Can You Reuse Coffee Grounds for a Cold Brew?

Picture of coffee grounds submerged in cold water

Every day, coffee lovers across the globe are finding new ways to get that caffeine buzz without wreaking havoc on the environment. One way of practicing sustainable consumption is to reuse things around the kitchen – but what about your old coffee grounds?

What’s the Difference?

Chances are, you’re reading this because you’re curious about how reusing coffee grounds will impact the quality of your coffee. The truth is, many unique factors fall into play when it comes to brewing that perfect cup. Some of these things include the brewing temperature, your coffee machine, and the initial quality of your coffee grounds.

Although it’s possible to reuse coffee grounds, it does change the makeup of your coffee to its core. Some people enjoy a reused-grounds cup of coffee as a lighter follow up to their initial cup, while others believe reusing grounds to be a cardinal sin of the coffee world. It’s important to be prepared for anything, just in case the new flavor isn’t for you.

Saving Coffee Grounds

When looking to reuse your coffee grounds, plan ahead. Immediately after brewing your first, fresh cup, you should remove the grounds from your coffee machine. The first thing you need to do is gently-pat dry the used, wet grounds until all the excess moisture has been removed. This is critical because that moisture, if left unattended, will invite unwanted bacterial growth.

Why it Works for a Cold Brew

It’s better to reuse coffee grounds for a cold brew, instead of a second hot cup. This is because the cold brew process involves soaking the beans for a longer period of time, thus extracting even more flavor. 

Cold brew coffee is also usually made with dark, strong coffee beans, so the bitterness you’ll experience with reused grounds isn’t off-putting. Most people load up cold brew coffee with cream and sugar anyway, so the strength of the grounds is less important.

When you brew a hot cup of coffee, the brewing temperature is very high, which can ruin the tannins in your coffee. This creates a bitter taste and flat, stale flavor – which is definitely not what you want. However, you can create a cold brew using nothing but the grounds, water, and a container. Since no heat is applied during the process, the grounds will retain more flavor.

What Does it Change?

The Color

Reusing coffee grounds can affect the color of your coffee. Usually, the second brew will have a diluted appearance and a duller color. It can sometimes look like an iced coffee that was left out for too long and became watered down. This may look visually unappealing, but it’s preventable.

Try using dark roast beans, which retain their strength and flavor a little longer than a light roast. When making the cold brew, using less water to soak the grounds can give it a darker color. Adding cream and sugar or other fixings can also improve the coffee’s appearance.

The Taste

Reused coffee grounds create a flatter tasting coffee, and that’s indisputable fact. However, you can somewhat dodge the flavor change by purchasing higher quality coffee beans. Better beans will retain most of their flavor seven after the second brew. Again, adding cream and sugar can also help improve the taste.

The Caffeine

The big question is, how much caffeine will a reused brew give you? Unfortunately, most of the caffeine in coffee is extracted during its first brew. An average fresh cup of coffee contains about 12 mg of caffeine per gram. You’ll only receive about 3.6 – 8 mg of caffeine when drinking the reused cup.

This doesn’t have to be bad news, though. Many people enjoy cold brews with reused grounds at home because the second cup isn’t as intense as the first. The lack of extra caffeine can be a great pick-me-up during a sluggish afternoon without giving you the jitters.

Is it Safe?

As long as your coffee machine is well-maintained, free of residue or debris, and the grounds are fully dried, yes, it is generally safe to reuse coffee grounds. Ideally, you should make sure to reuse the coffee grounds within the same day of their original brew to prevent bacterial growth or staleness.

Making a Reused Cold Brew at Home

Fortunately, making a reused cold brew from the comfort of your kitchen at home is a relatively simple process. Here’s how to do it:

  1. Collect and fully dry the used coffee grounds.
  2. Soak the grounds in a mixture made from a 1:4 ratio – for every 1 cup of grounds, use 4 cups of water. If you want an even stronger cup, you can adjust this ratio to a 1:1 or a 1:2.
  3. Cover the mixture and refrigerate it for 12-24 hours. The longer it stays in the fridge, the stronger its flavor will become.
  4. Strain the coffee out using a strainer or cheesecloth.
  5. Finally, enjoy your environmentally friendly cup of Joe!

Other Ways to Reuse Coffee Grounds

If you want to reuse your old coffee grounds without having to drink them, there are many ways you can recycle them in other areas of your life. You’d be surprised at all the uses there are for old grounds, from your bathroom to your garden and everywhere in between. Here are some great alternative uses for those old grounds:

  • Garden fertilizer
  • Skincare scrubs & exfoliation
  • Compost
  • All-natural pesticide
  • Air freshener/Odor removal
  • Natural dye
  • Certain baking recipes
  • Household cleaning

Coffee contains many unique properties which promote healthy growth, and it can do wonders for your skin and hair. It can also help reduce inflammation and puffiness, especially around your eyes, if applied to your skin. No matter where those grounds end up, they’re bound to be useful!

Fresh is Best

Although brewing reused grounds means sacrificing some of the caffeine and flavor, it can be a great way to practice environmentally conscious living. Even if a reused cold brew isn’t your style, those old grounds can come in handy in other ways. We all know that first, fresh cup in the morning will always hold a special place in our hearts, but reusing your next batch of grounds might be worth a try!