Belt, pack, or handheld? Bladder, collapsible bottle, or recyclable cup? Which is your preferred hydration item to use while trail running? In trail and ultrarunning, the various vessels used to hold water or other hydration beverages (electrolyte mixtures, sodas, etc.) all come with their own unique pros, cons, or specializations for certain circumstances.
Runners are often passionate about their choice of hydration vessel, much in the same way runners are passionate about their footwear and apparel choices. While personal preferences are certainly a factor, this article explores the specific circumstances where particular hydration vessels are most or least useful.
Why do hydration vessels matter in trail and ultra running races?
With shorter track, road, and cross country running races (10km distances and below), it’s rare to see runners carrying fluids. With the short duration of running time for these distances (typically less than 1 hour for most runners), there is no need to carry hydration during the race as long as runners remember to hydrate well before and after the race.
These courses may also offer aid stations at certain checkpoints along the course that provide water, electrolytes, or sports nutrition snacks such as energy bars and fruit. Aid stations and start/finish line areas have medical professionals or race volunteers/staff who can help with symptoms of dehydration before the condition becomes life-threatening. Additionally, most of these races are held in urban areas where there is immediate access to water and other basic resources, meaning that even in the case of an extreme emergency where runners get lost or become seriously dehydrated, medical help is never far away. Competing in shorter road, track, or cross country races is typically safe in terms of dehydration risk unless the temperatures soar and the heat index is deemed unsafe for exercise.
Filling up a bottle at Bears Ears Ultra.
In trail and ultrarunning, however, hydration should be a major focus for athletes and be planned accordingly. Runners should expect to be more self-sufficient with their hydration, even in shorter (10km or less) events. While most trail races have aid stations similar to road or cross country events, these aid stations are typically spread out in distance and, thus, spread out in terms of time between aid. This is often due to limited vehicle access on trails, especially with trail races held deep in mountainous terrain or forest lands. This limits an event’s ability to provide support to runners along the course. If runners become lost or experience symptoms of dehydration, it may be extremely difficult for assistance to arrive in a timely manner. Something as simple as rolling an ankle or getting lost can drastically increase the predicted amount of time spent between aid stations without access to fluids. In harsher desert or high-altitude environments, this can be race-ending and potentially life-threatening.
Should I train with hydration vessels?
What you plan to do in a race should first be tested in training. This rule applies to many things, such as not wearing a pair of brand new shoes out of the box for the first time in a race, but is especially important with hydration vessels. There are pros, cons, or specific uses to every type of hydration vessel, as well as personal preferences that have to do with the exact fit or what feels most comfortable. If you choose to train with hydration vessels, you will gain the advantage of having the opportunity to test products and find those most optimal for the specific challenges of your event. Even if training runs less than an hour, carrying hydration is a good idea, especially when exploring trails in new areas where you might be more prone to getting lost. Due to the lack of aid stations on training runs, you might find yourself wearing/carrying even more hydration during training than in actual races!
PROTIP: Contrary to the popular belief that training without water is “macho” and makes you a tougher runner who requires less water than other runners, it actually makes you slower. This is because runners perform better with more hydration, as well as recover more quickly from workouts. Training without water only inhibits performance, increases the risk of injury, or impairs future running sessions, sleep, and recovery.
Belt, pack, and handheld breakdowns
The most common hydration vessels used in trail running are belts, packs, and handhelds. See the results of the annual American Trail Running Association Spring survey to learn more about runners’ hydration choices in 2024. (scroll to the Running shoes, poles, coaches, and hydration section)
Listed below are the top three hydration vessels described in more detail with a list of their top pros and cons:
Camille Herron with a hydration belt and handheld bottle.
Belt
Running belts are one of the most common running accessories used to carry loose items such as keys, wallets, and phones or to attach hydration vessels such as bottles. Some are more hydration-specific and come with their own lightweight plastic bottles for fluids.
