Why is Water Essential for Life (and possibly Beyond)?
When scientists search the skies for signs of life, there’s one phrase that keeps coming up: “follow the water“. That’s because liquid water is considered so essential to life as we know it that it’s the first thing researchers look for when scanning other planets.
What Makes Water So Special?
It all comes down to water’s unique chemical properties. A water molecule (H₂O) is made up of two small, positively charged hydrogen atoms and one larger, negatively charged oxygen atom. This gives water molecules polarity – meaning one end of the molecule is slightly positive and the other slightly negative.
This polarity is what allows water molecules to:
- stick to each other (cohesion),
- stick to other substances (adhesion), and
- dissolve more substances than any other liquid (earning it the nickname “the universal solvent”)
These abilities are why water is the ideal environment for the thousands of chemical reactions happening constantly inside every living cell. It helps break things apart, dissolve nutrients, transport them where they’re needed, and keep cellular machinery humming.
Water Holds Life Together – Literally
Polarity also helps explain how cell membranes form. In water, special fats (called phospholipids) arrange themselves in a neat double-layer structure, with water-attracting ends facing outward and water-repelling ends facing inward – just like the skin of a soap bubble. These membranes are what allow individual cells to exist, by keeping the complexity of life inside separate from the “chaos” outside.
Thanks to water, we have cells. And thanks to cells, we have… well, life!
Water's Role in Plants, Animals – and You
The same “stickiness” properties of water that helps form cell membranes also makes it possible for plants to draw water up through their roots. Cohesion and adhesion allow water to travel through narrow tubes (xylem) that pull water up from the soil to the tops of tall trees, even against gravity. This process is also at work in animals and in your own body, where water moves through blood vessels and tiny capillaries to carry nutrients and oxygen, and remove waste. In addition, water helps maintain the shape and structure of cells and tissues by providing turgor pressure. In plants and soft-bodied animals, this pressure is essential for maintaining their shape and rigidity.
Oh, and let’s not forget photosynthesis – the process plants use to create food from sunlight. It wouldn’t happen without water. In other words: no water, no food chain.
Water and Human Health
Water isn’t just essential for life – it’s essential for living well. Every single system in your body relies on it. Without enough water, things start to go wrong… quickly.
Here’s what water does for your body:
- Regulates temperature – Water can absorb a large amount of heat without significant temperature changes. This property helps regulate body temperature, preventing extreme fluctuations that could be harmful. Water also requires a large amount of energy to evaporate. This allows your body to cool down through sweating (transpiration), helping to maintain a stable internal temperature.
- Transports nutrients and oxygen – Water is the main ingredient in blood and other bodily fluids, which carries vital nutrients and oxygen to cells throughout your body.
- Flushes out waste – Water helps remove metabolic waste products through urine, sweat, and bowel movements.
- Supports digestion – As a solvent and medium for chemical reactions, water is a key player in breaking down food and moving it through the digestive system. It also helps prevent constipation.
- Keeps cells healthy – Water is crucial for maintaining cell structure and function, enabling biochemical reactions, and keeping tissues hydrated.
- Provides structural support – Through turgor pressure, water helps support the shape of soft tissues, muscles, and organs.
- Protects joints and organs – Water lubricates joints and cushions organs.
- Boosts brain and mood – Good hydration is linked to better focus, sleep, mood, and memory.
How Much Water Do You Really Need?
In New Zealand (and many other places), the general guideline is:
- Women: Around 2 litres (about 8 cups) per day
- Men: Around 2.5 litres (about 10 cups) per day
You may need more if you’re very active, live in a hot climate, or are pregnant or breastfeeding. And as we get older, our sense of thirst can dull, so it’s important to drink regularly – even if we don’t feel thirsty. A good hydration marker is urine colour – pale yellow is ideal, dark yellow or amber suggests dehydration, and consistently clear urine may indicate overhydration or water intoxication.
Dehydration can lead to serious issues, especially for babies, young children, older adults, and people with health conditions. Symptoms include dizziness, fatigue, dry mouth, and confusion – and if it gets severe, it can become life-threatening.
Overhydration dilutes your blood and decreases the electrolytes in your body, especially sodium. As a result, water moves into your body’s cells and causes them to swell. Too much water in your brain cells increases pressure on your brain and affects how it works. This leads to changes in your awareness, movement and behaviour. Water intoxication is potentially fatal.
Electrolytes: Water’s Wingmen
Electrolytes are minerals (like sodium, potassium, calcium, magnesium, chloride and phosphate) that carry an electrical charge when dissolved in water. They’re found in your blood, tissues, and cells, and they help your body do some pretty important things.
Why Are They Important?
- Fluid balance – Fluid balance in the body refers to maintaining a stable internal environment by regulating the input and output of fluids. Optimal fluid balance is crucial for various bodily functions, including cellular metabolism, temperature regulation, and the delivery of oxygen and nutrients. This involves keeping the amount of water and electrolytes, like sodium and potassium, within healthy ranges.
- Turgor pressure – Electrolytes play a crucial role in regulating hydrostatic pressure within cells, which is essential for cell structure and function.
- Muscle and nerve function – Electrolytes enable nerves to send signals and muscles to contract – vital for everything from blinking to steady heart rate and rhythm.
- pH regulation – Electrolytes are crucial for maintaining the body’s acid-base balance, so your cells can function properly.
- Nutrient and waste transport – Electrolytes help move nutrients into cells and waste products out.
Where Do You Get Them?
You don’t need “electrolyte-enhanced” sports drinks to get your electrolytes. They’re in all whole foods like:
- Meat, seafood and eggs
- Fruits and vegetables
- Dairy, nuts, and seeds
- Whole grains
- Mineral water
Sports drinks can be helpful if you’re doing intense physical activity for extended periods (like endurance running or working in extreme heat). But for most people, plain or mineral water – and a balanced diet – do the trick just fine.
In fact, many sports drinks contain added sugar and are high in calories, which can outweigh the benefits if you’re not burning through them with heavy exercise. Some also contain other dodgy ingredients, such as artificial sweeteners and colourants, which can be detrimental to your health. Sports drinks are not recommended for everyday hydration, especially for kids.
In Summary
Water isn’t just important – it’s foundational. It’s the medium that makes life possible, from the tiniest cell to the tallest tree. It cools us, cleans us, carries nutrients, and cushions our organs. It helps regulate everything from blood pressure to brain chemistry.
Electrolytes, meanwhile, are like water’s backstage crew – quietly keeping things balanced and running smoothly.
So drink up, eat a varied diet, and take good care of your hydration. Your body (and brain) will thank you for it…