I agree with Girl_llla. I also know that some people don't get as thirsty as others and the climate we live in plays a huge role among our activity levels and health conditions. My son, my own flesh and blood could go most day on very minimal water. Me and my mother on the other hand, we drink lots of water all day long, always have!
I think it's just like everything else...you have to really listen to your body and know what YOUR body needs. I believe my son is just fine not drinking as much water as me. He's much healthier than I am by all means! (little stinker)
"Nothing taste as good as thin feels"