nick2632I've had drinks in there for 6 days without any discernible hit to the flavor. Also, it cleaned out easily with a good rinse with water. I have used it more as a travel flask rather than a long term storage unit, however, so I can't say whether or not keeping drinks in there for longer than 1-2 weeks would be viable.
nick2632As an experiment, I have sampled vodka after 12 months of storage in this flask with no noticeable degradation in taste. Expiration should not be a practical concern.