Should I drink water while running?

Runner drinking

Learning how to hydrate correctly is one of the skills I’ve had to learn in my own running journey. Runners often wonder when to drink water while running, but a lot depends on the distance you’re planning.

For runs under 5 miles, you want to drink 6 ounces (170g) of water at least 30 minutes before your run. For a run that is longer than 5 miles or longer than 30 minutes, you want to take a little bit of water with you. Do not overindulge in the water while running; instead, take a big sip at scheduled intervals. 

I’ve experienced both ends of the hydration spectrum. On the one hand, I’ve been thirsty after a run in particularly hot weather and found this affected my performance. I’ve also felt the displeasure of needing the toilet during a running race. 

In the case of the latter, it can be a real challenge to stop and then restart after a toilet break. I found this to be particularly true half way through the London Marathon a few years ago!

This article will start by discussing hydration before, during and after different runs and then giving you six  of my essential tips on how to stay hydrated while running. I will then discuss other critical factors that you need to consider including symptoms of dehydration while running. So, for everything you need to know about staying hydrated on your early runs, keep reading.

How much water to drink before a run

While some of the information in this post speaks about staying hydrated throughout the day, it all contributes to you not feeling fatigued during your run.

Before a run, you should try to drink about 6 to 8 oz (170-220ml) of water. You shouldn’t drink the water just before you are going for your run. It is best if you drink the water about 30 minutes before your run.

This amount of water should give you a good basis of hydration for your run, but also not leave you feeling too full and needing the toilet while you are out. If you follow all of the tips that we list below, you should have a better chance of staying hydrated during a run. 

When it comes to the temperature, in my experience, it shouldn’t be too cold as this can shock the body. While it is minor, it is something to consider. 

How much water should I drink while running

It is important to drink fluids during longer runs to prevent injuries and loss of performance. It was found that runners often underestimate sweat losses and don’t drink enough to replace the lost fluids.

Runners should drink between 3 oz (85ml) and 10 oz (300ml) of fluid per mile to replace sweat lost. This figure will be individual and based on your weight and ambient temperature.

During research, runners were asked to run for 1 hour at their own pace to measure how much they lost through sweat and how much they drank. The research was designed to understand how much we underestimate our hydration needs during running.

Sweat Loss (ml)1,1151,7971,468
Total Fluid intake (ml)8031,137966

Hopefully this data highlight the importance of hydrating more than you expect during longer runs. It is important to drink fluids during longer runs to prevent injuries and loss of performance. Research in Medical & Science in Sports & Exercise recommends preventing body mass losses greater than 2% to prevent a decrease in performance. 

In my experience, some people like to break their run into distance segments, and some people like to break their runs down in terms of time. In my experience, using time is better than using distance when it comes to scheduling your water breaks.

Instead, it would be best if you took generous sips to quench your thirst and add a little bit of fluid to your body to help you keep going.

The Best Way to Rehydrate After a Run

We considered not putting this question in the article, but it does seem fitting. It is also a question that we get asked, but the answer is relatively straightforward.

Once you have completed your run and completed your after-run stretches, you want to drink water almost immediately and stay hydrated throughout the day. 

Runners Drinking

7 Essential Tips for Staying Hydrated for Runs

1. Stay Hydrated Throughout the Day

Staying hydrated throughout the day is something that may get overlooked by a lot of beginner runners. I realize that staying hydrated might sound obvious, but when we say “stay hydrated,” we don’t mean to drink many fizzy drinks; instead, you should drink around half a gallon of water every day.

Staying adequately hydrated throughout the day can improve your runs, and this is because your body will recover a lot faster from previous runs. Your body will also cope with the stress of your daily life a lot better. All of this adds to an improved morning run. 

I am not saying you should be a professional athlete, but they are an excellent example to use. See, it’s these little things like staying adequately hydrated throughout the day that sets athletes apart from non-athletes. There is no harm in incorporating small parts into your lifestyle, such as drinking the correct amount of water throughout the day.

