(Un)Packing Hydration Vests

Posted on 25/04/2019

Author: Andrew Hagen is an Altra ultra runner who recently finished the Daigonale des fous 100 miler in a time of 37:30, mental. He is an avid mountain man and photographer with a deep understanding of nature and you can find him on any given morning snapping photos of the majestic mountains.  

One of the great things about running is that it’s a simple sport. You hardly need any gear at all to get started. But when you sign up for a big race, take your running further into the mountains, or just go self-sufficient for a few hours, then you’ll probably need to add a few critical items. What items you need to carry will determine what running pack (aka hydration vest) you choose, so in this article we’ll dive into a few common use cases and the sort of packs that work best.

Choosing a Hydration Vest

Do you need a vest at all? If all you need to carry is a phone, a windbreaker, some gels and up to 1 litre of water, then you could get by just fine with a running belt, or handheld bottle holster. It’s not always a question of how far you are running, but more a question of how far away from support you’ll be. Enter a long-distance mountain race, and you’ll most likely be required to carry emergency gear, and then a running pack will be essential.

The most popular running packs on the market range from 5 to 13 litres. On the larger end, you’re buying a bag that can be used for all sorts of things in all sorts of conditions, while the smaller bags are less versatile but allow you to get your racing weight down to the bare minimum.

What you can fit into an 11-litre pack without being overloaded (you could probably squeeze all that into about 8 litres, but its probably not ideal)

How many litres do you need?

5 Litres

Sign up for a high-profile race and you’ll see quite a few lean racing snakes wearing 5-litre race vests. These are about the minimum size that can still accommodate a fairly comprehensive kit, which typically includes:

  • Lightweight waterproof jacket
  • Thermal base layer
  • Beanie
  • Space blanket
  • Basic first aid kit
  • 1 litre of water
  • Race nutrition

The trouble is, not everybody has a lightweight waterproof jacket or a compact thermal top, and some might want to carry solid food or more than a litre of water, and perhaps poles, and so on. A typical single-layer hiking waterproof takes up three times the volume and weight of a specialised running jacket, like the Ultra Jacket from Ultimate Direction. If you wear large sizes, then your problem is compounded.

The 5 litre packs that are currently available are made mainly of stretch mesh, and your gear is stored in elasticated pouches. An advantage of this design is that the pack fits snugly around your body, and you can reach back and stuff items away without fumbling for a zip. Another plus is weight-saving – these bags come in below 200g. If you already own compact running kit, and you don’t plan on long missions in potentially wild conditions, then a 5-litre pack could be ideal for you.

The disadvantage of a small pack made of stretch mesh is that you can easily overload it – or unbalance it by not distributing the weight just right – and then it could bounce and move around. If you’ll frequently be pushing your pack to its storage limits, then you’re probably better off with a larger pack.

8 – 12 Litres

Next up, we have packs ranging from 8 to 12 litres. The extra litres are not the only difference, but for a start, the increased volume gives you room to pack a warmer fleece and a camera, or just arrange things with more freedom. There will be occasions when you might want to carry more than a litre of water, so having a little more room on the back means that you can fit in a reservoir or an extra bottle.

I’ve raced up to 100km with a 7-litre pack, and more recently an 11-litre (UD Jurek FKT Vest), and while the 7-litre bag didn’t technically limit me, the 11-litre has made my life far easier, and volume is not the only reason why. In this size range there are a variety of designs available, and a feature I personally like is a long zip that goes part of the way around the bag. This allows you to flip the bag open and reach items at the bottom without repacking each thing sequentially, as you might have to do with a smaller opening. It also makes it easier to position awkwardly-shaped items such as headlamps away from your back, and if you use a reservoir then it makes it far easier to pack large clothing items. Other handy features to look out for are waterproof compartments, dedicated cell phone pockets and attachment loops that allow you to carry trekking poles. If you enter a race like the 170km UTMB, you’ll need to pack a very comprehensive mandatory kit, including things like waterproof pants and spare headlamps, and an 11- or 12-litre bag will probably be perfect. I’ve used my 11-litre UD vest for a similar race with slightly less kit (Diagonale des Fous), and it worked brilliantly since it was never a hassle to repack it at aid stations. Back home, I like having the room to carry a proper camera in my running pack.

