10 Facts About Water You Might Not Know – From a Chemist’s Perspective

Water is the most common liquid on Earth. In the laboratory, we handle it every day — as a solvent, a rinsing medium, or, sometimes, an unwanted source of contamination that can ruin an analysis. In laboratories, we address its purity (overview of water treatment systems from Watrex), but behind this "ordinary" H₂O lies a fascinating world of physicochemical peculiarities. Here are ten facts that might make you see water in a whole new light. 

1. Water is not just H₂O 

In an ideal world, every molecule of water would be pure H₂O. In reality, it also contains a small fraction of heavy water (D₂O), where deuterium replaces hydrogen, as well as various oxygen isotopes (¹⁶O, ¹⁷O, ¹⁸O). These variations can affect reaction rates and vibrational spectra. 

2. Water is the strangest liquid on Earth 

No other known substance behaves quite like water — it exhibits over 70 physical anomalies. For instance, its density peaks at 4 °C (not at freezing), its melting and boiling points are unusually high, and when it freezes, its volume expands, allowing ice to float. 

3. Every drop of water has a different “age” 

Molecules of water continuously circulate through the global hydrological cycle — it can take hundreds of years for a molecule to travel from the ocean back to land. The water you’re using in your lab today may once have been part of an ancient sea or glacier. 

4. Water is a superb solvent — sometimes too good 

Thanks to its high polarity and ability to form hydrogen bonds, water dissolves more substances than any other liquid. That’s wonderful for chemistry, but challenging for water purification: removing every ion, organic molecule, or microorganism is extremely demanding. 

5. Pure water hardly conducts electricity 

Ordinary “conductive” water owes its conductivity to dissolved ions. Ultrapure water (Type I) has a resistivity of 18.2 MΩ·cm, making it almost an insulator. However, even trace amounts of CO₂ from the air quickly lower that resistance.

6. Ice exists in more than 15 forms 

Yes, ice isn’t just ice. Under high pressures and varying temperatures, many crystalline forms appear — from common ice Ih to exotic types like ice VII or ice X, found deep inside planets. Each form has its own molecular arrangement and density. 

7. Water is nature’s best temperature regulator 

Water’s high specific heat capacity and heat of vaporization mean it can absorb or release large amounts of energy with minimal temperature change. That’s why it stabilizes both global climate and body temperature — and makes laboratory water baths so effective. 

8. The pH of pure water isn’t exactly 7 

At standard conditions (25 °C), pure water has pH = 7 because [H⁺] = [OH⁻]. But as temperature increases, water’s autoionization increases too — at 50 °C, the pH is about 6.63. It’s still neutral, since both ion concentrations remain equal. 

9. “Purity” in water means more than absence of dirt 

Laboratory water quality is assessed by conductivity, resistivity, TOC (Total Organic Carbon), ionic contamination, and microbial content. Even microscopic deviations can affect sensitive techniques such as HPLC, ICP-MS, or PCR. 

10. Water molecules are highly “social” 

Each water molecule forms an average of 3.4 hydrogen bonds with its neighbors in the liquid state — constantly breaking and reforming billions of times per second. This molecular “dance” is the key to water’s unique behavior.

Conclusion 

Whether you’re preparing buffers, calibrating an HPLC system, or washing glassware, remember that water is more than just a solvent — it’s a dynamic, complex system influencing every experiment. That’s why controlling its purity and treatment truly matters. 

Do not hesitate to contact us at [email protected] and we will help you choose a suitable water treatment system for your laboratory or provide one-time or regular service for your existing system. 

Tip for laboratories: 

If you found this topic interesting, explore modern laboratory water purification systems from Watrex Praha, designed to deliver precisely defined water types. Pure water = reliable results.