Quite honestly, I wouldn’t worry about it so long as their poops are firm and they’re pooping throughout the day. Plus, only a handful of tablets sold for rabbits actually do anything good for them, and unless my buns just weren’t pooping or their poops seemed too off, I wouldn’t want to waste my money on something that could possibly do nothing or worse, do something negative for them.
As for the water, I don’t have any ideas besides wet veggies and just simply providing the water:s