How To Choose A Hydration Pack

• Choose by Activity
• Select a Reservoir Volume
• Consider Cargo Capacity
• Get a Good Fit
• Sip Tubes and Bite Valves
• Cleaning and Storage
• Tech Talk: Reservoir Materials (All hydration pack reservoirs are BPA-free)

Once you've used a hydration pack, its benefits become self-evident:

• Convenience: No slowing down or stopping to reach for a bottle. If you can get the sip tube to stay in place (admittedly, not always an easy task), hydration is a speedy, almost effortless task—just grab, gulp and go.
• Efficiency and performance: Since water intake is simpler with a hydration pack, you tend to drink more often, and a well-hydrated athlete is a better performing athlete.
• Cool factor: You can mock your bottle-slurping companions for being the antiquated, time-squandering knuckle-draggers that they are. (Just be prepared for some squirtage when you do.)

Deciding which hydration pack is best for you is a pretty straightforward process.

Choose by Activity

Who ordinarily selects a complete pack already equipped with a reservoir? Who might need only a reservoir? What reservoir size and pack size are best? Here are some general preference patterns we've noted at REI.

As the name suggests, hydration packs are designed principally to transport water, plus a few small extras—in most cases, that is.

Some thoughts on user groups:

Day hikers/backpackers/climbers: Decide between 2 options:

• Choose a pack engineered around a preinstalled reservoir.
  • Advantage: The reservoir should be custom-fitted for the pack, making it easier to access, fill and clean.
• Add a reservoir to hydration-compatible pack.
  • Advantage: Nearly all newer daypacks and backpacks are designed with an interior sleeve or compartment that can hold a reservoir (and offers a portal for the sip tube). If that describes an existing pack you own, you can simply add a reservoir to it. Just make sure the reservoir can correctly fit in the sleeve inside your pack.

Trail-runners/racers/fitness walkers: Specialized "multisport" packs usually emphasize the low weight, small dimensions and stability important to these users. Cargo capacity, however, is small—just enough for keys, gel packs and maybe a minimalist windbreaker.

Cyclists: If you're riding sprints, you may choose to skip hydration packs altogether, shunning even a tiny bulb of potential wind resistance on your back. Yet on longer rides, the convenience of hands-free hydration wins over most cyclists. A key issue: Fit vs. size. Speedsters want a bare-essentials pack that feels light and stable. Long-distance grinders may be more willing to accept a larger load.

Mountain bikers: All of cycling's elements—the frames, the tires, the hills, the risks, the thrills—are bigger here, so in general the packs are as well. The extra cargo space often comes in handy.

Snowboarders and skiers: As with backpackers and hikers, you can either choose a sport-specific hydration pack with insulated components, add an insulated reservoir (look at the CamelBak StoAway) to an existing pack or "winterize" an existing reservoir by adding, say, a bite valve cover (the CamelBak Thermal Control kit) or a reservoir, tube and bite valve cover (found in the Platypus Insulator line). Some snowsport-specific packs include lash points or carry straps to allow hands-free transport of a board or skis, which is a nice feature. Many snowsport packs include insulated reservoirs; some do not.

Select a Reservoir Volume

1L or 1.5L (34 or 50 fluid ounces): A good choice for minimalists, kids, short-distance bike commuters, weight-conscious recreational riders.

2L (68 fl. oz.): The most popular reservoir size offered at REI. It offers a nice balance of reasonable weight and bulk while providing a sufficient quantity of water that in most situations will require only occasional refilling.

3L (102 fl. oz.): Made for the thirstiest of riders, people disinclined to stop for refills or anyone exploring terrain where water is scarce. Since a liter of water weighs approximately 2 pounds (0.9 kilograms), the potential drawbacks of toting a 3L reservoir (weight and bulk) are fairly obvious. Yet a 3L reservoir offers excellent versatility. To keep weight low on shorter trips, carry only the amount of water you anticipate needing. Then, on the occasions when you need the full 3L capacity, it's available to you.

Size of the Opening

CamelBak reservoirs sized 1L or larger offer a 3.5-inch opening. (A few CamelBak hydration waistpacks use reservoirs smaller than 1L.) This extra-wide opening makes it easy to drop in ice cubes, and many people can fit a hand through the hole to better clean the reservoir's interior. Reservoirs from MSR use a 63mm (2.5-inch) opening, which matches the screw-on (no-spill) threads of all MSR water filters.

How Much Water Should You Drink?

CamelBak recommends 1 liter of water for every hour of activity. Yet any number of factors (temperature, elevation, personal health, activity intensity) could impact a person's hydration needs.

In 2004, the Food and Nutrition Board of the nonprofit Institute for Medicine (part of the National Academy of Sciences) released a report on the recommended intake of water (and some minerals). While exact water requirements were not specified, general daily recommendations for women were set at 2.7L (91 fl. oz.) and 3.7L (125 fl. oz.) for men. This figure includes "total water"—water derived from all beverages and foods. About 20% of a human's daily water intake comes from foods. Exercise intensity and high temperatures clearly will increase a person's daily water needs.

