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Water – why do we need it?

Why do we need water and how this this vary between people? Where does water fit into homeostasis? Find out in this article.
girl drinking from water bottle

We need enough water in our body for physiological function and health. We cannot live for more than about 100 hours (about 4 days) without water.

Have a look at what water helps our body with. Water…

  • Hydrates: It moistens tissues in mouth, nose and eyes
  • Helps swallowing: It moistens food, making it easier to swallow
  • Helps kidney function: Adequate hydration maintains optimal kidney function. This is often popularised as water helping to flush out toxins
  • Provides solvent: It provides a solvent for ions and organic molecules to dissolve into
  • Protects: It helps provide protection for organs
  • Lubricates: It lubricates joints
  • Regulates temperature: It regulates body temperature

Body water content varies between individuals and through life, depending on gender and age. Some differences are:

  • Infants and young children need more water in proportion to their body weight as they cannot concentrate their urine as efficiently as adults
  • Infants also have a greater surface area relative to weight, so water losses from the skin are greater
  • Men need more water than women due to their higher (on average) fat-free mass and energy expenditure

pregnant woman, female sports, older man

Homeostasis requires that water intake and output be balanced.

Let’s look at how we take in water and how we lose water next.

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Finding the Body’s Balance: Understanding Homeostasis

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