Are you drinking enough?

Recent changes to how we work, have meant that there are a lot less conversations at the water cooler! However, while we may not be having as many chance conversations at the water station are you drinking enough when you are at work?  Water is essential for life. In fact, we could survive much longer without food than water! The human body is made up of between 45% and 75% water by weight. This is equivalent to 42l (litres) for a 70kg
male and 26l for a 50kg female depending on their body composition (1). 75% of our brain mass is water, so when we combine this with the many complex interactions in our body where water is essential, it’s clear to see why we need to ensure that we stay well hydrated.

As adults between 45% and 75% of our body weight is water!

Research is now showing that being adequately hydrated is important, as it plays an important role in regulating our mood, productivity and concentration (2).

Why is our water intake important?

Water is an essential component of the many chemical reactions that occur within our body. It’s also vital for many other less well-known functions like; forming saliva to allow us to swallow, to fluid within our joints, lubrication for our eyes, waste excretion, body temperature regulation and in the blood system it is essential for carrying glucose, oxygen and nutrients to the cells. Our body uses a lot of water each day. Therefore we need to ensure that we are drinking enough to replace what is lost, allowing our body to function as needed. It’s also important to note that water levels in our body change as we age. New-borns have a higher body fluid level compared to adults. While elderly adults tend to have lower fluid levels (3).

Even 2% dehydration impairs our performance in tasks that require attention, psychomotor and immediate memory skills!

When we fail to intake enough water, we can suffer dehydration. Dehydration is defined as 1% or greater loss of body mass due to fluid loss.

Even mild dehydration of 2% (loss of body mass) can lead to (1):

  • Impaired cognitive function
  • Reduced physical performance
  • Headaches
  • Symptoms of fatigue

Overhydration or hyponatraemia while rare, is also associated with health risks.

Does it matter where we get our hydration it from?

We obtain approx. 20% of our water requirements from food, as many fruit and vegetables are up to 90% water. The rest tends to come from drinks including; tea, coffee, milk, sugary drinks, juices and alcohol. While all provide water, some provide more additional nutrients that are beneficial for health. Others contain additional energy, caffeine, sugar or sweeteners that we may not need. In Ireland, the 2021 Healthy Ireland Survey showed that; 8% of adults report drinking sugar-sweetened drinks every day and that 6% report drinking diet, low-sugar or no added sugar drinks every day. 57% reported that they consumed alcohol at least once a week, with 33% drinking on multiple days each week (4).

Though teas, coffees and sugary drinks do count towards our daily intake and a moderate intake of coffee (3-4cups) can enhance concentration, too much can cause anxiety and raise blood pressure (5). So, water on its own, is the best way to hydrate!

How much do we need and are you drinking enough?

If our body is short on fluids, one of the first signs is a feeling of fatigue. Even mild dehydration as mentioned, of 1% to 2% can impair physical and mental performance (1,5). How do we know if we are drinking enough? Two easy indicators are thirst and urine colour. The lighter the colour of urine the more hydrated we are and the darker the more dehydrated we are. As adults, we are recommended to drink between 8 -10 cups (200ml capacity) or between 1.5 and 2lts daily (3). However, keep in mind that you may need to adjust it for example if the weather is very warm or if you exercise. This will vary depending on the intensity, time, and conditions of the exercise, you may sweat
more and need to replenish this loss.

Some tips to help increase your water include:

  • Keep a large glass or litre bottle of water at your desk or in the car, as a gentle reminder to drink.
  • Set a reminder alarm on your phone!
  • Add flavour with berries, citrus fruits, cucumber or herbs like mint to help you drink

In conclusion, water is essential for us to function properly and our bodies are finely tuned to control the water levels in our bodies. However, it’s important that we are aware of the signs when we need to drink more and listen to them. Drinking water is best, it can be the easiest to do and will ensure that we are less likely to suffer any of the negative impacts of reduced physical and mental performance.


  1. Benelam, B. and Wyness, L. (2010a) ‘Hydration and health: A Review’, Nutrition Bulletin, 35(1), pp. 3–25. doi:10.1111/j.1467-3010.2009.01795.x.
  2. Adan, A. (2012) ‘Cognitive performance and dehydration’, Journal of the American College of Nutrition, 31(2), pp. 71–78. doi:10.1080/07315724.2012.10720011.
  3. BDA, The importance of Hydration, British Dietetic Association (BDA). Available at: (Accessed: 01 June 2023).
  4. Healthy Ireland Survey 2021Summary Report, Available at: (Accessed: 01 June 2023).
  5. Benton, D. (2011) “Dehydration influences mood and cognition: A plausible hypothesis?” Nutrients, 3(5), pp. 555–573.