How many ounces of water should I drink everyday?

I read/heard somewhere to drink half your weight in ounces. A 150 lb person would drink 75 oz per day. I don't know how reliable this information is but I've heard it more than once.

I'm not qualified to give medical advice, however for conversation purposes...

I was told the following formula by a nutritionist relative: (weight in pounds)/2 = # ounces of water that should be consumed daily. For example: a 200lb person should drink 100oz of water per day. This water consumption should be spread fairly evenly through the day. I'd invite you and other forum readers to search the web for more information. People with BMI percentages in the upper 30s should consult a doctor about water consumption to avoid potentially unhealthy situations. Don't over do it - too much water can cause very dangerous imbalances in the body.

This site mentions the above formula near the bottom of the page:
http://www.drstandley.com/food_water.shtml

The Mayo Clinic has the following to say, which suggests there really isn't a set formula we all can follow:
http://www.mayoclinic.com/health/water/NU00283

hyponatremia - (over hydration):
http://www.mayoclinic.com/health/hyponatremia/DS00974