Can You Reuse Coffee Grounds Twice?

About 44% of Americans drink 2 to 3 cups of coffee, while 16% drink 4 to 5 cups of coffee every day. If you are a coffee aficionado, you know how much coffee can cost. So it stands to reason that some of you may try to save money by using your coffee grounds twice. Can you reuse coffee grounds or is it a bad idea? In short, you shouldn’t take used coffee grounds to brew another cup of coffee but there are many useful ways to use brewed grounds!

Can You Reuse Coffee Grounds More than once? Are reused coffee grounds safe or are they a breeding ground for bacteria?

Can it be done, though?

Yes, you can use coffee grounds twice if you need to. However, coffee connoisseurs say this is not at all ideal.

The answer to why you shouldn’t reuse coffee grounds can be understood if you understand the coffee brewing process.

What Happens to Grounds When you Brew a Cup of Coffee?

When hot water comes in contact with your coffee, it can result in several chemical reactions. Number one, the coffee grounds “bloom,” which is what you call when the grounds blow up to twice their size when you’re brewing your cup of Joe. Secondly, the coffee also releases carbon dioxide which can be seen in the form of bubbles, particularly if you are using a coffee filter.

If you are using a paper filter to extract your coffee, only the soluble solids in the coffee grounds will pass through the barrier into your cup. However, if you are using other methods like a French press, Turkish ibric, or making an espresso, the insoluble coffee components will find their way into the cup. If your coffee cup remains undisturbed for some time, these insoluble solids will sink to the bottom of the cup. As a result, you may taste a gritty, bitter flavor near the end of your coffee.

Does it Matter How You Brew Your Coffee?

There are several factors that affect the brew of your coffee.

Extraction rate

Most people think that when 20% of soluble solids are extracted from the coffee, it then has the best flavor. Coffee compounds are not extracted at the same rate. Acidic and fruity notes are the first to be extracted, followed by balanced sweetness, and then bitterness – How to Brew Less Acidic Coffee.

Therefore, too much extraction can make your cup bitter, while under-extraction results in a weak, sour and pale coffee.

Coffee Grind

If your coffee grind is fine, it means there is more surface area that is exposed to the water. As a result, the extraction process is better. For brewing methods that take longer, like drip filters, it is a good idea to use coarser grinds so as not to over-extract your coffee and make it bitter.

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Water Temperature

The ideal water temperature is usually found between 195 to 205 degrees Fahrenheit. This is near to the boiling point, and at this range, coffee compounds dissolve more quickly in water and extraction will happen quicker. This is why cold brews take longer to make and have a weaker flavor and less caffeine content than hot brews.

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Water Temperature to brew coffee

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Contact Time

The longer the coffee and water and in contact with each other, the more flavor and aroma is extracted from them. Hence, generally, short brews have acidic undertones while longer brews are bitter and hence contain more caffeine.


Stirring the coffee while it is brewing also increases the extraction rate. The movement when water pours over the coffee grounds in a filter is also agitation. If you are immersing or boiling coffee, it is good to stir it from time to time to increase extraction.

Additionally, the ways you brew your coffee also dictate how much caffeine you extract in one go. Some brewing methods extract coffee much better than others.

French Press

If you use a French Press, you know the water remains in contact with the coffee grounds for about 4 minutes. The extracted coffee contains about 107.5 mg of caffeine per ounce.

Drip Filter

A drip filter also allows about 5 minutes of contact between coffee and water (percolator vs coffee maker). The resultant drip coffee will have an average of 145mg of caffeine per 8 ounces.


Espresso takes a shorter amount of time to brew, often under one minute. The serving is smaller though and a single shot of espresso can contain about 40 mg of caffeine.

Turkish Coffee

With Turkish Coffee, the concoction is boiled to produce a rich, thick crema that is poured into a cup for serving. Turkish brew usually has an average of 200 mg of caffeine per 8 ounces. That’s a pretty strong drink!

As you can see, the French press produces coffee with the lowest caffeine content by volume. However, even at this amount, using your coffee ground is a moot point since the caffeine and flavors have already been extracted too much for a second serving.

Used Coffee Grinds

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Does Brewing Twice Reduce Caffeine?

As you can tell, the answer to this depends on the coffee brewing method and the science behind it.

When you place coffee grounds in water, it releases a lot of chemicals including caffeine, flavonoids, antioxidants, proteins, and vitamins. When they are properly extracted, they impart the delicious flavor and aroma you associate with a perfectly brewed cup of coffee.

A number of elements go into the first cup of brewed coffee. For one, most of the caffeine that you need for a wakeup call has already made its way to the first cup. Secondly, the aroma, flavor, and coffee oils have already passed out, and reusing your coffee grounds will result in a zero-fragrance and terribly weak coffee. Lastly, all the antioxidants that are associated with the various health benefits of coffee have been squeezed out during the first extraction process.

