AbstractProfitable production and sale of rigid PVC water pipe is difficult even in the best of economic times. The industry is intensively cost driven. The development of lower cost formulations is, therefore, of great interest.Conventional pressure pipe formulas do not provide sufficient hydrostatic strength when calcium carbonate filler levels exceed 5 parts per hundred resin (phr). This paper will describe the development of a pressure pipe formulation which contains up to 10 phr filler while maintaining physical properties exceeding all of the required minimum standards.The presentation will include the physical property testing required to develop the formulation including cell classification and long‐term hydrostatic design stress tests. These will be contrasted with data obtained from conventional formulas containing 10 phr of fillers.The quality of commercially extruded pressure pipe made with the new formula will be discussed as a function of raw material selection, blending, and extrusion condition