I've run a number of races, and there are almost always a number of water stations. I don't usually stop for water on the short races, but I'm not sure how long of a race I should do that for - when should I start drinking water? How much and often should I drink it?


4 Answers 4


Hydration when racing has a lot of variables, all of which need to be taken into consideration for longer races - which I would say is anything longer than a 10k:

  • difficulty of the course (hills, headwind, altitude)
  • temperature and humidity
  • and your acclimatization to those weather conditions
  • your effort, this is somewhat of a double edged sword: run fast and you're done quicker, run slow and you're out there longer, and often you'll be out in the warmer parts of the day more than the early finishers.
  • your body: everyone sweats different amounts. Some don't drink much during a 1/2 marathon, some drink a liter or more.
  • for longer races, your nutrition intake also adds a fluid component: you need water for your body to digest the nutrition.
  • pre-race hydration: it's not uncommon for racers of >4 hour races to adjust up their electrolyte and hydration in the days leading up to a race.

First - try to do a sweat test in an environment as close as you can to the race, and get a good idea of what you generally need, and then consider the other variables.

At the end of a race you will almost never hear people saying "oh dang, I drank too much", but go by the medical tent after a marathon, and you will see racks of people wishing they had taken hydration more seriously.

  • 2
    You can drink to much. See hyponatremia. This form of hyponatremia, or low sodium, is caused when overhydration while exercising dilutes the sodium level in your body. Possible result, in the most serious cases: Brain swelling that could lead to seizures and other life-threatening complications. This makes hyponatremia arguably the most important marathon-related health risk facing you and your buddies. Feb 12, 2012 at 22:14
  • There's plenty of recent research suggesting that you can drink too much, and yeah, you will hear people saying, "oh dang, I drank too much," unless, as @solomongaby points out, they've been sent to the medical tent with hyponatremia.
    – pjmorse
    Sep 25, 2013 at 15:06
  • 1
    Cerainly hyponatremia is a big concern, thus my suggestion to not just wing it, but to do a sweat test. I think I would turn it around - the problem with hyponatremia in athletic events is not drinking too much water, it's drinking too much water in relation to the amount of electrolytes ingested. That being said, there are two things in play here...I think the number of people who drink too little overwhelmingly dwarfs the number who over-drink in long races. But point well taken, over drinking without minding your electrolytes can lead to a life threatening situation. Sep 25, 2013 at 19:13

It depends on the race and the weather. At a marathon i stop at almost every station and grab a glass of water and have sip. Its better to hydrate in small sips from time to time.

With a bit of practice you can even learn how to drink while running so you don't lose to much time at the stations.


Ideally, you'd have a little straw follow you around and you could have a constant drip of hydration. Take a cup at every water station, and take a few sips. Depending on how far apart they are, you'll want to drink more or less, aiming for an ounce of water every 4 minutes since your last station. This isn't an exact calculation, but it's a good place to start from.

This is going to leave you with leftover water almost every time. I personally would use the remaining water to cool off and keep yourself alert with a good face splash. Unless it's gatorade, then it probably wouldn't feel so good on your face :)


It's really much simpler than this. The marathon doctors have been recommending the following for a few years now, with the risk of hyponatremia in mind:

If you're thirsty, drink.


Additionally, this 2001 statement from the International Marathon Medical Directors Association (IMMDA), which concludes:

"Accordingly perhaps the wisest advice that can be provided to athletes in marathon races is that they should drink ad libitum and aim for ingestion rates that never exceed about 800 ml per hour."

  • I know some people (runners and casual alike) that sometimes dehydrate because their bodies do not "tell" them when they are thirsty. Therefore, for some of us, it's not that simple. Who are these "marathon doctors" you speak of?
    – user527
    Nov 21, 2012 at 14:20

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