Buy three 32-oz water bottles (i.e. Nalgenes).
Each night, fill all three with water, and stick them in the fridge.
The next day, take out one water bottle and keep it with you. Drink it. Repeat until all the water is gone.
Repeat each night.
Note: If you’re not used to drinking lots of water, you will feel sluggish for the first few days of being this hydrated. You will also use the restroom a lot. Stick with it. Your body will quickly adjust and you’ll feel more energized and refreshed than ever before (and your bathroom breaks will decrease — really!).
(This has worked flawlessly for me for going on four years now!)