As I keg only I usually ferment 21 ltr brews,after hyd samples & kegging I am left with bout 1ltr which I used to toss out[a waste]so I started putting the leftovers into a couple of 15ltr cubes that I kept in the freezer,so after bout 40 brews I ended up with 20 odd litres of frozen allsorts of beer from wheats to stouts so thawed them out- kegged and taadaa a very drinkable never to be repeated beer with unknown alc% but it'll get ya pretty pizzed & an extra kegfull that woulda been dumped-win/win,now I just keep adding to the cubes increasing the mix