegar can do its work.

5. Complete the cycle.

6. Rinse the brewer’s insides by filling the reservoir with fresh water and then running it through the machine a few times.

And that’s it. You now have a super-clean and mold and bacterial-free coffee maker!

I hope this helps.


Additional information that might interest you:

The 67 types of bacteria growing in your brewer’s drip tray

Coffee from our new coffee maker tastes bad.

The plastic taste in new coffee makers – Just a bad taste, or toxic too?

Is There an Automatic Drip Coffee Maker with no plastic parts?

Comments for Are mold and bacteria growing inside my coffee maker?

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Oct 13, 2015
Coffee moldy taste
by: Anonymous

Ran 1/2 cup vinegar through coffee pot and coffee still tastes like mold. The filter and coffee was left in it for a month. Vinegar did not work. How about bleach?

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