My way around that was that I ordered water and soda for my room the first day of the cruise. I generally drink a large bottle of water every day and sometimes two. Then I just took what I wanted from my supply. I bought in port a few diet Cokes and had those in the fridge. It was not terrible signing for drinks the few times we did.

VOYAGER:
MC to FLL 11/07
MC/Dover 6/06
MARINER:
BCN / Ven 10/11
Alaska 2001|2006
Panama Canal 2003
NAV
Caribbean 11/06
Bermuda|New Eng/Canada 6/04
PG 5/05
OCEANIA
Nautica |Ist/Athens 6/07
Regatta|Baltics 6/08
Riviera 2013 Crossing -Istanbul to Miami