Expert: Ed Westemeier - 7/2/2002

Question
Once a 1/2 barrell keg has been tapped, how long is it good for?

Answer
If you're using the standard tap that usually comes with the keg (the kind where you pump it a little by hand to keep the pressure up), then the beer will stay fresh for up to two days, depending on the temperature. The reason is the air you're pumping in to keep the dispensing pressure up. The oxygen in the air reacts with the beer to cause it to go stale (oxidized).

To keep it fresh longer than that, you need the kind of tap that uses a CO2 tank. Most beer distributors don't stock them, so if you're getting kegs a lot, then you might consider investing in one. Should cost less than $100, but lasts a lifetime (with periodic refills of the CO2 tank).