I've had a few doctors tell me to drink more water. But I don't remember if they told me how much to drink.
I usually don't drink more than 20 oz of water a day.
How many ounces of water do the folks here average per day? I saw online that men should drink 125 ounces and women should drink 91.
This is not really accurate - lots of "estimates" are based on little or no science. Remember that you get liquids in the food you eat and other beverages count and those count as part of your total.
Did the doctor cite lab tests on creatine or BUN? Or just a generic "you need to drink more"? Get some specifics from HIM.
You likely COULD stand to drink more but it can be tea, coffee, flavored water, etc. as long as it doesn't give you a lot of calories from sugar/carbs. Just try drinking a couple "extra" 12 oz. glasses a day - say an extra glass in the morning and the afternoon in addition to your meals and other stuff. Don't go crazy and think you need to drink an extra gallon and just give up (that's a crazy amount and may damage your kidneys and mess with your electrolytes - more is not always better!).