This chapter discusses compelling arguments showing how the low cost aluminum foil opens new and unprecedented opportunities for composite pipelines. It describes the insertion of a thin impermeable aluminum foil between the pipe's resin-rich liner and its corrosion/weep barrier. The impermeable pipes find new and undreamed of applications in the transmission of gases and solvents, while improving their performance in well-established markets like oil and sanitation. The benefit of the impermeable foil lies in the improved damage tolerance of the pipes, which display a higher weep threshold than the regular ones. The impermeable aluminum foil is a welcome low cost solution that eliminates the expensive quality control hydrostatic pressure testing currently required on all sanitation and oil pipes. The foil chemically bonds to the resin to become an integral part of the pipe. The original development of the impermeable pipes contemplated services in high-pressure pipelines for ethanol transmission. It includes underground storage tanks, oil and sanitation pipes.