Edit: I noticed that since the April 13 update, Sims also seem to be drinking milk and orange juice autonomously even when Hunger is in the green.
Back in December 2014, a rule from the update has been added to prevent Sims from drinking from the fridge autonomously but it appears that this rule is broken notably as of GTW/version 1.5.
It happened in my game where I had two Sims, Rebecca and Ashley. Rebecca made a Sunset Valley and then I put it on the fridge, later I spotted Ashley drinking the Sunset Valley despite the rule stating that Sims will no longer drink from the fridge. Unfortunately, EA partially altered the rule. While it was supposed to prohibit Sims from drinking from the fridge autonomously, it doesn't stop them from attempting to make drinks or drink any drinks and they'll do this regardless of Hunger levels.
To get around this problem, I moved the Bar to the Household Inventory so that the Sims would not make any drinks. I only take it out to do Rebecca's daily task or to make potions. I've made a thread at The Sims forums discussing this issue.
This is one of the bugs that didn't get fixed in the March 26 update. However, Sims drinking from the fridge autonomously might be a bug.
As of the Nov 15, 2016 patch, it's still happening, however not so much out of the fridge anymore, so this might need to go under a different topic.
Whenever anybody comes to my apartment because I've given them an apartment key (City Living), they're constantly going to a sink and drinking glass after glass of water, and not doing much else. I'm constantly cleaning up after my otherwise perfectly lovely friends.
I thought that maybe because it was a tiny starter apartment with not much in it, that's all they could do apart from watch TV, but I had another family in a much bigger apartment and it still seemed to happen, but not as much. I tried curbing the drinking with dancing which worked a bit
I'm not entirely sure whether this has started happening because I've installed City Living, but the problem is definitely more prevalent because of it, now that my friends can come over whenever they want to. I never really asked my friends over before now.
