I think that I have found out how much is too much.
Apparently, coffee (well caffeine in general) will actually dehydrate you. If you drink nothing but coffee for....lets say.....3 days, you get a killer headache from dehydration. I thought that I was getting a caffeine headache because it had been a few hours since I had a cup a coffee. Half a pot of coffee later, the headache was worse.
So, being the intelligent soul that I am, I decided to drink a bunch of water to hydrate myself. In hind sight, this was not too smart. When you are dehydrated, your body will quickly store the water that you drink. If you quickly drink a bunch of water, your body very efficiently stores it.
So, I am no longer dehydrated, I no longer have a headache, but I feel like a water balloon. LOL
Morale of the story- you need more in life beside coffee...... but coffee still gets a 5 coffee cup rating, because, well....it's coffee!