The site did email me back, with a link to this site, however, there's no data to back up their assertion!
How much water do I need each day?
Although the question is rather simple, the answer is much more complicated. Unfortunately, there really is no one-size-fits-all approach to the amount of water you should consume on a daily basis
As a general rule of thumb, you should try to drink between half an ounce and an ounce of water for each pound you weigh, every day. For example, if you weigh 200 pounds, it is recommended you drink 100 ounces of water if you are performing non-strenuous activities
If you are going to be working out or hiking, you definitely should add to those 100 ounces. It is recommended that you drink 12 ounces of water a couple hours before your activity and then another 12 ounces about 30 minutes prior to the start. Be sure to also drink throughout the activity
Other factors to keep in mind when thinking about your daily water consumption include the environment and any illnesses or health conditions. Hot or humid air makes you sweat more and will require additional intake of fluid. If you are sick and vomiting or have a fever, you will again be losing fluid more quickly and need to replenish
As you can tell, being properly hydrated is important but not a perfect science. The best approach is to listen to your body and look for the feedback signs