slaves usually just get fed stale tapwater and gruel, often out of the same feeding bowl. I make sure to handfeed mine scraps of the cooking they do for me occasionally, both for fun but also to help improve food service, a slave needs to know how the human food she makes tastes even if its not for her.

I am somewhat soft towards these things, so the rare human meal as a great reward has also happened a few times, alongside a slave deep in misery and suffering being taught to understand Master's rule over her life is benevolent with something like picrel, drinking a human drink straight from her Master's hand, but there's still other ways you can have fun with this reality of her life day to day.

Best to use just the Ice Water she makes you. Not the coffee or any of the fancier stuff depending on what you're into, but during some lazier days where she just has to serve you around the house and doesn't have that much chores to do, can have some fun rewarding her for keeping your floors absolutely spotless.

Just drip some of your drink on the floor. Not too much, not right to spoil such a creature. Make sure she understands she is supposed to immediately drop to the floor and lick it up, thanking you profusely for every drop. slaves are ultimately but dirt who must redeem themselves with exemplary service every day in order to receive the bare minimum, any lack of respect for treating her as anything more should be dealt with immediately.