http://us.battle.net/wow/en/forum/topic/1827307392
Chug-A-Lug - Rank 1
The duration of buffs from all guild cauldrons is increased by 50%.
Alchemists normally get two hour flasks, whether it be their own flask or a flask from a cauldron. Once a guild reaches level 10, they unlock the Chug-A-Lug guild perk which increases the duration of all guild cauldrons by 50%. This should bring an alchemists flask up to 3 hours, but it's doing the opposite and decreasing it by 30 minutes, down to 1.5 hours.
I'm assuming this isn't intended.