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First off, you shouldn’t be working out 6 days a week unless your leaving at least a full days rest between working the same muscle group again. Working out 6 out of 7 days a week on the same muscle groups will do nothing but hamper your muscle growth, and leads to over exertion over the long run.

You should be having enough water everyday where your never really thirsty at all. Just keep a bottle with you, take a sip every now and then, if you find yourself having a mouthful then you need to hydrate some more. There hasn’t really been any convincing evidence on the whole ‘have 8 cups of water a day’ theory, so it all depends on your body really. But you should hydrate heavily 2-1/2 hour before your workout.
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Fighting sports trainer

you should drink only when you are thirsty.
Popular culture is loaded with myths and half-truths. Most are
harmless. But when doctors start believing medical myths, perhaps it’s
time to worry. In the British Medical Journal this week, researchers
looked into several common misconceptions, one of them being the
belief that a person should drink eight glasses of water per day. "We
got fired up about this because we knew that physicians accepted these
beliefs and were passing this information along to their patients,"
said Dr. Aaron Carroll, assistant professor of pediatrics at the
Indiana University School of Medicine. "And these beliefs are
frequently cited in the popular media." Myth: You should drink at
least eight glasses of water a day. Fact: "There is no medical
evidence to suggest that you need that much water," said Dr. Rachel
Vreeman, a pediatrics research fellow at the university and co-author
of the journal article. Vreeman thinks this myth can be traced back to
a 1945 recommendation from the Nutrition Council that a person consume
the equivalent of 8 glasses (64 ounces) of fluid a day. Over the
years, "fluid" turned to water. But fruits and vegetables, plus coffee
and other liquids, count.
http://www.livescience.com/health/071220-medical-myths.html
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Its very very very important that you don’t work the same muscle groups on consecutive days, remember your muscle builds while your resting not while your working out- if your able to do it 6 days a week without feeling tired then your body isn’t being challenged enough.

Just drink enough water so that your not thirsty.
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6 days per week is a lot.unless you train each muscle everyday.like rpofessional bodybuilders do.
if you are taking creatine supplements then you mst drink about 3 litres per day.for efficient mass building you muscles need water.of course you will excrete the excess of it.

just make sure you have the necessary mineral ions in your diet.because you might lose some while excreting the excess the water.
you body wont get intoxicated with water dont worry!!!

you need a pause of at least two days after training a muscle group because then you will develop endurance not exclusively mucle mass.
you should have some dextrose before traning ..because it brngs the creatine to your muscle.

i hope i helped you…drink as much water as you want
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i am a medical student.former kickboxing champion, gym training addict