Cold brew concentrate lasts 1-2 weeks in the fridge. Diluted cold brew is best within 2-3 days.
The concentrate stays fresh longer because the higher coffee concentration inhibits bacterial growth. Once diluted, drink it within a few days for best flavor.
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.