Understanding Water: Which one of the following is false about water?

December 14, 2025 •

4 min read

Approximately 71% of the Earth's surface is covered by water, yet many misconceptions persist about its fundamental nature. From its chemical structure to its physical properties, water is a surprisingly complex substance that defies common assumptions. This article will debunk some of the most common falsehoods and clarify the science behind our most vital resource.

Quick Summary

This article explores common myths and scientific facts about water. It explains the molecular polarity and hydrogen bonds responsible for water's unique behaviors, including its high heat capacity, vaporization, and density anomaly. By clarifying misconceptions, it provides a clearer understanding of water's true properties.

Key Points

Water is polar: The oxygen atom pulls electrons, giving it a partial negative charge and creating a bent, polar molecule.
Hydrogen bonds explain unique properties: Water's polarity enables strong intermolecular hydrogen bonds, leading to its high heat capacity and boiling point.
Ice is less dense than water: The crystalline structure of ice is more spread out than liquid water, causing ice to float and insulate aquatic environments.
Boiling doesn't remove all contaminants: While boiling kills pathogens, chemical pollutants and heavy metals remain.
Hydration needs are variable: The 'eight glasses of water' rule is a myth, as individual hydration requirements differ.

Debunking the Top Falsehood About Water

One of the most persistent and significant falsehoods about water, often found in science quizzes, is the statement that water is a nonpolar molecule. This is fundamentally incorrect and misunderstands the very nature of the H₂O molecule. Water is, in fact, a polar molecule, and this single characteristic is responsible for many of its unique and life-sustaining properties.

The Polarity of the Water Molecule

A water molecule consists of one oxygen atom bonded to two hydrogen atoms. The oxygen atom is highly electronegative, meaning it pulls the shared electrons closer to itself, away from the hydrogen atoms. This creates a partial negative charge near the oxygen atom and partial positive charges near the hydrogen atoms. This uneven distribution of charge makes the molecule polar, giving it a bent shape, unlike the linear structure of a nonpolar molecule like carbon dioxide. This polarity enables water molecules to form hydrogen bonds with other water molecules, which is the key to all its special characteristics.

The Consequences of Hydrogen Bonding

The presence of strong intermolecular hydrogen bonds, which are attractions between the partially positive hydrogen of one water molecule and the partially negative oxygen of another, has profound effects on water's properties. These bonds are weaker than covalent bonds but strong enough to give water a high boiling point and high heat capacity. For water to change state, these bonds must be broken, which requires a significant amount of energy.

High Specific Heat Capacity: Water can absorb a large amount of heat energy before its temperature increases. This is crucial for regulating the Earth's climate and for biological systems, as it helps organisms maintain a stable internal temperature.
High Heat of Vaporization: A large amount of energy is needed to turn liquid water into gas. This property is exploited by many animals, including humans, for cooling through evaporation.
Cohesion and Adhesion: Water's polarity and hydrogen bonding cause it to be attracted to itself (cohesion) and to other substances (adhesion). These properties allow for capillary action, which is essential for transporting water in plants.

Water's Density Anomaly: The Floating Ice

Another property of water that can lead to false assumptions is its density. Most liquids become denser as they freeze. However, ice is less dense than liquid water, which is why it floats. As water freezes, the hydrogen bonds force the molecules into a rigid, crystalline lattice structure that is more open and spread out than the random arrangement in liquid water. If ice sank, lakes and oceans would freeze from the bottom up, killing aquatic life. Instead, the floating ice provides an insulating layer, protecting the life below.

Dispelling Other Common Water Myths

Beyond the fundamental chemical properties, other practical misconceptions about water are widespread:

Myth: Boiling water removes all contaminants. Fact: Boiling effectively kills harmful bacteria and pathogens, but it does not remove heavy metals, chemicals, or other mineral contaminants.
Myth: All tap water is of poor quality. Fact: In many developed countries, tap water is highly regulated and tested, making it safe and often comparable in quality to bottled water.
Myth: You must drink exactly eight glasses of water a day. Fact: This is a common rule of thumb, but individual hydration needs vary based on factors like activity level, climate, and overall health.

The Truth vs. The Falsehoods: A Comparison


Feature	Common Falsehood	Scientific Fact
Molecular Polarity	Water is a nonpolar molecule.	Water is a polar molecule due to its bent shape and uneven charge distribution.
Boiling Point	Water has a low boiling point.	Water has an unusually high boiling point due to strong hydrogen bonds.
Ice Density	Ice is denser than liquid water.	Ice is less dense than liquid water, allowing it to float and insulate aquatic life.
Purity	Boiling water purifies it completely.	Boiling kills biological contaminants but leaves behind chemicals and heavy metals.
Hydration Rules	You must drink 8 glasses of water daily.	Your hydration needs depend on lifestyle, climate, and other health factors.

Conclusion: Appreciating the Complexity of Water

Water is not a simple, low-energy substance. Its complex molecular structure and the resulting hydrogen bonding give it a suite of remarkable properties that are essential for life as we know it. From its high boiling point and heat capacity to the unique density of ice, water's behavior is a testament to the power of its polarity. Moving beyond simple falsehoods and appreciating these scientific truths deepens our respect for this precious and vital resource.

For more information on the properties of water, explore the U.S. Geological Survey's water science pages.

Frequently Asked Questions

Water is a polar molecule because the oxygen atom is more electronegative than the hydrogen atoms, creating a partial negative charge on the oxygen side and partial positive charges on the hydrogen side. This uneven charge distribution is characteristic of a polar molecule.

The primary reason for water's unique properties is its ability to form hydrogen bonds. The polarity of the water molecule allows the partially positive hydrogen of one molecule to attract the partially negative oxygen of another, creating these strong intermolecular forces.

Boiling water effectively kills bacteria, viruses, and other pathogens, but it does not remove chemical contaminants, heavy metals, or dissolved minerals. For complete purification, other methods like distillation or advanced filtration are necessary.

Ice floats because it is less dense than liquid water. As water freezes, the molecules arrange themselves into a rigid, open crystalline structure, causing the volume to expand. This expansion decreases the density, allowing ice to float.

No, the 'eight glasses a day' rule is a generalized guideline, not a strict requirement. Your actual hydration needs depend on factors such as your activity level, climate, body weight, and overall health. It is often more effective to drink when you feel thirsty.

The term 'hard water' refers to a high concentration of dissolved minerals like calcium and magnesium. While often associated with problems like limescale buildup, these minerals are not harmful to human health and even contribute to bone and cardiovascular health.

Water is known as the 'universal solvent' because its polarity allows it to dissolve a wide variety of substances, particularly ionic compounds and other polar molecules. The partial charges on water molecules can attract and pull apart the ions or molecules of many substances.