Focus on Fatigue

Focus on Fatigue, Issue 49: Water – How much is enough?

By September 10, 2017 No Comments

Welcome to Focus on Fatigue,

There’s nothing better in the height of summer than a tall glass of cold water. During the winter months, however, we may reduce our water intake or find ourselves turning to drinks other than plain water (such as hot tea) to slake our thirst. The importance of staying hydrated is well-known, but how do we know when we’ve drunk enough? And do the type of liquids we consume make a difference? This month in Focus on Fatigue we will look at ways to stay hydrated year round, no matter what we’re drinking.

The FRMS Team



InterDynamics Pty Ltd
320 Adelaide Street Brisbane Qld 4000
Tel +61 2 8404 0400 Ext 23

Views expressed in articles and links provided are those of the individual authors, and do not necessarily represent the views of InterDynamics (except where directly attributed).

Featured Article

Water: How Much is Enough?

Water makes up a large portion of the human body, ranging from 75% when we are born, to around 55% as we age. It is essential for many bodily functions, including digestion, absorption of nutrients, and thermoregulation. Every day we lose water through natural processes such as perspiration, breathing and the elimination of waste. Therefore, we must continually replace this water through eating and drinking. Failure to replace this water would result in death within a few days. But how much water do we need to consume to ensure our bodies maintain optimum hydration levels?

How much water do we need?

The Australian Government has suggested that adult men should consume 3.4 litres of water each day (including 2.6L of fluid) and adult women should consume 2.8 litres per day (including 2.1L of fluid). This recommendation was based on the median intake from a National Nutrition Survey. Does this mean that if you aren’t drinking litres of water each day, that you’re at risk of dehydration? Not necessarily.

There is no proven level of water intake that would ensure adequate hydration for all people. Therefore, individuals should consider several other factors when looking at their water intake. This includes personal factors such as size and the amount of physical exercise you do, as well as environmental factors like heat.

It’s important to remember that we get about 20% to 25% of our daily water intake from the food we eat. Also, the fluid portion of our water intake does not come just from plain water alone. For example, we are consuming water when we put milk on our breakfast cereal, when we have a cup of coffee, or when we drink a soft drink.

When drinking fluids other than plain water, however, it is important to consider what is being consumed with the water. For example, milk provides the body with calcium and other essential nutrients, while soft drink is largely made up of sugar which may lead to a high caloric intake and other health problems. The amount of caffeine contained in beverages should also be considered, to prevent the consumption of unsafe levels.

What are the effects of mild dehydration?

Many researchers have studied the effects of mild dehydration on the human body. This often involves achieving a body mass loss of one or more percent through exercise and/or diuretics. Such research has found that mild to moderate dehydration can negatively affect short-term memory, mood, concentration, alertness, perceptual discrimination, arithmetic ability, visuomotor tracking, psychomotor skills, perception of task difficulty, and balance.

Is it possible to drink too much water?

Consuming excessive amounts of water can cause a condition known as hyponatremia, in which sodium levels in the blood drop too low due to dilution. Symptoms include nausea, poor balance and even organ failure. However, unless you’re an endurance athlete, hyponatremia is not really something you need to be concerned about.

The golden rule

The human body has an excellent method of preventing dehydration: thirst. Therefore, the best way to ensure adequate hydration is to listen to what your body is telling you, and never force yourself to drink more to achieve a pre-determined level. Drink when you are thirsty. Drink more water than any other beverage. Your body will thank you for it.


  • Armstrong, L. E., Ganio, M. S., Casa, D. J., Lee, E. C., McDermott, B. P., Klau, J. F., Jimenez, L., Le Bellego, L, and Chevillotte, E. (2011) Mild Dehydration Affects Mood in Healthy Young Women. The Journal of Nutrition, 10(3945).
  • Ganio, M. S., Armstrong, L. E., Casa, D. J., McDermott, B. P. (2011) Mild dehydration impairs cognitive performance and mood of men. British Journal of Nutrition, 106(10), 1535-1543.
  • Lieberman, H. R. (2007) Hydration and Cognition: A Critical Review and Recommendations for Future Research. Journal of the American College of Nutrition, 26(5), 555S-561S.
  • McKinney, J. L., Eberman, L. E., Cleary, M. A., Lopez, R. (2005) Effects of dehydration on balance as measured by the balance error scoring system. Southeast Athletic Trainers’ 30th Annual Member’s Meeting and Clinical Symposium, Atlanta, GA. March 2005.
  • Nutrient Reference Values for Australia and New Zealand: Water (2005) Australian Government: National Health and Medical Research Council.
  • Popkin, B. M., D’Anci, K. E. and Rosenberg, I. H. (2010) Water, hydration and health. Nutrition Reviews, 68(8), 439-458.
  • Smith, M. F., Newell, A. J., and Baker, M. R. (2012) Effect of Acute Mild Dehydration on Cognitive-Motor Performance in Golf. Journal of Strength and Conditioning Research, 26(11), 3075-3080.

InterDynamics News

Conferences and presentations

ISPO Conference (21-22 June 2017)

Rotterdam, The Netherlands

The ISPO (International Standard for Maritime Pilot Organizations) is a standard of best practice for pilots and pilot organizations, improving safety and quality. Providing self-regulation and transparency in pilotage standards to all port related stakeholders. This year, the annual ISPO conference was held in Rotterdam.

InterDynamics’ staff gave a presentation on ‘Implementing a Fatigue Risk Management System’ at the conference.

In the News

Provided below are a selection of articles from around the web on the issues associated with fatigue. We hope you find them useful and interesting.

Video: How much water do we really need to drink?

Seeker, 4 December 2013

Does the saying that you need eight glasses of water a day actually hold water? Trace looks at how much H2O you really need to drink to keep your body in prime shape.

Article: Brain’s biological clock stimulates thirst before sleep

Science Daily, 28 September 2016

The brain’s biological clock stimulates thirst in the hours before sleep, according to a study. Scientists have known that rodents show a surge in water intake during the last two hours before sleep. The study now reveals that this behavior is not motivated by any physiological reason, such as dehydration. So if they don’t need to drink water, why do they?

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