Originally Posted by Riot Ambassador
Be sure to remember that going AFK in game for a short period of time will also cause your account to be flagged for leaving. Be sure to do everything you can to complete your games fully without leaving, most Summoner Rift games are an average of 30 minutes.
I play on a daily basis, and almost every night I have to go afk for <1-2 minutes twice in one game (both due to my wife's and my nightly ritual for tucking her in, since she goes to bed considerably earlier than I do). I make it a point to try not to be in a game with too many pugs when this happens, and it's never had an adverse effect on my games (I make her wait a few minutes if I'm stuck guarding a tower or pushing, or if I expect to die soon). I've never been warned for being AFK, and have only one or two leaves on my account--due to tornado-related power outages.
To me, that means the system is working as intended. If I ever receive a warning for being afk, I'll ignore it, because I try very hard to be present when the game is running and not leave early unless there's a legitimate emergency. If I ever get suspended for it... well I'll just quit, because to me that means that someone turned a knob too far somewhere, and putting my wife to bed is a lot more important than this game.
That's my experience at least, and I share it to say to the OP--hey man, if you need to go get a drink from the fridge, go get it. They're not clocking your APM to see whether you're there. If you have to drive to the corner and buy one along with a tank of gas, though--yeah, don't do that.