I am a very strong believer of this, and have been for many years.
The body is already ~75% water, so keeping it refreshed with good clean water is essential.
If you want to really look into it, look into “intra-cellular hydration” which os one of the greatest secrets of maintaining good full body health.
Have had two elderly relatives who started showing signs of confusion. One, a doctor thought it was the start of dementia but it turned out with both of them that their confusion was caused by urinary tract infection due to not staying hydrated. Once the UTIs were addressed, they both started acting normal. I share this in case you have elderly relatives.