You don’t need 8 glasses of water.

This is a public service announcement. You don’t need a set amount of water each day to be healthy. Associate Professor Michael Farrel and PhD student Pascal Saker of Monash University have performed a study that shows that excessive water drinking actually hurts you.
The study was conducted in two parts. The first part of the study was to determine the effort it took to swallow water when thirsty after exercise. Not surprisingly, the participants reported that there was no effort required in swallowing water when thirsty. The second part of the study was to determine the effort it took to swallow additional water after already drinking a large amount water. The results this time were that it took about three times more effort to swallow the extra amount of water.
The body’s natural resistance to swallowing water when the person is fully hydrated indicates that the ability to swallow gets impaired after drinking water excessively. Using an fMRI, Farrel and Saker watched for brain activity specifically before swallowing the water. The study showed that the frontal cortex of the brain activated the swallowing inhibition. The scientists concluded that the swallowing inhibition is how the brain balances how much water is in the body. If the body has too much water already, it is harder to swallow additional water.
This overdrinking will not just impact your swallowing, or your bathroom habits. Drinking too much puts the body in danger of intoxication, or hyponatremia. Hyponatremia occurs when the sodium level in your blood is dangerously low. The symptoms range from lack of energy and nausea to convulsions and coma. And this knowledge isn’t new. In September 2008, a 47 year old British hiker died due to hyponatremia. Her husband said she drank a large amount of water and ate almost nothing before hiking the 6.2 miles across the Grand Canyon.
I’m sure she drank so much water before hiking because she was following advice and trying to avoid dehydration. In fact, any athlete can recite the coach’s pre-contest mantra: “Hydrate, hydrate, hydrate!” This study proves that just drinking eight glasses, or pushing large amounts of water to hydrate, without paying attention to your body signals, can actually be harmful. While you should always be careful to stay hydrated in daily life and during exercise, you should also listen to your body. If it seems difficult to swallow the water you are drinking, stop. You are fully hydrated or your sodium levels are low. Instead, Farrel and Saker suggest that you just drink when you’re thirsty, not on a schedule.

Monash University. “Do you really need eight glasses a day? Study challenges idea of mandatory water intake.” ScienceDaily. ScienceDaily, 7 October 2016. <>.

2 thoughts on “You don’t need 8 glasses of water.

  1. Matthew Hogan

    I heard this a lot growing up from my parents and I wondered if this was true because I felt like sometimes this could be a lot of water to drink in a day depending on what you are doing. This study definitely makes a lot more sense because there are times where your body doesn’t need a lot of water and times when it does, such as when you are doing physical activity. I was a little bit surprised to see that drinking too much water can be harmful to you, but I guess too much of anything is bad, even water.

  2. Lauren Hile

    Your blog post makes an interesting point. I always try to stay as hydrated as I can because I can easily get headaches, and staying hydrated throughout the day almost always keeps them away. That being said, though, I do not drink 8 glasses a day. I’ve also always been a little skeptical of this because I’m 5’2 , so I’ve always wondered how me drinking 8 glasses of water would be as beneficial as someone who is taller and weighs more drink the same amount. The water company, CammelBak, actually has a hydration calculator where you can put in your height, weight and amount of physical activity you do, among other things, and they calculate how much water you need. ( When I calculated mine it turned out that I needed only 6 or 7 liters of water/day on days that I run for 30 minutes. I feel like this calculator is more accurate than everyone drinking 8 glasses of water everyday.

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