I know that you're supposed to drink 8 glasses of water per day. Is that the standard for everyone?

Yes. This is the standard recommendation for healthy individuals. If someone has severe underlying medical conditions such as kidney disease or congestive heart failure, then less volume may be recommended.
Myth. An average adult might benefit from the equivalent, but should never use this as a guide for actual consumption.Many of the foods we consume have water content.Apple sauce is 95% water, most fruits/vegies 60% and their input counts.Normal people just need to drink enough to pee every 8 hours or so.
No. The eight glasses of water is overkill for many people. Drink when you are thirsty. Increase your intake when it is hot or you are exercising. People with congestive heart failure need to limit their intake of water.