Water keeps everything working at its best. Which includes muscles, bowels, kidneys and of course our brains. Here’s a couple articles from a quick search.
And here’s one study on the brain. https://onlinelibrary.wiley.com/doi/full/10.1002/hbm.20500
There are literally hundreds if not thousands of articles and research on hydration. IMO if one has ruptured, we need to restore the balance as quick as we possibly can, water and protein are the magic pills for this as both aid dramatically in healing. If one has been coiled, keeping hydrated prevents constipation and thus we don’t have to push to extract feces which can have a negative effect on BP, thus the coils. It also helps in short term memory and cognition. My BH was involved in a diet task set at work. A glass of water before coffee helped tremendously with weight loss.