Abstract: A head fitting for a bathtub waste water drainage system is disclosed. The head fitting simplifies leak testing in bathtub waste water drainage system and eliminates the need for a separate test cap and fastening hardware for leak testing. The head fitting includes an internal partition wall and a breakout test plug molded as an integral part of the head fitting. The internal partition wall and breakout test plug initially hermetically seal the flow passage of the head fitting for leak testing the drainage system. The test plug can be broken out from the internal partition wall to open the flow passage after leak testing and without damaging the head fitting. The test plug forms part of the partition wall defined by an annular groove in the partition wall. The groove forms an annular band of relatively thin material (fracture band) that integrally connects the test plug to the partition wall, but allows the test plug to be forcefully separated from the partition wall.