Wow, sorry to hear about all this Stacey. I struggle trying to understand the whole refusal to drink water that so many people have because they don't like the taste of it or other reasons. I was a water drinker decades ago and find that it is so beneficial for so many things. Try smoothies and use coconut water. It will help hydrate quicker, he may like all the things you can do in a smoothie like frozen fruit, add some protein powder, greens in powder like Greens and Whey or something. You can get hydration, fruit, fiber, nutrients and more plus make it however he might enjoy.
Ed