Yes, cold brew goes bad after about two weeks refrigerated, or faster if diluted.
Signs of spoilage include sour smell, mold, or off-taste. Concentrate lasts longer than ready-to-drink versions.
Does Cold Brew Go Bad?
Because cold brew is, after all, a food item, it can go bad. The good news is that the shelf life of cold brew is significantly longer than that of hot-brewed coffee: for concentrate, kept in the fridge, you can expect up to two weeks of freshness before you should throw it away. However, it works slightly differently for diluted, ready-to-drink cold brew, which you should dispose of within about a week.
However, it’s worth noting that while it’s still technically drinkable at two weeks, it only takes about a week for cold brew coffee concentrate to start to taste stale. If you pre-dilute your cold brew, that time is cut in half: diluted concentrate loses much of its character within three days.
Delving Deeper Into Cold Brew Freshness
If you want to give your cold brew the longest possible shelf-life without losing its flavor and smoothness, there are a few steps that you can take. While you can certainly store your cold brew concentrate in a plastic container, the porous nature of plastic means that it takes on flavors very quickly. Plastic also takes on oily residue, which can go rancid over time, making your cold brew taste bad.
The best storage option for cold brew coffee is a glass vessel. Glass is non-porous and stands up to more vigorous cleaning better than plastic does. Metal is another option, but it can also take on off-flavors and collect residue from the oils of the coffee.
Another known method to extend the shelf life of your cold brew is to keep it in its most concentrated form for as long as possible. Cold brew concentrate holds up for twice as long as the diluted, ready-to-drink version; it has more compounds that help protect against staleness, so it breaks down more slowly. It’s not difficult to dilute your concentrate to your preferred strength just before drinking, so there’s a strong incentive to keep your cold brew in its most intense state for as long as possible.
Finally, you can ensure a long life for your cold brew by keeping it cold. While it’s not necessary to actually brew your cold brew in the fridge, it can provide a benefit: by staying cold the entire time, the cold brew has less exposure to one of the key factors that cause coffee to go stale.
It takes longer to extract the full flavor from your coffee grounds by brewing in the fridge, so take that into account. Even if you don’t brew in the fridge, you can get the most out of your cold brew by keeping it in the fridge as much as possible.
What To Do With Spoiled Cold Brew
If the two weeks are up and you still have some brew left, you have to throw out some of your cold brew; it doesn’t need to go to waste. You can use your stale cold brew to water plants or as a stain for wood or paper.
Many also swear by stale coffee as an ingredient in hair masks and rinses! Just look for signs of mold or mildew–but generally, it takes about a month for those to start.
Our Testing Notes
We’ve tested this brewing method extensively in our coffee lab, and here’s what the data doesn’t always tell you:
Water temperature matters more than most guides suggest. We found that 200-205°F consistently produced better extraction than the often-recommended 195°F. The difference was especially noticeable with lighter roasts—underheat them and you get sour, underwhelming coffee that wastes good beans.
The grind size recommendations online are a starting point, not gospel. Your specific grinder, beans, and even altitude affect optimal grind. We keep a brewing journal and adjust by one click finer or coarser until dialing in a new bag. Takes about 3 brews to nail it.