There was a South Beach Daily dish from April 28th called the Word on Water. I'm pretty sure it is posted somewhere here. It said in part:
Even better news: Other beverages — including caffeinated ones, like coffee and diet soda — can help you meet your fluid needs, according to the IOM. Low-fat and fat-free milk are other South Beach Diet®-friendly beverages that can help you meet your fluid requirements. Foods that contain a lot of water, such as vegetables and fruits (Phase 2), also count.
It also says that you don't need to count the amount you consume but should use thirst to guide you.
I still try to make sure I drink water some but I have to admit there are days when I drink more Crystal Light.
Barbara - Started South Beach 5/22/4 Restarting 8/15/16
HW/SW/CW/GW - Aug start 213 goal of 2