Spoiled day-old coffee

Is it OK to drink day-old coffee?

While it’s usually never a coffee-lover’s intent to leave behind coffee in the pot, sometimes life gets in the way. Maybe you brewed more than you needed, or perhaps you forgot to pour your to-go cup for the road on the way to work. You could have even been distracted by the kids, a phone call from the boss, or the dog puking on the rug.

So many morning distractions can interfere with our coffee consumption. There’s that motto of “waste not, want not” though and it begs the question…is it OK do drink day-old coffee?

The good news is yes, it is!

Of course, it does come with a few contingencies which I’ll cover below. In a nutshell, any coffee you’ve brewed and accidentally left behind in your pot can still be consumed for up to 24 hours or in some cases more after brewing. The coffee in question must not have any milk, cream, or other dairy (or even those non-dairy alternatives) in it.

Regardless of dairy or lack thereof, any remaining coffee should be stored in your fridge. Leaving it out for prolonged periods of time exposes it to the potential for mold, something you most certainly don’t want to drink. Those of you in warm climates should be extra vigilant about that though it can happen to any coffee-drinker anywhere.

So, what are the other rules for drinking day-old coffee? I’ll explain them all below so keep reading!

How long does coffee last in all its different forms?

All coffee has a shelf life. And while you might not keel over and die from drinking old coffee, when it’s past its prime, it’s going to leave a bad taste in your mouth, quite literally. It’s helpful to understand how long your coffee lasts in all its forms so you don’t wind up with a less-than-delicious cup, or worse, serve guests something unhospitable.

– Whole beans

The longest-lasting form of coffee is the whole bean. I’ve mentioned it many times here in my other posts that you should ALWAYS buy whole beans. It’s the best way to enjoy your coffee. Get a grinder and grind up only what you need to make the coffee for you or others in your household. It takes seconds to grind up and you WILL notice a wonderful difference in how fresh it tastes.

Ideally, you won’t go bonkers and buy bulk either. Whole beans taste best right after roasting so you want to get them as close to that roasting date as possible. After opening the bag up, store them in an airtight container away from light, though make sure you use it within a month for the ultimate coffee experience.

Again, you’re not going to get sick if you grind up whole beans you’ve stored properly for more than a month. You will just notice they taste less dazzling than they did when you first bought the bag. That’s more incentive to buy it small and buy it often for freshness.

– Ground coffee

I really must insist that you cease and desist with buying pre-ground coffee. Please stop! It tastes so much better when you grind it yourself. But if you’re going to do it anyway, please use them within 2 weeks of opening the bag. Yes, even if you store it properly. I wrote a post about all that which you can check out here!

– Instant coffee

I’ll be the first to admit that I’m not much a fan of instant coffee. Though sometimes, it is an essential tool. It’s better than going without coffee at all. It can be useful during camping trips or power outages. And in some countries, like South Korea, they make handy little satchels of instant coffee that do taste great but are loaded with sugar and powdered creamer.

In any event, when you choose instant coffee, make sure you use it up within 2 weeks from the time you open the jar. Store it well or those crystals clump together and it’s like trying to dig through permafrost!

But what about brewed coffee? Keep reading and I’ll get into all that!

How long does brewed coffee stay fresh?

As I mentioned in the beginning, brewed coffee can be used around 24 hours after it has been brewed as long as there are no dairy products in it. If you accidentally left a mostly-full mug of coffee on your counter in the morning with cream in it, don’t even think about taking a sip of that when you get home. That’s a big no-no unless you want to play diarrhea-roulette.

Even if it’s a cup of black coffee though, that brewed coffee loses its prime flavor after a good 10 to 15 minutes. It falls flat and when you take a sip of that now-cold black coffee you left behind, it will taste like something from a greasy spoon-style diner on the side of a seldom-used state road.

