Full Lecture Transcript (Cleaned)
The Ruling — 23:02
No doubt it is better, when you're able to, to sit down when drinking. However, there are a number of traditions showing permissibility of standing.
For example, Ibn Abbas drank water while standing, and then he looked at somebody staring at him and said: "I saw the Prophet (peace be upon him) drink water while standing" -- as if to say, "Don't look at me like that, I saw the Prophet do it."
The Scholarly Position — 23:35
What the scholars say is that when the circumstances warrant it -- like at a drinking fountain (what are you going to do?), or at your office water cooler where everybody is standing -- no problem.
But if you are at home and you have the luxury, then it is better out of adab to sit. However, it is not something that is mandated.