Ugh. One doc says 2 lit. another says 3. The phlebotomist said 3 and the water jug said eight SIX ounce glasses. Say what? Then the friend said it depends on activity and weather... and now I'm confused.
I would definitely listen to a doctor before I would listen to a jug label If your phlebotomist is recommending 3 liters a day, there may be a reason, so I would trust his judgement. It certainly won't hurt you at all to be drinking that amount. There isn't really a "right" amount of water--it's whatever works best for you (or whatever your doctor tells you to do ).
I would listen to your dr, but the amount of liquid you take in during a day in your food. There are foods that naturally have more liquid (fruits and vegetables) and ones that have less (baked goods, etc.).
I am a nursing student and we have been told to recommend 2,500-3,000 cc's a day orally. So yes, 3 Liters sounds right... But some of that can come from your food intake as well.. so if you are eating water-rich foods like watermelon or apples, then you can consider that as a portion of your oral intake.. so maybe aim for 2,500 cc's; however, if you are not consuming water rich foods then its best to aim for 3,000 cc's or 3Liters of water a day.
The "right amount" of h20
If your phlebotomist is recommending 3 liters a day, there may be a reason, so I would trust his judgement. It certainly won't hurt you at all to be drinking that amount. There isn't really a "right" amount of water--it's whatever works best for you (or whatever your doctor tells you to do 
