Abstract: A system for temporarily sealing bathtub overflow plumbing and waste water plumbing to provide for pressurized testing to locate leaks includes a rigid unitary stop for mating with a corresponding female coupler so as to sandwich therebetween a rim of a bathtub aperture. The female coupler has an internal thread in a cavity in the coupler. The female coupler is adapted for mounting into overflow and waste water plumbing for a bathtub. The female coupler is mountable so as to be adjacent the bathtub apertures. The stop includes an annular rigid sealing flange. An externally threaded cylindrical plug is mounted to the sealing flange. The plug is sized to snugly mate into the female coupler in threaded engagement therein. The threaded engagement draws the sealing flange towards the female coupler sandwiching the bathtub therebetween.