"Hydrate or Die." It's a registered phrase that is used by CamelBak in their marketing campaigns, but it's a healthy truth that has been medically supported for decades. "Water is life," "Without water we die..." Whatever the phraseology, the message is the same. You have to drink. Nalgene has built an empire around the wide-mouth water bottle. Entire expeditions, adventure races, casual backcountry forays all share the same basic human need-the need for hydration.

It could be argued that the first truly effective hydration systems began to evolve when forward-thinking companies explored ways to carry water bottles outside a pack. Water bottle carrying pouches that snapped on or strapped on to compression straps or a pack's waist belt were the initial forays into a design philosophy that concluded a person was more likely to drink if a drink was readily accessible and did not require removing a pack.

Though bladder systems (the first was created by Camelbak) have been around since 1988 they were of primary interest only to the performance community and garnered little notice from backcountry travelers-until 1993- when Ultimate Direction became the first to combine a bladder with a pack. The rest is, as they say, history. Just about every pack manufacturer is offering some form of bladder hydration system now. Why?

It is no secret that many of the problems associated with physical activity are a result of low fluid intake. Having to stop to pull a canteen or water bottle out of a pack or side holster does not encourage frequent and necessary hydration.

Water bottles have a purpose, but they are really limited in their application and once you have emptied it, you have a hard shell full of air taking up space. The value of a bladder system is that it becomes a multifunctional tool. It's a water carrying devise, a pillow, a shower, a body temperature regulator [add hot water to heat, cool water to chill] and more.

Packs that incorporate bladders into their designs make it more comfortable to carry large quantities of water and make it easier for an athlete or backcountry traveler to drink, which in turn helps to minimize the possibilities of suffering from symptoms such as headaches, nausea, heat illness and altitude sickness.

Preventing Freeze-ups Sure, water freezes when it gets cold and a frozen drinking hose will put the kabosh on any attempt to suck and sip, but you can prevent your hydration system bladder and hose from freezing solid during the winter months.

According to the folks at both CamelBak and Ultimate Direction, keeping your bladder (that's the one you're wearing, not the one you're born with) from freezing means wearing a layer of clothing, such as your outer shell, on top of the bladder. The drinking tube should be routed up near your neck, remaining under the outer layer until it is time to drink. By drinking in small but regular intervals, the fluid will not freeze. In bitterly cold temperatures, you can blow air into the tube, forcing water back into the bladder. Ice may then coat the inside of the drinking tube, but it won't freeze shut.