What are 10 things that cannot dissolve in water?

What Doesn’t Dissolve in Water—and Why It Matters

Water is often called the "universal solvent" because it dissolves so many substances. But not everything breaks down in it. Some materials resist water’s dissolving power due to their chemical nature, and understanding this helps explain everything from cooking to environmental science.

Oils and fats, like vegetable oil or butter, are classic examples of water-resistant substances. Because they’re nonpolar, they don’t interact well with water’s polar molecules—hence the saying “oil and water don’t mix.” The same goes for petrol and benzene, which are also nonpolar and remain separate when combined with water.

Certain ionic compounds also stand firm. Silver chloride (AgCl) and lead(II) sulfate (PbSO₄), for instance, have such low solubility that they’re often used in lab tests to identify ions. Their tight crystal structures resist water’s pull.

Then there are covalent solids. Sand, made of silicon dioxide (SiO₂), might get wet, but it doesn’t dissolve. Likewise, graphite and diamond—both pure carbon—maintain their structure in water thanks to their massive network of strong covalent bonds.

And let’s not forget metals. A copper wire or iron nail won’t dissolve in water under normal conditions. While some metals react with water (like sodium), most remain intact, which is why we can use metal tools and structures in wet environments.

These insoluble materials play vital roles in nature and industry. From the sand under our feet to the fat in our food, their resistance to water helps shape the world around us—proving that sometimes, not dissolving is just as important as dissolving.