if "a pint's a pound the world around" is true (and it think it is) then it's probably not possible to replenish four pounds of water per hour. maybe two.

BTW, according to some, a 10% loss of water weight will result in a near death experience. we are about 60% water (60 pints per 100 pounds of body weight in males). so a 100 lb person that's running a 6 pint water deficit won't be feeling too good. and a 200 pounder could afford to lose 12 pints before feeling the same effects, on average.