I could be way off base, but I know I have been borderline diabetic in the past, and extreme thirst is a symptom of that. It could just be a temporary thing due to the fact that your body is learning how to adjust to your new way of eating. If you did consume a lot of sugar previously, and suddenly stopped, I would think this could be a strong possibility. The good news is that paleo is a perfect way to "treat" diabetes! I used to drink a gallon a day, but it mostly due to boredom... my job was.. lacking. :) Dependent on how much you weigh, this can be an acceptable amount, I just hope you are able to stay close to the bathroom!

I would not drink that much water, water can also be toxic and even kill if drank in huge quantities. The 'feeling thirsty' symptom is just that: a symptom of something else (diabetes?). Please go to your doctor as fast you can, today.

Interesting. This isn't an issue I had when making the switch. Could it be that you are increasing your water intake in order to take your mind off of food or feeling hungry? For me, when transitioning to Paleo I found myself using coffee as a crutch to suppress my appetite throughout the day. I no longer need the coffee, although I still enjoy it whenever I feel like it. Is it possible that your switch to Paleo coincided with increase in physical activity resulting in dehydration?