- Pros: The location around the waist is closest to the runner’s center of mass, giving the belt the advantage of being the most efficient way to carry extra weight by using the runner’s hip instead of back or arm muscles. Belts come in a variety of sizes and fabric types to customize the fit and decide what’s best for particular racing environments. They allow the hands to be free while running, and most have easy accessibility to stored items.
- Cons: Many waist belts are not designed to carry large amounts of fluid and racing gear. This means that for longer runs and races, you will be more reliant on aid stations or forced to wear a pack in addition to a belt. Some belt fabrics do not have a secure fit and cause chafing or bouncing issues, particularly when running at higher speeds.
- Average Price: $15-50
- PRO Qs: How does the belt feel when it’s empty versus full? How secure are your bottles when running downhill or at higher speeds? Does the belt shift position up or down on your waist while running? How easily do the zippers zip and unzip?
Mike Foote wearing a hydration vest.
Pack
A running pack is typically a backpack-like vest that contains a built-in fluid reservoir (or bladder) or has pockets to hold collapsible or solid plastic hydration bottles. In contrast to a traditional hiking pack (which I’ve seen some trail runners use, though it is typically not an ideal choice), materials are lighter, fabrics are more sweat-wicking, and the size and fit are designed for the motions of running as opposed to trekking. Most packs have clips that tighten around the chest or waist to better distribute the pack’s weight and secure the fit. Trail running packs come in many types, such as those for “fast packing” (ultralight, shorter duration backpacking completed by trail running as opposed to hiking) or others for different durations of racing and training without the need for overnight sleeping and cooking gear.
- Pros: Packs have the potential to carry the most fluids of the three options listed. Runners can go for hours without worrying about running out of fluid or needing to stop and refill. This saves runners time at aid stations, as well as gives the potential for longer, better-hydrated adventures through even the driest and hottest of conditions. Packs are required for many long ultramarathons, so getting used to using them is essential for runners interested in 50-mile-plus distance ultramarathons.
- Cons: They are by far the heaviest of the three options. The additional amount of material from a pack, as compared to a belt or handheld, can also increase sweat rate, cause chafing, or be the most uncomfortable to feel while running. Some packs are not designed specifically for women, which is another common complaint of packs for female runners.
- Average Price: $80-200
- Pro Qs: If your pack has a built-in reservoir, where does the hose rest? Does it bounce? How easily can you access items on your back? Are there considerations for breathability on the back and shoulders? Do you have the potential to store items on the side and not just the back of the pack? How quickly can you take the pack on and off and refill it? How easily can your hydration reservoir be cleaned?
Handheld
A hard or soft/collapsible bottle, typically plastic, that is designed to be carried by hand while running. The shape is designed for the running motion, while allowing the hand to be relaxed. This is typically achieved through utilizing a strap that secures the bottle to the runners’ hands. While some runners choose to use an empty plastic water or sports drink bottle, these bottles are not designed to be carried while running and typically fatigue runners’ grip muscles, particularly over long distances. The bottles referred to in this article are those specifically designed for running. Some handhelds may also have zippered pouches to carry wallets, keys, or small snacks and electrolyte packets.
- Pros: The lightest and most affordable hydration option. They also have a low risk of chafing (only between fingers), and have little risk of bouncing. Hydration is easily accessible, and most are designed to be squeezed by mouth to open and close.
- Cons: In terms of running economy, carrying extra weight in your hands is extremely inefficient. Additionally, most bottles don’t carry enough fluids for long runs, requiring runners to stop often to refill. Some bottles feel uncomfortable when only halfway full, and you can feel and hear the jostling of the fluids more than with the other vessels.
- Average Price: $10-30
- Pro Qs: Does the bottle have a top or cover that gets in the way of opening it quickly? Does the bottle have a curved shape that encourages a relaxed carrying motion? How easily can you undo the top to refill? Does the bottle leak, or is it difficult to close?
Emily Hawgood with a hydration vest at Western States 100.
How do I choose the hydration vessel(s) that best suits my needs?
There are several factors that greatly impact hydration vessel choice: distance/time, climate, terrain, race-specific regulations, and fit. I’ve listed below the pros and cons of the major hydration vessels, considering each of these factors.
