I learned years ago, while on active duty with the Navy, that you should salt your food to taste and drink plenty of water. Watch your urine. If it turns dark you're not drinking enough. Drink before you feel thirsty. If you're in a hot environment, you may need as much as a quart an hour. I was on a Combined Arms Exercise at 29 Palms, Ca. in August, 1980. I was drinking a quart of water an hour and each time I finished my canteen, my skin grew cool for a few minutes. I was just keeping up with my body's requirements.