A relevant question is how well a bag runs when you only have a few items in it. Most 10+ litre packs come with elastic cords to cinch the pack down when it is not full, and some allow you to make multiple adjustments to tighten the fit (sternum and sides). The worst situation is probably to have water bottles on the front with almost nothing in the back, but if you get a pack that fits you well and has a range of adjustment, you can make this work.

10 or 11 litre bags with lots of separate pockets and zips do come with a weight penalty, but at 200-300g (excluding bottles), I wouldn’t be too put off. If, however, you are looking for a super lightweight pack, the Halo Vest from Ultimate Direction is an 11-litre pack (or 10-litre in the women’s model) weighing under 200g. This pack is designed with stretch mesh and “kangaroo pouches”, a lot like the 5 litre bags discussed earlier, so it comes with similar advantages such as being able to stuff items into the back while running. These bags should be on your shortlist if you are primarily concerned with running and racing. If you want to use the pack for recreational mountain missions and hiking, I’d recommend the other styles with the extra zips and loops.

13 Litres and Up

Taking these concepts further, we have 13-litre packs. Here again we see more mountaineering features, allowing you to add things like ice-axes, and the extra volume accommodates more warm layers. We have splash-proof ripstop fabrics and external loops and cords. If you like to do light and fast missions into the Natal Drakensberg in winter, then this sort of bag will suit you well. A 13-litre pack is about as big as you can currently go without compromising your ability to race. In other words, this is about the biggest pack that can still be cinched down to fit snugly against your body for running. You can get bigger packs in the 15 to 20 litre range, but you’ll be losing the focus on running and moving toward hiking and climbing use cases.

Other Considerations

Ticking all the boxes on paper is great, but before you part with your money, I’d advise taking your typical racing kit to the store and try packing it into a hydration vest. This will give you an idea of how well the different styles fit you, and how easily you can access your gear. Try getting stuff in or out of the front pockets with bottles or flasks installed, and see if you can reach the side pockets, or whether you’d rather have no side pockets for more freedom of arm swing. Think about where you’ll keep your gels and bars, and where you’ll stuff the wrappers after you’ve eaten them. Can you run for a couple of hours without having to slip the bag off your shoulder? Do you want a pouch on the front for your phone? Do you need a rain cover or waterproof compartments? Can you fit in a fleece as well as a reservoir?

Another decision to be made is how you’ll store your water. Just about any hydration vest will accommodate a 1.5-litre reservoir, and most offer bottles or soft flasks on the front. Bottles are simple and exchangeable so that you can swap them easily at aid stations, while soft flasks reduce sloshing noises and might be preferable if bottles give you pressure points on your chest. The downside of soft flasks can be their custom size, or a little more difficulty in fitting them back into their pockets. Take note of water capacity in the context of how much you think you’ll need between aid stations at races.

Different brands have different sternum adjustment systems, and some even allow you to adjust the side straps on the run. Some models are unisex, and others come in gender-specific styles. Make sure that your pack doesn’t chafe your neck or pressurise your chest too much. Once you’ve bought your bag, learn how to set it up for different loads so you don’t have to faff with it on race day. Personally, I’d advise you not to use weight as your main deciding factor – comfort and convenience may affect your performance and enjoyment more than the 100g or so that separates the different models in the range.

In Summary

In summary:

  • For non-extreme trail and road running, or races in climates where you don’t need multiple clothing layers, a 5-litre bag will do well.
  • For a typical Western Cape mountain run where a fleece and rain jacket are essential, or for an ultra in a mild climate, go for a pack that holds upwards of 8 litres.
  • Planning to do UTMB or Skyrun, or need a multi-purpose pack? Get at least a 10-litre bag, so you can squeeze in your waterproof pants and gloves, and maybe something more substantial to eat than gels.

Ultimately, we’re spoilt for choice these days, so find the pack that works for you, and get out there and enjoy the adventure!

We are all about community here at RUN, so let us know what your favourite go to Hydration Vest is in the comments below!

Leave a Reply