What's your most important piece of golf equipment? Your putter? Driver? Sand wedge? According to Stanford golf coach Wally Goodwin, it's your water bottle. "Dehydration happens before you know it," he says, "All of a sudden you're tired, you lose energy and your common sense, and once you've lost it, it's gone."

Even at rest, your body loses fluids as it cools itself, with respiration, radiation and perspiration. Drinking eight glasses of water per day is recommended on a regular basis, but while playing a round of golf, especially in hot and humid, or dry weather, it is especially important to constantly drink liquids. Dehydration results if you lose more fluid than you take in. Your body's fight to regulate its heat and fluid levels, can lead to dizziness, confusion, low blood pressure, muscle cramping, and increased heart rate--or in advanced stages, heat stroke, heat exhaustion--or even death.

Thirst is the first indicator, but by the time you're thirsty, it's already late to start drinking. "Each time you get into the cart, it's a good idea to take a drink of water," says Dr. Joe Picone, a South Florida chiropractic sports physician, "Your body loses electrolytes, like potassium, sodium and calcium, as well as glucose while you're playing and perspiring, so you need to replace those immediately with sports drinks or juice to keep your muscles and mind in the game."

Contrary to popular belief, salt tablets are not recommended to ease dehydration. Salt does increase thirst and the need to drink, but drinking water in advance is still the best preventative measure. This is especially true for older people, who tend to lose their sense of thirst, diabetics and those with low blood pressure who may take medication that can be dehydrating, and young children who are particularly at risk. Caffeinated drinks like colas, coffee and tea are also dehydrating and should be avoided. So what about that cold beer that looks so inviting as the beverage cart makes its rounds? "Beer is not the fluid you should be consuming," says Dr. Omart Robaina, Professor of Family Medicine at the University of Miami Medical School. Alchohol decreases the capacity to sweat, increases urination, impairs judgement and the perception of being thirsty, and can delay recovery from dehydration. "Save the beer for the clubhouse, after you sit down, cool down and have a drink of water first," he advises.