Viscosity is a measure of a fluid's resistance to flow. The higher the viscosity, the thicker the fluid and the more resistance it offers to flow.

Water has a relatively low viscosity, meaning it flows easily.

Sparkling water, which contains dissolved carbon dioxide gas, has a slightly lower viscosity than plain water. The dissolved carbon dioxide gas creates tiny bubbles that reduce the fluid's resistance to flow.

Therefore, water has a higher viscosity than sparkling water.