A vacuum ejector or simply ejector is a vacuum pump, which produces a vacuum through the Venturi effect.

The cheap and simple water aspirator is commonly used in chemistry and biology laboratories and consists of a tee fitting attached to a tap and has a hose barb at one side. The water flow passes through the straight portion of the tee, which has a restriction at the intersection, where the hose barb is attached. Therefore, the vacuum hose should be connected to this barb. In the past, water aspirators were common for low-strength vacuums in chemistry benchwork.