This may seem like a silly question, but here are a few pointers about the use of water.
It is best not to drink large amounts of water during a meal. This can interfere with your ability to digest food efficiently.
In the summer, when the weather is very hot, it is best to drink water on a scheduled rather than relying on thirst - especially in older people.
A gallon of water weighs about 8 pounds. If you have large, sudden weight losses, this is usually due to water changes in the body. Replacing those losses is very important. Two cups of water will replace about one pound of water weight loss.
If you have health problems such as congestive heart failure or kidney failure, your body can hold on to excessive amounts of water. Swollen ankles or trouble breathing could be evidence of this. Depending on the seriousness of your condition, you may not be able to tolerate 8 or more cups of water. Check with your doctor before making any significant changes in the amount of water you drink if you have any of these conditions.
Drinking unreasonable amounts of water has been know to lead to water intoxication and can be very dangerous.