How to quarantine new orchids in a small space

[astrid]

Hey everyone!

I am picking up orchids left and right, and my main collection is pest and disease free. I only have a limited number of shelves in my tiny college dorm, and I am wondering how to go about quarantining my new plants.

I have four new plants from three sources. I don't want to quarantine them all together because a pest from one could spread to the other three.

How far apart do plants have to be to be considered "quarantined"?

Simply not touching leaves and not sharing water?
A foot?
On opposite ends of the shelf?
On completely different shelves?

How long should I keep the plants quarantined? Should I just keep an eye and put all my plants together after repotting or what?

Thanks, everyone!