Hydration is one of the most common questions around trail running, but as a hiker rather than a trail runner, I wanted expert advice from those who work with trail runners every day. I asked the team at Bogong Equipment to share their guidance on how much water to carry when trail running, based on real-world experience across a wide range of conditions.
How much water should I carry?
The answer, of course, varies. How much water you carry on a trail run depends on many factors, including…
- the distance you plan on running
- the availability of water on your route
- how remote the trail is
- your level of conditioning
- how warm it is
- your size and weight
- and more.
It may be tempting to carry more water than you need. But, this means you’ll be running with a lot of extra weight, which isn’t practical or wise.
My advice is, think logically. Examine the run you intend to do. What water sources are available? How warm is it? Are you bigger or smaller? Water requirements can vary according to the size of a person.
Road runners are used to regular aid stations and shorter distances or lengths of time running. So, it can be confusing knowing how much water to take, whether you’re doing a 20K training run or a big trail event.
To guide you, we’ve outlined four scenarios.
- 6K easy, well-trafficked trail
- 21K trail running event
- Bush run
- Advanced ultra event
6k easy, well-trafficked trail
For a short, easy trail run in a well-trafficked or urban environment, such as Yarra Bend Park, hydration needs will vary between individuals and conditions.
Some experienced runners may complete a short run without carrying water in cool conditions, but this should not be assumed to be safe for everyone. Heat, humidity, pace, terrain, and individual sweat rate can significantly increase fluid needs, even on relatively short runs.
If you are new to trail running, running in warm conditions, or unsure how your body responds, carrying a small bottle or handheld flask is a sensible precaution. Even experienced runners should consider carrying water if conditions are warm or if the run may take longer than expected.
A useful strategy in familiar areas is to run loops that return to a known water source, such as a car or public tap, which reduces the need to carry larger volumes while still allowing regular hydration.
21k, trail running event
Trail running events commonly have aid stations along the course. This means that you’ll only need to carry as much water as you think you’ll need between aid stations.
As an example, when I ran the Surf Coast Century 50K, I carried 1L between aid stations. There was an aid station at the halfway point. There, I refilled my hydration bladder to carry another 1L for the second half of the race. Again, this isn’t a hard-and-fast rule. I felt that this amount of water was as much as I – specifically – needed. A lighter, or heavier, or less- or more-conditioned runner might need to carry a different amount.
At organised events, the higher the participant numbers, the more support tends to be put in place. Obviously, if there are more aid stations, you can carry less water.
We recommend: Salomon Advanced Skin 5 Hydro Set
Also consider: Ultimate Direction Ultra Vesta Women’s Hydration Vest, Ultimate Direction SJ Ultra Vest 3.0
Bush run
Water tanks and creeks are sources of water on a remote bush run. I carry water purification tablets for added safety. I might not use them, but I’ve got them as an option. They come in handy if I’m fatigued, didn’t bring enough water, or I’m out for longer than I thought.
If I was running in a rugged park like Lerderderg State Park or similar, there’s a good chance that nobody would pass me for at least half a day or even more. In this situation, I carry extras, like a survival blanket, mobile phone and extra water.
We recommend: Katadyn Micropur Forte Tablet
Advanced ultra events
Mountain races are an example of a situation where managing fluids and fuel intake is essential. Creeks and water tanks at huts may help, but they can’t always be fully relied upon. For example, at the Razorback Run in 2013, I set off with 2.5 litres of water and sports drink. The course shoots straight up Mt Feathertop, then drops down to Diamantina Spur. By that time, you’ve been running for 2.5 hours, minimum. Then you run up, over the High Plains (and there’s no water there), all the way across to Cobungra Gap. That’s perhaps another hour. By the time you reach an aid station, you’ve done 40 kilometres, 3000 metres of ascent, and been out for five to six hours running in not much shade. When I ran it, the temperature was in the high 20s!
We recommend: Salomon Advanced Skin 12 Hydro Set
Also consider: Ulimate Direction PB Adventure Vest 3.0, Ulimate Direction AK Mountain Vest 3.0
In summary, consider all the elements. Make an educated decision on how much water you need to carry, based on the remoteness of your run, your fitness level and what water is available where you’re running.
Also, it’s better to think in time, not distances. A 6K hilly, rugged bush run takes a vastly different amount of time to running a relatively flat 6K on wide, heavily maintained trails. It’s wise to wear a good watch when you’re out on the trails. Not only can you keep track of time, but many watches out there should be able to record distance, elevation and even GPS location.
Foot note: Train and practice. The more time you have with your gear and testing hydration methods, the better tuned you’ll be to your body’s requirements for whatever distance you plan to do.
In summary
In summary, hydration needs for trail running depend on time on feet, conditions, terrain, and individual factors rather than distance alone. Carrying too little water can quickly become a safety issue, particularly on hot days or in remote areas, while carrying excessive weight can negatively impact performance.
Think in terms of time, exposure, and remoteness, not just kilometres. A short but steep or technical run can take far longer and place greater demands on hydration than an easy, flat route.
Training with your hydration setup and practising different strategies will help you understand what works best for your body and the conditions you commonly run in.
Author: Stephen Upton
Contributed by Bogong Equipment