But, let’s start with basic requirements for water and what those numbers are per day. The table below shows the Recommended daily intake of water for adults. 

European Food Standards AgencyNational Academy of Medicine
Females2.0 litres / day2.7 litres / day
Males2.5 litres / day3.7 litres / day

Remember that these numbers are not based on exercise and so should be the basis intake each day. You should plan to drink more if exercising as keeping hydrated will help you to run stronger and for longer.

2. Drink Water as Soon as You Wake up

It doesn’t even matter if you are going for a morning run or not; drinking water as soon as you wake up should be done every morning. Think about it, if you sleep for 8 hours, that is how long your body has gone without water. 

To add to the health benefits of drinking water early in the morning, you can squeeze a little bit of fresh lemon juice into the water. It is said that doing this helps people lose weight, but whether or not that is an old wives tale, we cannot say. However, lemon has a lot of beneficial properties, particularly vitamin C.

3. Go easy on coffee and caffeine Before and After Your Run

I love coffee, repeat LOVE coffee!

It is tempting to have a nice cup of coffee before your morning run, but you should never do this. Now, I will have to keep my personal opinion aside, but many people claim that it dehydrates you; however, there is no scientific evidence to back that up.

There are multiple studies that show caffeine can enhance athletic performance, which makes it popular amongst runners.

We know that coffee, or any caffeinated beverage, has a diuretic effect on our bodies, which may cause some of us to need to use the bathroom. There is nothing worse than needing to go to the bathroom while you are on your run. So, I suggest that you stay away from large coffees and instead have a nice espresso.

The American College of Sports Medicine recommends not drinking energy drinks before, during and after strenuous exercise, given their high caffeine levels. 

Here is some examples of the amount of caffeine found in some common products. 

DrinkApproximate Caffeine Content, mg
Coffee (8 oz)65-135
Espresso (2 oz)100
Tea (8 oz)50
Colas (12 oz)35-45
Diet Pepsi Max (12 oz)70
Red Bull (8.3oz)80
Caffine Tablets200

Source: ACSM: Health and Fitness Journal

How much caffeine can I drink before a run?

1-2 mg / kg of body weight can improve performance while there is a ceiling of 5 to 6 mg / kg body weight according to the ACSM

4. Do Not Over Indulge in Alcohol the Night Before

Much like with coffee, alcohol has a diuretic effect on our bodies. However, this effect is a lot more prominent when it comes to liquor, especially spirits. Alcohol thins our blood, but it also removes most of the fluid from it. Ever wonder why you use the bathroom so much when you drink alcohol? Well, it is for that specific reason.

If you consume some alcohol the night before you go for your run, make sure that you drink a lot of water at least an hour or two before your run. Make sure that you use the bathroom before you go for your run so you don’t need to go while on the run. You might be interested in our post on running with a hangover.

5. Use a Hydration Bladder

If you run long distances often, let’s say more than 10 miles a day, it won’t hurt to get yourself a hydration bladder. In fact, we have a recent article where we discussed this in detail. The hydration bladder is a small backpack that goes on your back with a bladder. The bladder can be filled with liquids, and it has a straw that you can use to take a sip when you get thirsty.

6. Replace Your Electrolytes throughout the Day

When you are drinking your water, it would be good to set some aside and add in some electrolyte supplements. An electrolyte is an electrically charged mineral. It is found throughout your body, specifically in your blood. 

I’ve always used Science in Sport products, I’ve found the lime flavour to be most agreeable. It really comes down to personal choice. Try various brands and flavours to see what works best for you.

Adding a little bit of electrolyte replacement to a bit of your water can quite literally help recharge your body. Remember, it is essential not to overdo it, though.

Is it best to run on an empty stomach in the morning?

I would not say that it is best to run on an empty stomach, but I will also not say that it is bad. If you are training for an event and running simply to get fit, having a light meal an hour before your run is highly beneficial to you.

If you do eat something before your morning run, I recommend that you keep it light. A small bowl of oatmeal with some fruits such as a banana will give you enough fuel to keep you going through your run and not make you feel too heavy.

