In jet pump liquid flow control apparatus the combination comprising an annular body and a liquid flow passage through the body, the passage defining a longitudinal axis; an annular series of flow controlling elements spaced about the axis with successive of the elements having primary portions extending in edge overlapping relation whereby the elements define a flow controlling section of the passage; and control means extending about the axis for controllably urging the primary portions of elements toward the axis thereby to control the cross sectional area of the passage sections.