How Much Water Do You Need When Trail Running?

By David Hoang

As the weather warms up and nature starts to flourish, you may want to spend some time on the trails. But before we pounce on the great outdoors, we need to plan for one thing—hydration.

Drink plenty of water before, during and after a trail run.
Staying hydrated is key to being able to exert yourself physically outdoors.

Your most important concern should be water. After all, it makes up 60% of our total body weight. Staying hydrated is key to being able to exert yourself physically outdoors. It can be dangerous if your water levels are low.

It is important to weigh yourself before working out. When your body is trying to cool off, you sweat. Since our bodies are primarily made up of water, we need to replenish this lost “water weight” when we exercise. How much you need to drink will depend on how long you’re on the trail for.


Drink 20 fl. oz. 2 hours before you exercise. This is a little bit more than a 16 fl. oz. standard water bottle. This is important because it gives your body time to absorb the water to hydrate your body before undergoing physical activity.

Hydrate While on the Trail

Use a 12 Survivors personal water filter straw to procure safe drinking water while on the trail.
While on the trail, drink 20 fl. oz. of water for every 15-20 minutes of hiking or running.

Drink 10 fl. oz. for every 15-20 minutes. This is about 2 or 3 mouthfuls of water.


After exercise, hydrating is crucial to getting back to normal fluid levels. It is recommended you drink 24 fl. oz of water for every pound lost while active.

An important factor to consider when planning a day on the trail is the altitude. The higher you go, the more dangerous it can be. At high altitudes, you have increased urination along with increased heart and respiration rates. This can be a deadly combo if not accounted for.  You will need to drink more water in this environment to stay safe.

While it is great that we know some good hydration practices, what about dehydration?

There are some early indicators that you need to watch for while on the trail. Early detection can make or break a day running trails.

Early signs of dehydration include:

  • Dry mouth—If you are feeling dryness in your mouth, dehydration has already begun.
  • A decrease in energy—Fluid loss causes your heart to work harder to put oxygen and nutrients into the bloodstream. This can cause fatigue.

Serious Symptoms:

  • Cramps—You need water to move your muscles. If you don’t have enough water, your muscles are weakened.
  • Dark urine—The darker your urine, the more dehydrated you are.

Don’t worry though; the cure to these ailments is simple.

Drink more water.

How Much Water to Carry on the Trail

Drink 10 fl. oz. of water for every 15-20 minutes of activity while on the trail. Use the 12 Survivors Pocket Water Filter Straw to drink safely directly from the source
Drink 10 fl. oz. of water for every 15-20 minutes of activity while on the trail.

Water is heavy! Your standard 16 fl. oz. of water weighs just a bit over a pound, so if you want to avoid carrying extra weight while you run, plan a route that will have safe sources of water so you can refill your water bottle. If you are unsure about water quality, you could use a water purification system. They can be small enough to fit in your pocket or large enough to filter enough water for the whole team. These devices can quickly turn murky water into an oasis. However, with size comes longer filter times. Alternatively, you could also pack hydration bags and skip filters altogether. The advantage of this is you can hydrate without having to stop. 

How do you stay hydrated on the trail? Tell us in the comment section.

About David

David is an Arlington, Texas native who is an advocate in the local Vietnamese Community. He strives to promote culture and preserving traditions. Over the years David has gained strong volunteer experience and community involvement. In his free time, he enjoys learning about history and spending time outdoors.