I think stay in line - at least the way I'm thinking of it, is a lot more negative than just bring an extra bottle. It's a demand for employees to skirt the rules or else they'll be punished and if they're caught skirting the rules they'll also be punished - oh and since you're a contractor you lack any rights normally afforded employees.

Basically, sit down, shut up and take it - we've got the power and if you try and object we'll can you and replace you faster than you can blink. And we might even find a way to make sure you can't qualify for unemployment.