Do you have to drink a lot of water for intermittenfasting to work?
Also, do you have to quit sodas completely?
Personally I don’t think anything that makes you give up something completely that you enjoy will work. Make it work for you. Limit your intake of sodas and only have them during your eating window. Drink water during your fasts. Track it all and see how it goes for you. If giving up soda completely is going to make you miserable then I wouldn’t recommend it.
I’d avoid them as much as possible for 6 days per week then have a diet soda as a reward for a job well done. That said, if you have them during the week, drink sodas only during your eating window or else they will instantly stop the ketosis that you started with IF.