How To Reheat Coffee in Coffee Maker: Step-by-Step Guide

Wondering how to reheat coffee in coffee maker? Check out our guide to find out!

Reheat coffee in coffee maker
Reheating coffee in your coffee maker is not a good idea

I’ll admit it – even though I love the taste of fresh coffee, I still drink leftover coffee all the time. Why dump half a pot of coffee just because you brewed it a few hours ago? Sometimes I’m just lazy, and sometimes I’m in a hurry and don’t want to grind a fresh batch of beans. Either way, knowing how to reheat your coffee to taste as good as possible is important.

So, how do you reheat coffee in a coffee maker? The best advice is that reheating coffee in your coffee maker is not a good idea. If your coffee has been sitting out at room temperature for a few hours, it makes the perfect breeding ground for harmful bacteria, so you need to make sure it’s reheated correctly.

Your coffee maker’s heating plate will not bring the coffee back to a safe temperature, so you’ll need to try a different method. Let’s take a look at some of the best ways to reheat your coffee.

The Microwave Method

The microwave method is the way to go when you’re in a hurry. The only problem with using the microwave is that it tends to break down the aromas in your coffee. Aromas are responsible for most of the flavor, so you might end up with a bland cup of coffee.

This is fine if you’re in a hurry, but it’s not ideal.

Step 1: Set the microwave to medium heat.

Step 2: Pour your coffee into a microwave-safe container. This could be a mug or microwave-safe jug.

Step 3: Heat your coffee for about a minute, test the temperature, and reheat for an additional 30 seconds if it’s not steaming hot.

Step 4: Pour into a fresh mug and enjoy!

The Stovetop Method

Coffee on the stove
Reheating coffee on your stovetop is the best method to reheat coffee

The stovetop reheating method is a great choice. If you’ve ever made coffee using the drip brewing method, add a little water and warm it up on the stove for a delicious-tasting cup. Check out our Chemex vs. drip coffee review to learn more!

Step 1: Pour your coffee into a small saucepan and a little fresh water. You’ll lose some water as the coffee simmers and steam rises, so adding water will make sure it doesn’t become too strong.

Step 2: Warm it up on medium heat until the coffee starts to simmer. Don’t use full heat; you’ll burn the coffee.

Step 3: Take the coffee off the stove when it starts to gently simmer. If you go to a rolling boil, you might change the flavor of the coffee or make it too hot to drink.

Step 4: Pour into your mug and enjoy!

Why You Can’t Reheat Coffee In A Coffee Maker

There’s one simple reason why you can’t reheat coffee in a coffee maker: the warmer plate doesn’t get hot enough. Whether you’re using a Mr. Coffee or a different kind of coffee pot, your coffee machine probably has a “keep warm” function. This means that the bottom of the coffee maker will heat up during the brewing process.

If you leave your coffee in the pot, it stays warm for 2-4 hours. This heated area is known as a warmer plate. Warmer plates don’t add heat to your coffee; they just help the liquid in the pot stay at a drinkable temperature.

If you have cold coffee in the pot and turn the coffee maker back on, the warmer plate will start heating up. Your old coffee might even get warm. But because it’s just a warmer plate, your coffee won’t get hot enough to kill bacteria.

The Problem With Room Temperature Coffee

Lukewarm coffee doesn’t taste very good, but that’s not the only reason not to do this. Drinking coffee that’s only a few degrees above room temperature can be dangerous. Bacteria can grow in any environment colder than 165 degrees and warmer than 42 degrees.

Health safety officials call this the “danger zone.” If your coffee has been sitting out at room temperature for more than 4 hours, it’s in the danger zone. You should probably throw it out and make a fresh batch.

If your coffee hasn’t been sitting out for very long but has started to cool down, you need to heat it back up to a safe temperature. Your coffee maker’s warmer plate simply can’t do the job.

What Not To Do When You’re Reheating Coffee

Reheating coffee is all about preserving the flavor and making sure that your leftover drink is safe to consume. While you’re experimenting in the kitchen, there are a few methods that you need to avoid.

  • Don’t leave your coffee out overnight. Like any food item, it could develop bacteria and become unsafe to drink.
  • Don’t leave your coffee in the “keep warm setting” unless you plan to drink it in the next few hours. The longer your coffee sits on the warmer plate, the more condensed the flavor will become.
  • Don’t disable your coffee maker’s automatic shutoff feature. If you forget to turn it off yourself, you could end up with burnt coffee all over the bottom of your glass carafe.
  • Don’t pour old coffee into your coffee maker’s water chamber. Coffee makers aren’t easy to clean; if you run coffee through the water chamber, the taste of old coffee might never go away.
  • Don’t put the glass carafe in the microwave. Coffee pots are not designed to be microwaved, so pour your coffee into a mug instead. You should also never put the carafe on the stove.

Instead of trying any of these dangerous or damaging methods, reheat your coffee with these simple rules:

  • Do store leftover coffee in the fridge so it doesn’t develop bacteria.
  • Do reheat coffee in a microwave-safe cup if you’re in a hurry.
  • Do make a fresh pot for the most delicious taste.

Why Fresh Is Always Best

There's nothing better than the smell of fresh-brewed coffee
Fresh-brewed coffee tastes better

You’ve probably heard coffee snobs say that fresh is always best. I’m not a coffee specialist, but I must admit that a fresh-brewed pot tastes better. Obviously, fresh food of any sort is more delicious, but the flavor of coffee can degrade quite a bit over time.

Coffee is composed of delicate compounds that contribute to flavor and smell. These compounds are unstable and will break down if exposed to air or water. Air and water are the two most important ingredients in the coffee brewing process.

As soon as you grind your beans, they start to change. Once you’ve poured hot water over them, the chemical reaction hits full swing.

A brewed cup of coffee is essentially a mixture of water and aromatic oils that have been extracted from the coffee beans. If you drink the coffee right away, the balance of flavor is amazing. But the longer you let that pot of coffee sit, the more the oils will break down and sink to the bottom.

Adding heat to the mix will also change the flavor components in your coffee. Those oils can burn, and burnt coffee tastes bitter and acidic. That’s why you shouldn’t leave the coffee on the warmer plate for hours.

FAQs About How To Reheat Coffee In Coffee Maker

Can you still drink old coffee?

Yes, you can absolutely drink it, and it might taste fine. But if you want the best taste, you should use fresh beans and immediately drink your coffee.

How long is old coffee still safe to drink?

Coffee left at room temperature is safe for up to 4 hours after it comes off the heat. Refrigerated coffee can be safe to drink for up to 2 weeks. When in doubt, make fresh coffee instead.

Why is my coffee maker brewing cold coffee?

You might need to clean your coffee machine if it isn’t working well. Run a cycle with nothing but hot water. Then, combine water with a few tablespoons of vinegar and run it again.
Go through one more cycle of pure water to finish cleaning your machine.

Why is my coffee maker turning off randomly?

Many coffee makers have an automatic shutoff feature. This safety feature will turn off the coffee pot after 2 to 4 hours. Depending on the coffee maker, you might be able to change the shutoff time.

Looking for more? Check out our guide to the best coffee for drip filter coffee makers!


  • Aisling O'Connor

    Aisling is an Irish food and drinks writer and journalist fueled by coffee and herbal tea. She followed up her journalism degree with nutrition studies. Find Aisling on LinkedIn.