A prefabricated former for an underground pump station comprises: a floor former; a plurality of vertical support elements; a side wall secured to and surrounding the plurality of vertical support elements, the side wall having an inner layer and an outer layer defining a cavity therebetween, and an opening at an upper end of the side wall in communication with the cavity for receiving concrete, the side wall extending both above and below the floor former for defining a space above the floor former and a space below the floor former, and an opening being provided between the cavity and the space below the floor former enabling concrete to flow through the cavity and into the space below the floor former; when set, the concrete forming a unitary wall and base.