There are some people that will insist you should do the sign "EVERYDAY" as the first sign in this sentence. Honestly, I personally tend to just sign: "HOW-MANY CUP WATER YOU DRINK EVERYDAY YOU?"  When I sign it like that I tend to start the sentence with my eyebrows down (for the "wh" question) but end the sentence with my eyebrows going up as if I were asking the yes/no question "Do you mind telling me?"   But that is a bit complex to defend when my colleagues challenge it. 
For simplicity sake I'm just going to show you this general version:
WATER YOU DRINK EVERYDAY HOW MANY CUPS?  (Scroll down for another version).

In this next version you can see how I'm taking more time to emphasize "CUPS."  This version helps clarify that I want to know specifically the number of cups that are being drank on a daily basis.  Plus I put the "HOW-MANY" and the end which fits in nicely with traditional ASL grammar.  WATER CUPS YOU DRINK EVERYDAY HOW-MANY YOU?