So if you do decide to make another pot of coffee by reusing grounds, you may end up with an almost decaffeinated coffee. So if you rely on your morning coffee to give you that much-needed kick, brewing your coffee grounds a second time is not a great idea.

Is it Better to Brew a Fresh Cup?

The answer to “how many times you can use the same coffee grounds” can best be answered by the National Coffee Association that says never to reuse coffee grounds. According to the organization, all the desirable coffee flavors are already extracted during the first batch and only the “bitter undesirable ones” are left when you use coffee grounds twice.

Even if you do believe that some flavor and aroma are left in your coffee, there is a large danger of contamination if you reuse your coffee grounds. Even if you reuse the coffee grounds less than an hour after the first, your grounds will have acquired a huge amount of bacteria and fungi. This makes sense since coffee grounds are moist and warm and make an ideal breeding ground for pathogens.

If you think your coffee maker malfunctioned and did not wet your coffee grounds properly, you can immediately run more water over the coffee. This will allow your coffee to stay in contact for a longer amount of time and extract more caffeine from it. This is the only scenario that makes sense for “reusing” coffee grounds.

How Else Can You Use Coffee Grounds?

 If you are saddened by the amount of coffee that shouldn’t be reused and will go to waste, worry not. There are plenty of other ways you can use used coffee grounds that can benefit you at home.

Garden Fertilizer

Coffee grounds contain several key nutrients that are responsible for the good health of your plant, including calcium, nitrogen, iron, potassium, magnesium, phosphorus, and chromium. It can also absorb some heavy elements that can contaminate the soil. Moreover, old coffee grounds can also attract symbiotic worms that are good for your garden.

Insect Repellant

Not only can you use coffee grounds to attract good worms, but some compounds in it are highly toxic to harmful insects as well. You can distribute old coffee grounds to keep mosquitoes, beetles, snails, and fruit flies at bay. You can keep your garden insect-free by sprinkling some old coffee grounds on your lawn and around your plants.


You can use coffee grounds to make a deodorizer as the old coffee grounds contain nitrogen which is a powerful deodorizer against the pungent-smelling sulfur gas that is formed when air is combined with carbon. You can also place used coffee grounds in places like gym lockers, bedroom closets, beneath the car seats, and other places that can grow damp and warm in certain conditions.

Flea Repellant

Commercial flea-removal products often contain harsh chemicals that can be hazardous to your pet’s health. To keep fleas at bay, simply rub some coffee grounds through your pet’s fur after shampooing. Rinse it off and dry your pet. Not only will the coffee ground give a burnished shine to your pet’s coat and it will also keep away fleas. Remember though that coffee grounds are toxic to dogs if consumed.

Using Coffee Grinds for plants

Cleaning Scrub

The rough and gritty texture of coffee grounds makes them a natural scrub and they can be used to clean up hard-to-scrub surfaces, like cookware, oven grill, or sink. Additionally, coffee has antiviral, antibacterial, and antipathogenic properties.

Skin Exfoliant

The coarse coffee particles can be used as a natural exfoliant and can help remove dead skin cells and embedded dirt from your skin. You can mix coffee with some coconut oil to make a bath scrub or mix them with honey to make a lip scrub. The antioxidant properties of coffee can also help protect the skin from UV damage.

Meat Tenderizer

The natural acids and enzymes in coffee can break the proteins in the meat, effectively making your meat tender. The acids in coffee can also enhance the flavor of the meat. Simply add coffee grounds to your favorite meat marinade and rub them over the meat a few hours before cooking. The coffee will form a crispy dark crust on top of the meat.

Natural Dye

For redheads and brunettes, using coffee as a hair dye can give it a shiny, dark, and burnished look. Blondes can also put coffee in their hair to darken the color.

Hair Growth Stimulant

Exfoliating your scalp with the coffee ground can help get rid of shampoo and styling product buildup and dead cells. Research has also found that applying caffeine to the skin can result in increased blood flow as well as result in human hair growth.

Hides Scratches on Furniture

If you have dark wooden furniture, making a paste of coffee and applying it to the scratch can help conceal the damage. You can continue to dab coffee onto the wood until the desired color of the furniture is achieved.

Under-Eye Circle Treatment

Coffee contains antioxidants and caffeine which can help prevent symptoms of aging and reduce under-eye circles. It also stimulates blood flow which can reduce swelling under the eyes.

Final Thoughts on Reusing Coffee Grounds

For a true coffee lover, reusing coffee grounds to make yourself another cup is not an option. A lot of people are forced to throw away their coffee grounds after a single-use.

However, as you can see, there are many great ways to reuse your coffee. So next time you make a cup of coffee for yourself, consider keeping the used coffee grounds and repurposing them.

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Can You Reuse Coffee Grounds to rebrew a cup of coffee? What else can you use used coffee grounds for?
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