Distance/Time
As a general rule, the longer the distance you are running, the more capacity for fluids you should be able to carry. Packs are the ideal choice for carrying the most possible fluids comfortably, with up to 15 plus liter reservoirs offered by many of the top pack brands for ultrarunning, such as Camelbak, Osprey, Nathan, or Salomon. One major exception to this rule is if your running route is looped or you are in a race situation where you are certain that the distance and time spent between aid stations is small enough that you can comfortably carry your fluids in smaller, lighter vessels. For short-distance races, handheld bottles or waist belts might be preferable to packs as they are often lighter and will produce as much sweat (a common complaint of packs is the sweat on runners’ backs). Wasitblets and handhelds also typically have less risk of chafing.
Climate
Temperature, wind speed, altitude, sun exposure, and humidity are all major environmental factors that should be considered with regard to hydration needs. Hotter temperatures, stronger winds, more sun exposure, and higher altitudes all increase hydration needs. Interestingly, humidity and lack of humidity are both dangerous. In humid conditions it is more difficult for sweat on the body to evaporate and cool the body, while in low humidity (dry environments) fluid demands increase as moisture is drawn directly from the skin or while you breathe. If your training or racing takes place in any of these extreme climate conditions, you should be especially attuned to your hydration needs. The more extreme the climate, the more likely I would choose a pack or belt as opposed to a handheld hydration bottle. This is because I’ll be better able to carry more fluids and have more space to have other products I might need, such as sunscreen, snacks, extra electrolyte mixes, etc., to deal with tougher climates.
Anita Rai at Fishtail 100.
Terrain
Terrain is an important factor to consider because you will be running at different speeds and carrying your body weight (and those hydration vessels attached to your body) in different ways based on the terrain. For example, when running on flatter trails, you’ll be able to run at higher speeds and may prefer a handheld bottle or belt over a pack to reduce the amount of bouncing from the pack on your back. In contrast, if your race is on technical mountainous terrain (such as the Hardrock 100), you might not need to worry about the pack bouncing and might prefer its ability to carry more fluids and more easily have the ability to search through it at slower speeds that might not be able to be achieved at high speeds. For skyrunning races, you might prefer a pack or belt over a handheld to keep your hands free for scrambling and climbing sections.
Race Regulations
Races may require specific hydration vessels for all participants. Others will likely have recommended gear lists, which should also be considered. For shorter races or races in less extreme environments, a handheld bottle or belt may be sufficient to meet basic requirements such as the capacity to carry a minimum fluid of liters or ounces. For longer races, specifically 50 mile or longer trail ultramarathons, gear requirements may include a running pack, potentially with a reservoir, to meet much larger fluid needs. These rules stem from the safety concerns of trail running and are taken seriously at many events, particularly those in Europe. For an example, see the extensive gear list and hydration requirements for the prestigious UTMB race here.
Runners line up at the Pikes Peak Marathon. Photo Credit: Peter Maksimow
Fit
In terms of fit, all three of the major hydration vessels should feel comfortable and fit a variety of body types. The pack, however, may be the most difficult to find an individualized fit as torso, shoulder, and height (as well as gender) must all be considered. Belts and handhelds are more easily adjustable for a wider variety of body types. If you have trouble fitting any particular hydration vessel, consider switching to another size and/or model/brand with different fabrics, strap designs, and weight distribution. Also, remember that even if a hydration vessel fits well in the store, it will fit differently when you’ve loaded it with fluids and other items. Make sure to test your hydration vessel with all of your essential racing gear to make sure it’s the proper item for your racing needs!
Curious to learn more about hydration? Check out our article How To Hydrate for Trail Running in All Seasons.
PROTIP: Consider hydration vessels with built-in filtration systems. This will allow you to fill up bottles from natural sources such as mountain streams and rivers, reducing reliance on aid stations or needing to carry all of your own fluids. Adventure longer, with less weight, and ensure you’re drinking clean water free of microplastics, bacteria, or parasites with the following filtration systems:
Filter Cap by HydraPak (can be used on most HydraPak bottles)
