Play around with it, see how it works for you. Start your day with two 16 ounce glasses of water, before coffee or breakfast and drink plenty during the day. Drink a glass before lunch, and ditto before dinner. A gallon is certainly not too much, and again, if you live in a hot humid climate, it may not be enough. I have lived in both Texas - hot or hot and humid - and Minnesota - very cold but dry cold - and found that people did not drink enough water.
Players may also burn certain items in Bonfires to achieve effects. Bonfires serve as access points for Item Box drops. Due to the lack of a pause feature in Dark Souls 2, Bonfires are an integral point for players to take a break from play.
To be properly hydrated and get rid of dark circles you must drink your body weight divided by 2 in oz of water. ex. 135 lbs woman should be drinking 68oz of water per day. A 180 lbs. man should be drinking 90 oz of water per day.