Excessive water intake can actually be life-threatening. But by far the greater risk facing active outdoor athletes is under-hydration and dehydration.

Play it smart. Step up your awareness of body signals when active outdoors, particularly if the intensity, temperature or elevation is higher than normal for you. Drink fluids regularly and generously, even before your thirst-alert mechanism kicks in. Using a hydration system gives you an advantage. Because fluids are so easy to access, you'll drink more often and as a result perform better.

Consider Cargo Capacity

Cargo space in hydration packs varies by intended use.

The largest backpacking/hiking packs offer close to 2,500 cubic inches (41L) of cargo room and offer enough comfort and load-support features to perform well on light-and-fast overnight adventures. Other hiking/climbing packs are in the 1,800 cu. in. (29L) range and are well-suited for all-day activities.

Mountain bike hydration packs are a little smaller, with cargo space ranging from 1,400 cu. in. (or 23L, enough for all-day rides) to 100 cu. in. (3L, just enough room to carry a spare tube, CO2 cartridge, wallet and an energy bar).

It's essentially the same story for snowboarders and skiers. Some people want extra cargo room as a stash spot for extra clothing layers. Others want the smallest pack possible so they can wear it under a jacket and use body warmth to keep liquids unfrozen.

Road bike hydration packs and trail-runner waistpacks tend to be the smallest of the group. The reason: Hydration packs, originally created for cyclists, are meant to carry lightly on a person's back and generate minimal wind resistance.

Get a Good Fit

Bigger is not necessarily better. Lots of cargo capacity can be valuable to a mountain bike daredevil who needs a stash spot for a full-face helmet or other protective gear. Most recreational riders, though, usually don't need that much space—just enough room for a stuffable jacket, a tool or two, a spare tube, snacks, sunglasses and a few other toss-ins. A bigger pack is less aerodynamically efficient. Stuff too much into it and it might even ride up your back and bump your helmet. So be realistic about your personal style when eyeballing pack options.

Stability. Smaller packs will be more stable on your back. Envision a pack when it's fully loaded and how it will ride on your back. If you anticipate carrying large loads, look for a waistbelt.

Organization. Run through a mental inventory of the gear you carry on a ride that you consider routine. Visualize how your customary gear assortment can fit into a pack's pockets and compartments. (This is easier to do in a store than online, obviously.) Can the pack accommodate your favorite jacket? Does it offer a pocket where a potentially gunked-up tool can be isolated from other items? Does it provide enough snack space for the length of trips you typically ride?

Women's and kids' models. A number of packs are engineered to provide an enhanced fit for a women's physiology or a younger person's smaller frame.

Sip Tubes and Bite Valves

Sip Tubes

All brands offered at REI use tubes constructed out of polyurethane. It's a durable material that also "drapes" nicely. Rarely, if ever, will you find your tube in a tangle of kinks.

Polyurethane, though, can transfer some taste of plastic to the water. To minimize this, make a diligent effort after every trip to ensure the tube's interior dries completely. If it's detachable from the pack, disconnect the tube and shake out all the water that you can. If it is permanently connected to the pack, examine the valve and see if it is detachable. If so, remove it and shake all of the water you can from the tube's interior.

Direct exposure to sunlight for a limited length of time can help dry a tube, though try to avoid selecting an incessantly sunny spot where heat can build up and cook the tube. Instead, seek a well-ventilated location.

Bite Valves

Silicone is a commonly used material. Modest tooth pressure, not a big chomp, is usually all that is needed to get water flowing. Some people routinely bite too hard on their valves and hastily wear them out. Our sales staff has heard that bite valves that twist on and off, or that have an on/off switch, are less prone to leakage.

Bite valves seem to be an area of hydration systems most vulnerable to leaks—not surprising since they get most of the action. It is not uncommon to need to replace a bite valve once or twice in the lifetime of a hydration system.

Other Components

Tube portals: This is a slit (or slits) that allow your sip tube to easily thread the sip tube from the reservoir inside the pack to the exterior. Many packs offer 2 portals so you can position the tube to hang over either shoulder. Some packs offer a single, centered portal. You may find a pack that has 1 portal on 1 side of the pack. If you have a strong preference where your tube hangs, choose a pack with a portal system suited to your wishes.

Clips: Looking for a way to keep your tube positioned for easy access? CamelBak offers accessories such as the CamelClip, Tube Director and Tube Trap.

Cold weather add-ons: As mentioned earlier, assorted winterized add-ons are available, including insulated sip tubes, insulated reservoirs, reservoir covers and bite valve covers. They can be handy, though they add a little bulk and weight to your system.

Usage Tips

Frigid weather: 1) Fill the reservoir with warm water to resist freezing. 2) Routinely perform a "blow back" in your sip tube when you've finished a water break. If you push water out of the tube and back into the reservoir, water can't linger in the tube and freeze.

Hot weather: It is OK to freeze a reservoir and its contents. Just be sure to leave room (perhaps one-quarter of the reservoir's capacity) for the liquid to expand as it solidifies. Do not fill the reservoir to the brim and then attempt to freeze it. If you do and then seal the reservoir, it could potentially burst. You can also use an insulated reservoir and tube to preserve the temperature of cold water on hot days.

