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.
My sims as well are excessively drinking water. Have nothing to do for 5 minutes? Get a glass of water. Leave it somewhere because you got distracted. Get another glass of water.
No mods, no CC.
