I started with "Michael is drinking water", which I could convert to "Water is being drunk by Michael", which I could change to the past tense as "Water was being drunk by Michael".
That leads me to believe that I could change "Water is being drunk by Michael" to the future tense as: "Water will be being drunk by Michael". Am I right?
(In case somebody suggests "Water will be drunk by Michael", I believe that has a different connotation because I would derive it from "Michael drinks water" to "Water is drunk by Michael" and then change the tense to future to get "Water will be drunk by Michael".)