Eight glasses too many? Hydration myth busted!


Do you have a fashionable or favourite water bottle that you fill-up each day before you leave the house? Are you committed to drinking eight, eight-ounce glasses of water a day?

Science says you may not have to.

But before you toss your bottles in the recycling bin, we’re busting this hydration myth and reinforcing the benefits of getting your daily dose of H20.


Myth: You need to consume eight, eight-ounce glasses or two litres of water a day.


According to an editorial in the Australian and New Zealand Journal of Public Health, the recommendation of eight glasses or two litres a day was driven by ‘vested interests’ rather than a need for better health.

Surprisingly, unlike many nutrients, there is no set minimum level of water intake.

In a recent article in the British Medical Journal, family physician Dr. Margaret McCartney examines the notion that needing eight glasses of water a day for health has been encouraged without any scientific evidence to support it.

Dr. McCartney says that humans have a thirst mechanism that’s efficient and should guide us in our water consumption. “There’s no good evidence for how much we need to drink on average a day. It depends on how active we are, how much water is in the food we’ve eaten, how hot it is and if we have any medical conditions,” said Dr. McCartney in an another article.

There are a number of benefits believed to be connected to drinking water such as improving skin tone, reducing urinary tract infections, reducing headaches, and eliminating constipation. But according to Dr. McCartney there isn’t any substantial evidence to support any of this.

What happens if you drink the recommended two litres of water a day?


According to the Australian editorial, this depends on how you drink this water. For instance, if you were to drink the two litres within a short time, this will likely mean the water you drink will not reach the space where it is needed, and as such has “no real effect on hydration; all it does is dilute the urine.”

In fact, evidence suggests the over-consumption of water, particularly in children, could be detrimental.

What you need to know


Recommended numbers for water intake are simply guidelines for entire water consumption, meaning all beverages and water-containing foods count toward your daily allowance. Fruits and vegetables offer an alternative to direct water consumption. Consider watermelon, grapefruit, cucumbers, celery, tomatoes, and lettuce and even baked potato which is 75 per cent water.

For optimal health, hydration and energy, you should be consuming water-containing foods and drink water throughout the day.  If you’re thirsty or in doubt, you should drink a little more water, rather than a little less – but doesn’t mean you need to attain an eight glass target every single day.

Quenching your thirst


Dr. Stanley Goldfarb, a nephrologist at the University of Pennsylvania, reviewed the research claims and studied how the kidneys handle it. He said in an article that there isn’t any evidence that a person needs to drink more water than what their thirst dictates.

It’s important to remember that the fewer fruits and vegetables you are consuming, the more dried and/or processed foods you tend to turn to. This means you’ll likely need to consume more water to compensate.

In the same article, Dr. David Price, head of family medicine at McMaster University said a good guide to tell if the body’s fluid levels are in balance is to check the colour of your urine. “If it’s very dark, you’re on the dry side; if it’s very light or translucent, then you need to drink a bit less water.”

Are you committed to drinking eight glasses a day? Will you now rely on thirst instead?


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Submitted By: Jen Anderson

“…over-consumption of water, particularly in children, could be detrimental.” Can someone elaborate on this? That’s a very general statement, and doesn’t tell us anything! What exactly is wrong with having clear urine?

Submitted By: Doctors Nova Scotia

Hi Jen, thanks for your comment.

The overconsumption of water can be harmful to a person’s health. Overconsumption, or water intoxication, is a condition caused by drinking too much water resulting in the balance of electrolytes in the body to exceed normal limits.

The water we consume is removed primarily through the urine and sweat. The amount of water in the body is regulated to manage the levels of salt in the blood.

If you drink too much water, eventually the kidneys will not be able to work fast enough to remove sufficient amounts from the body, so the blood becomes more dilute with low salt concentrations.

Hyponatremia, is an electrolyte disturbance in which there is insufficient salt in the blood. Severe cases of hyponatremia can lead to water intoxication, an illness whose symptoms can include headache, fatigue, nausea, vomiting, frequent urination and mental disorientation.

Accidentally drinking too much water resulting in water intoxication is rare, but it does happen. This tends to happen most in elderly people whose kidney function may be impaired, people who drink several litres of water in a short amount of time, and marathon runners.

Using urine colour to determine hydration levels can be tricky because there are many reasons why your urine may or may not be clear. Some medicines such as antibiotics, laxatives, and chemotherapeutic drugs can darken your urine.

Carrots, beets, and other foods can also affect the colour of your urine. High amounts of vitamin C in foods, or pill form, can also darken the colour your urine.

For optimal health, hydration and energy, people should consume water-containing foods and drink water throughout the course of the day. Thirst is a great indicator of how much water you should consume.

Submitted By: Colin Drake

Over the past decade, I’ve built up a habit of drinking a ton of water. I’m talking around 3-6 litres a day, depending on the season/activity level/etc. I find a drink a lot during the work week at my desk. Even if I’m not as dehydrated as I should be to consume those levels at times, would it be detrimental to my health to consume that much on a regular day? My urine is no doubt clear as water majority of the time unless I’ve logged a 5 mile run the day of or before.