Your points are valid.  Talking with your doctor is certainly the way to go. 

As for me, I am 67 and drinking very much water makes me nauseated.  I drink about 3 glasses a day with my meds and maybe milk or juice occasionally. 

I do drink more when on sinus meds or have a virus or on antibiotics.

I have an overactive bladder so would spend all day AND night in the bathroom if I drank more.

We all agree water is important.

Elaine