I leave my serving lines and picnic tap connected to my keg at all times, so there's beer leftover in the lines after the last pour. Does this stay carbed, or should I pitch it whenever it's been sitting there awhile?
I use picnic taps and 10' lines which are always on the kegs in the fridge. When pouring, there is a noticeable transition in carbonation when the beer from the lines switches to new beer pulled from the keg. But even with 10' lines, this is about half a small serving. So I never bother. The new beer which come in still supplies a sufficient head. No ill effects seen on taste and mouthfeel. I doubt the beer in the line is completely flat, but definitely lower than normal. I never pitch it.