As with anything, it is possible to have too much of a good thing, and that includes water. Look at this link to an article on the subject on the National Institute of Health. www.ncbi.nlm.nih.gov/pmc/articles/PMC17700
I try to aim for at LEAST 10 cups. Since I am so heavy, I do need to be especially sure I stay hydrated. I get really bad headaches when I'm dehydrated, to the point my teeth hurt and my lips burn. If that's the case, I guzzle several cups of water to try to keep up. I have my coffee in the morning, and the rest of the day, I drink either cold tap water or room temperature water, though I do still occasionally indulge in ice cold water. I also need a big cup of water by the bed at night, because I wake up to use the bathroom and my tongue is stuck to the roof of my mouth. I'm fairly certain I snore. Sexy, right? hahaha.