Running on an empty stomach is called “fasted running.” Remember, if you have slept for 8 hours and ate 2 or 3 hours before going to bed, that means you haven’t eaten anything for 11 hours. That is technically a fast. 

When you run on an empty stomach, your body needs to find fuel from somewhere, so it often turns to stored fats. Your body will not reach a state of ketosis because that requires at least a few days of eating no carbohydrates, but it is as close as your body will come to achieving a state of ketosis.

How to stay hydrated on 10-mile Runs

To stay hydrated on a 10-mile run, the first thing you need to do is follow all of the steps outlined in this article. Before we get into a few extra tips, it is essential to remember that many people run ten or more miles without drinking water; however, if you are not fit enough to do that, I highly advise against doing it.

To stay properly hydrated on a 10-mile run, you need to take in a little bit of water at least every 30 minutes. Don’t try and stick to a per-mile drinking schedule because your 10-mile time is different from the person who might be telling you to drink water every specific amount of miles.

If you stick to a time-based schedule, you will be able to drink enough water to see you through the run, whereas if you are a slow runner, then taking a sip of water every five miles might be too long. 

Does Staying Hydrated Improve Running Performance?

Yes, staying hydrated most definitely helps improve your performance on your run. However, it is more important to think about the negatives of not staying hydrated. This will help you better understand why it is essential to remain not only hydrated but adequately hydrated on your runs. In the next section, we will talk about the symptoms of dehydration while running but for now, let’s talk about how dehydration affects your running.

Staying hydrated during a run helps maintain your performance, reduces the likelihood of cramps, muscle spasms, dry mouth, fatigue and loss of concentration. It will also help speed up your recovery.

If you have spent enough time running or doing any exercise, you eventually find out that your recovery is more important than the exercise itself. The same logic applies to running. So, while we can talk about the cramps and the spasms you get when dehydrated and trying to run, your recovery will be slowed down the most.

This means that on your next run, your performance will be significantly impacted negatively. Running while dehydrated can turn into a cycle. You will gradually become more tired on every run.

Symptoms of Dehydration While Running

Dehydration is no joke when you are running. It can cause you to feel as if you are ill, but it can also create problems within your muscles, such as cramps. Here is a list of the most common symptoms that you might incur while running dehydrated.

  • Cramps
  • Muscle spasms, primarily in your upper thigh.
  • Dry mouth
  • Fatigue
  • Tunnel vision
  • Loss of concentration

The most significant symptom of dehydration while running is fatigue. When you become tired from dehydration, it is different from just getting tired. It will feel like you have hit a wall because your body has run out of resources to keep it going. After all, water is essential to our life.

Cramps are not just an inconvenience, and while you can stretch them out, they can lead to more severe issues. When your legs cramp up, it becomes easier to pull a muscle, especially around the groin area. So, the minute you start cramping, slow down, stretch out the cramp and take it easy from there. Also, remember to stretch.

“Dry mouth” is highly uncomfortable. It can’t turn what was supposed to be a good run into an uncomfortable mess. Having a dry mouth can cause headaches.

Is It Better to Run in the Morning or Evening?

There is more than one factor to consider when it comes to the best time to run. What is best for one person might not be best for you. For example, if you have a hectic schedule early in the morning, running in the afternoon is best for you and vice versa. In general, though, we like to look at the best time to run for your core temperature.

The best time to run is in the late afternoon, according to studies. This is when your body is at its perfect core temperature. It is also a time when going for a run won’t shock the body because you’ve had an entire day to warm up.

Remember, if you do go for afternoon runs, you should follow one of our guidelines above and stay hydrated throughout the day. Doing this will help you optimize your performance on the road or trail.


Look, at the end of the day, there will come a time where you can’t just go for a run; come back and carry on with your day. You are going to start getting more and more tired as you get older. Stretching before and after your run can prevent any injuries and can help with recovery but staying hydrated while running is essential to not only your performance but to your health as well.

Mark Norman


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