Ninety percent of muscle tissue is comprised of water. If you want bigger muscles, you must increase your water intake. Water is also a benefit in the sense that in order for the body to adapt to a new weight, it must get used to being that weight. The body wants to maintain a state of homeostasis. This is the reason why you can gain or lose weight one day, but it will just go back to where it was the next.
Water is a great way to quickly add weight.
That's why it's imperative to remain well hydrated - constantly. It's also important to note that thirst is not a good indicator of fluid requirement. You might also consider supplementing with 5-10 grams of creatine monohydrate daily to increase water volume within the muscles. Take dessicated liver tablets. Liver tablets have fallen out of favor due mostly to promoters of high-tech supplements who want you to believe that their products are superior.