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Functions of Water

By Julie Mansfield | 4th Mar, 2017

Functions of Water

Water is, without question, the most important of all nutrients, because without it, humans can only survive a number of days.

Water makes up two-thirds of the human body weight (approximately 37 litres) and is essential for every bodily function.

  1. Increases Energy & Relieves Fatigue – Your brain is 75% water, drinking it helps you think, focus and concentrate better and be more alert. As an added bonus, your energy levels are also boosted!
  2. Regulates Temperature – Water plays a vital role in regulating temperature
  3. Protection – Water protects the body’s joint, organs and other tissues
  4. Promotes Weight Loss – Water suppresses the appetite and helps to combat over-eating!
  5. Flushes Out Toxins – Gets rid of waste through sweat and urination which reduces the risk of kidney stones and Urinary Tract Infections.
  6. Maintains Regularity – Aids in digestion as water is essential to digest your food and prevents constipation.
  7. Natural Headache Remedy – Helps relieve and prevent headaches (migraines & back pains too!) which are commonly caused by dehydration.


Human Brains are 75% water

Human Bones are 25% water

Human Blood is 83% water.

Mild Dehydration 1% loss of body water: –

  • Sluggishness
  • General Fatigue & Tiredness
  • Headaches
  • Dark brown coloured urine

Moderate Dehydration 3% loss of body water: –

  • Decreased blood plasma
  • Decreased kidney function
  • Decreased blood flow to skeletal muscles
  • Light headiness/Headaches
  • Increased risk of constipation
  • Reduced metabolic rate

Severe Dehydration 5% loss of body water: –

  • Heat exhaustion – which can lead to medical attention

Vey Severe Dehydration >10% loss of body water: –

  • Will lead to heat stroke and if sustained for any great length of time, can result in death. 


Fluid Intake Guidelines

To avoid dehydration, it is recommended that we consume 2.0 to 2.5 litres a day OR 1 litre of fluid for every 1,000 calories consumed.

Post exercise = 0.5 litres of water.

Fluids NOT to Drink

Diuretics like caffeine-containing drinks like coffee, carbonated drinks & alcohol will dehydrate you. 

Urine Test

To check hydration levels….


Urine Colour Hydration Level
Clear Hyper hydrated
Very pale yellow Hydrated
Pale Yellow Hydrated
Yellow Mild dehydration
Dark Yellow Dehydration
Orange or Brown Extremely dehydrated.