Cleaning and Storage

Cleaning kits, tabs and dryers offered by CamelBak and other reservoir-makers provide handy ways to maintain a reservoir and sustain its life.

When a trip is complete, a reservoir and sip tube should be emptied as soon as possible and allowed to air out and dry. The crew at Cascade Designs (maker of Platypus and MSR Dromedary, Hydromedary and Cloudliner reservoirs) offers the following tip for keeping reservoirs and tubing fresh and taste-free:

• Mix 1 or 2 cups of baking soda with 2 or 3 quarts of water.
• Squeeze half a lemon into that mixture, pour it into a reservoir and let it sit for 1 or 2 days.
• Empty the reservoir, rinse it very thoroughly and prop it open it so it can dry fully. (Commercial drying kits are particularly handy for this.)
• Some of that mixture can also be used to soak a sip tube to restore its freshness. Another option: Soak the tube in a mild bleach solution. Either way, afterward rinse and dry the tube thoroughly.

Like a tent, ensuring that a reservoir dries completely is critical for avoiding mildew growth.

If you use flavored drinks or sports drinks in a reservoir, it can be close to impossible to totally remove every hint of an introduced flavor from a reservoir. The baking soda/lemon treatment described above gives you an above-average chance to succeed.

Avoid using iodine to treat water in a reservoir. Typically, the taste of iodine will linger in the plastic forever. Chlorine dioxide tablets will likely also leave a trace of taste, just one not as blatantly noticeable (and distasteful) as iodine.

When storing a completely dry reservoir, do not fold it. Allow it to lie flat or, if possible, keep it propped open. Creasing the material may spawn cracks in the future as the material ages.

Tech Talk: Reservoir Materials

Good news: All hydration reservoirs offered at REI, whether sold separately or included in a hydration pack, are BPA-free. BPA is shorthand for bisphenol A, a chemical that made news in early 2008. BPA is used to create polycarbonate plastic, and for years polycarbonate water bottles were a popular choice for their clarity, rigidity and virtual indestructibility.

REI stopped carrying these bottles when a 2008 report by the National Toxicology Center, part of the federal National Institutes of Health, raised health questions about BPA. An ongoing debate surrounds those questions.

BPA's chief attribute is its ability to create rigidity in plastic, and hydration reservoirs are soft and pliable. So rest assured—you'll find no BPA in hydration reservoirs. So what is used to create reservoirs? While not every reader will want to know about reservoirs to this level of detail, we offer information provided by manufacturers to present a technical look at some brands carried at REI.

CamelBak: All reservoirs are made with multilayer polyurethane (PU). The outer layer is "ruggedized" (a CamelBak term) to optimize burst resistance. The inner layer is impregnated with an FDA-approved silver ion compound that the company calls HydroGuard Antimicrobial Technology. Since the compound is embedded into the inner PU layer, CamelBak states that it will not wear out or peel away. The same antimicrobial compound is impregnated into all CamelBak PU sip tubes.

MSR CloudLiner and Hydromedary reservoirs: Food-grade polyurethane makes contact with the water in both styles. The key difference between the two? Hydromedary reservoirs are bonded to a 200-denier Cordura© nylon for enhanced abrasion resistance. Accordingly, Hydromedary reservoirs weigh about 1 ounce more than same-size CloudLiners. Polyurethane, which is also used in the sip tubes, can transfer some plastic taste to water, particularly if stored for a prolonged time or is exposed to sustained heat or sun. Any transfer of a plastic taste can be minimized by keeping reservoirs (and tubes) dry.

MSR Dromedary and Drom-Lite bags for water storage: Both are polyurethane-lined, so the plastic taste precaution noted above applies here. (Keep them dry when in storage.) Drom-Lite bags offer the same construction as Hydromedary reservoirs, with 200-denier nylon exteriors. Dromedary bags, designed for very rugged use (popular among climbers), feature 500-denier exteriors—except the 10-liter model, which uses a 1,000-denier exterior. The 63mm openings of all MSR reservoirs and storage bags are compatible with MSR water filter threads. An MSR hydration kit is available to transform any Drom bag into a hydration system. MSR also offers a shower kit or a spigot cap that works with any of its reservoirs/bags.

Platypus: These reservoirs (and storage containers) use a thermoplastic polyurethane (TPU) exterior bonded to a polyethylene (PE) interior. The interior also includes a thin layer of metallocene ultralow low-density polyethylene (LLDPE), which contacts the water. Metallocene LLDPE is a high-grade material used in food packaging, such as packaged salad greens found in grocery stores (though it's a thicker, much more durable variety of the material than used for salads). It transfers virtually no plastic taste to water and is embedded with an antimicrobial silver ion compound. The sip tube uses polyurethane, which can transfer some plasticity. (Minimize this risk by keeping the tube dry.) The TPU exterior gives Platypus reservoirs a slightly stiffer texture, which can make them easier to slip in and out of a pack's reservoir sleeve.