Coffee

No instructions??

Assuming you're brewing 1:5 grounds-to-water and 12-24hr brew time, immersion cold brew brews a concentrate. To serve, you're supposed to dilute 2-to-4 parts water to one part brew. For example, my brewer holds 10oz coarse-ground coffee and 50oz cold water. Let it sit overnight and then filter out the grounds. To serve, pour 1/4 - 1/3 cup concentrate into a mug, and then fill the rest with boiled water from a kettle (for hot coffee), or just cold milk or water & ice for an iced coffee.

Cold brew keeps in the fridge for at least a week. I had one batch of decaf that was in there for nearly a month, but I was starting to be concerned near the end. One week, easily, though. That's my usual MO. I brew something like 50 oz at a time and it sits in the fridge for - well, let's say 5 or maybe 6 days. But I used to brew larger batches and I'd regularly go 10 days with the brew in the fridge, no concern.

Once brewed, in a sealed container it (mostly) stops oxidizing and the flavor doesn't change. And pure brewed coffee doesn't have many sugars to feed mould.

TL;DR: in a sealed container in the fridge, at least a week is fine.