Big coffee purists will tell you that coffee only stays truly fresh for just a few minutes. They’re not wrong. It does lose flavor with every passing moment. Coffee oxidizes when it brews and keeps on oxidizing long after the brewing is done. That’s why you should rise and shine, pour that coffee and enjoy it right away. Life is definitely way too short to suffer through mediocre or bad coffee.

So basically, air is bad for coffee. It’s not going to change it in such a way that it will make you sick (with the exception of perishable dairy items added in left unrefrigerated), but the taste won’t do you any favors.

And yes, there’s more you should know about drinking coffee you’ve left behind at a later time. Read on and you’ll know what to do with it next time it happens to you!

Two more facts on the lifespan of brewed coffee

Let’s say you bolted out the door, completely forgetting to take coffee with you on the road. It’s too late to turn back now and you come home to a midway-full pot of coffee sitting on your hotplate.

Hopefully, you have a coffee machine with an auto-shutoff feature so you’ll only wind up with leftover cold coffee that has lost a lot of flavor and freshness. If not though, that coffee continues to cook on the burner and becomes bitter. The longer it heats, the more horribly bitter it becomes.

And there’s something else… if your machine doesn’t turn off and there isn’t a lot of coffee left, it could burn completely out and leave a sludge of nasty burnt coffee in your pot. You’ll be glad for that though rather than a fire so live and learn, and perhaps invest in a pot that shuts off on its own, or put a note to remind yourself on the front door so you won’t forget!

While drinking cold coffee that has been left out isn’t that good, drinking it too hot isn’t the answer either. You can burn your lips or your tongue and then your taste buds really miss out on the flavor. The key is to pour it and let it get to a warm temperature. Usually about 5 minutes after you pour it is an ideal time to take a sip.

Why does coffee turn bitter?

I touched upon that oxidation process earlier. It keeps happening even after the brewing process. Leaving your coffee out too long allows a reaction with hydrogen and oxygen which raises the coffee’s pH level. This is what gives it a bitter taste. It’s that taste you will get when you find yourself in a waiting room somewhere and are excited that there’s complimentary coffee. You grab a cup and pour yourself some only to take a sip and wonder how long it’s been there because it’s stale as can be.

The same thing will happen in your home if you let your coffee sit in your coffee machine for longer than it should. If you’re unable to drink all of it, put it in a thermos or other airtight container. Then tuck that into your fridge.

But aside from leaving coffee out for too long, it can still take on a bitter taste. Check to see if you’re grinding it to the right size for your brewing method. You don’t want it to brew longer than it should, and you don’t want to leave it. When using a French press, this is an especially important rule to follow for fresh coffee every time.

With the French press, your coffee continues to brew for the duration it’s in the press. It can become disgustingly bitter in only a few minutes. Pour it immediately into your mug and then any other vessel you’ve got to avoid ruining the rest of your French press coffee.

Brewed coffee starts losing the pinnacle of its flavor after 30 minutes or once it has cooled. From there, you need to rescue it if you want to enjoy it later. In about 4 more hours, the oils in the coffee deplete which negatively impacts the taste even further. So, in short, don’t forget about your coffee after brewing it. If you can’t drink it all, save it and store it in the fridge!

Key factors you should consider when checking the freshness of your coffee

Before you go packing that coffee into the fridge that you left behind, there are a couple of factors you need to think about in the name of freshness.

– What’s in that coffee

Let’s say that this morning, you poured your coffee and then added milk to it. Then you spaced and left it there on your kitchen counter all day. Sorry, but you’re going to have to throw it out. As a rule of thumb, coffee with milk in it that is left unrefrigerated for more than 2 hours is not drinkable. Milk requires refrigeration or else it will spoil, so if you’ve forgotten your coffee with milk in it and left it out, it’s a goner.

– Timing of how old your coffee is

With coffee, at 30 minutes past the brewing time, it cools down and loses its flavor. But hit the 4-hour mark and the oils deplete. Your coffee is then more acidic. You can heat it up all you like in the microwave, but it won’t make it taste any better. You’ll just have hot, bitter coffee.

