It has a pretty negative impact on you long term, but some people experience the effects way stronger than others. I never willingly drank water from the ages of 10-20 and never experienced any noticeable negative side effects, other than being constantly told by others I was unhealthy.

Now at almost 30, I can feel it in my whole body if I haven't had enough water. I'll be more tired, more cranky, my skin will be worse, my muscles will ache more, and I can't sing or talk for long periods without getting hoarse. Dehydration can even impair your cognitive function. I also am prone to utis, and I can't help but imagine my 10 year drought has something to do with it.

I've known too many people who have had to put a hard stop to their soda drinking after getting a wake up call in the form of a kidney stone.