How much water should i drink while exercising and can too much water cause damage?

8 oz every 15 mins: To max your workout 16-20oz water 1-2 hrs b4 workout & another 8 about 15 minutes or so beforehand. During your workout, 8oz per 15 mins should suffice. If heavy sweating more than 1 hour then replenish electrolytes with 16 oz fitness drink. You can drink too much - very unusual but potentially dangerous condiiton called hyponatremia. Weigh urself before and after w/o & adjust if losing weight.

Hydration: Rehydration rates vary by the perspiration and heat conditions. Rule is to replenish same volume of water lost to perspirstion & heat evaporation plus metabolic respiration of cells. But more importantly replenishing electrolytes. This balance of lost electrolytes in isotonic body fluids such as sweat and urine is key towards maintaining homeostatic metabolism and euvolemia during strenuous act.