It isn’t dangerous though, so if you are desperate for coffee and have no other means, you can still drink it. It’s just not going to be a very tasty experience.

And in the event you’ve left it out for a day, I urge you to throw it out at once and clean your coffee pot and machine. Day-old coffee has the potential to develop mold. Yuck!

Still keen on drinking that day-old coffee?

Should you not want to listen to my voice of reason and want to avoid wasting that cup of coffee with milk that you left out, you could microwave it. This will kill off some of the bacteria, but there could still be some lingering. Microwaves heat from outside in so there will be random cold spots in the middle. That’s where bacteria can hang out. I strongly advise you to please, please, please, no matter how delicious that first sip was in the morning before you forgot about it, do NOT drink coffee with milk in it that has been sitting out even if you microwave it.

How to best save brewed coffee for later

Now I want to tell you how you can save that delicious coffee for later without harm to yourself or losing too much flavor. Follow these tips for proper coffee preservation!

– Put it somewhere dark

This only works for pure black coffee. You’ll want to store it without anything in it. So, if you already added cream and sugar, you’d better drink it up. You could get away with storing it if you only added sugar though. Sugar won’t spoil.

– Seal it in an airtight container

Remember what I said about oxygen? You want to prevent oxygen from getting to your coffee. So if there’s a chance you can’t drink all the coffee you brewed, take the pot, pour it into an airtight container and seal it up.

– Know what materials are best

Coffee is best kept in porcelain or some type of treated glass. It won’t leave a flavor behind in your coffee and it keeps it insulated. Unless you have a glass with double walls, it’s not the best option. Plastic is a horrible idea as it leaches into your cup of joe and will have that plastic smell along with it.

Stainless steel is great for durability, but it reacts with your coffee. You’ll be able to taste it. Look for a porcelain vessel that can hold your extra coffee!

But how can you tell if your coffee beans are still fresh?

Look into your coffee and you’ll see the future! Ok, maybe not, but if you look and see that thing foamy layer on top, it’s still fresh. This is the naturally-occurring foam that forms without adding any dairy to it. When you look in your cup and it looks black and flat, it’s a stale cup.

Beans can make all the difference too. If you want to be sure your beans are fresh, do the following:

  • Fill a half-cup of coffee beans into a zippered plastic bag.
  • Squeeze out all the air and seal the bag.
  • Let it sit overnight.
  • In the morning, see if the bag is puffed up. If so, the beans are still releasing carbon dioxide.

This will happen for beans that are in their prime, about 7 to 10 days after they’ve been roasted. If your bag is flat, your beans aren’t producing the gas and aren’t fresh.

You can also check the oiliness of the beans, though do keep in mind that light roasts are less oily than darker roasts. You will still see some oil though which will help you know whether they’re still fresh or not.

Good coffee is everything and I firmly believe no one should have to settle for coffee that tastes like a burnt firepit. It should be balanced and rich with a smooth flavor that soothes your soul and brightens your day. Don’t drink old coffee because you’re worried about wasting it. Make a point to buy quality beans and brew only what you need at the time.


Yes, it’s ok to drink coffee you’ve left out all day if it is black. If not, you need to toss it out and cut your losses. Storing your coffee immediately is the best way to cut down on waste. Put it away quickly before it loses its flavors. You can store it safely in the fridge.

Another cool idea is to pour it into ice trays and freeze it but only if you like cold coffee beverages. You can use it to make frozen coffee drinks or even caffeinated milkshakes later on.

Regardless, try not to forget your precious coffee. Make sure you’re buying the best beans at their peak of freshness without going overboard. You’ll wind up with stale coffee when you buy too much at once.

Save the coffee! It’s my new campaign. Seriously though, save it properly for later and you may just have a chance at having a decent cup when you come home.


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