How to Water Fast?

This may be a silly question, but how do you do a water fast? Are you supposed to literally just drink water? Are you drinking any teas?

Please keep in mind when answering that I am interested in doing a Water Fast strictly for weight loss. I would like to know how to best prepare myself when I start my water fast. As of right now, I am still doing a Master Cleanse and plan to eventually ease into a Water Fast and do the Water Fast until I reach my goal weight.