I am thinking about doing some 5 gallon kegs but I am concerned about how long the beer will stay fresh. I know that when we a keg for a party a few years back the beer went flat and stale just a few days after our party. But we used a hand pump to pressurize the keg so I figure all the air in the partly drained keg had a lot to do with that. But if the proper CO2 levels are maintained then no air would get in and carbonation should remain as well. So what is the shelf life of properly kegged beer?