There are several different ways a lot of these scenes could be done. Here are at least three that I know of:
Everything is set up and the camera gets a clean picture of everything. Then when the actor goes in with their green screen they can be painted out or rotoscoped out. IE, they layer the live shot over a static shot and cut out the green screen to reveal the layer below.
In a shot where an actor might interact with something, they might have a prop that the actor interacts with, and then in post they create a CGI object and put it in it's place.
Strings/Motors/Other Practical Effects
Another way that certain shots could be completed would be to have it done practically. IE, a string is attached to the faucet and it's pulled and the string is rotoscoped out. Or they could have it attached to a motor that they control off-screen.
The takeaway is that there are probably countless different ways these sorts of scenes could be shot, but I've done my best to highlight what I think are the most likely.