The amount of space (volume) the liquid occupies does not change (actually the volume does change but the change is very tiny). ... Liquids are always considered to be incompressible fluids, as density changes caused by pressure and temperature are small.

Are incompressible fluids real?

An incompressible fluid is a fluid, the density of which remains constant during flow. Liquids are normally treated as being incompressible, as a gas can be when only slight pressure variation occurs.

What does it mean when fluid is incompressible?

In fluid dynamics, incompressible flow refers to a flow in which the density remains constant in any fluid parcel, i.e. any infinitesimal volume of fluid moving in the flow. This type of flow is also referred to as isochoric flow, from the Greek isos-choros (ἴσος-χώρος) which means “same space/area”.