A drain valve and method for assembling a drain valve. A valve assembly is inserted into a pipe, and a reduced diameter portion is formed in the pipe to create a substantially water-tight seal between a portion of the valve assembly and the pipe. A second reduced diameter portion may be formed in the pipe to provide a thrust bearing surface for resisting sliding movement of the valve assembly within the pipe. A transverse hole is provided in the pipe to provide access to a rotatable mechanism in the valve assembly to permit and restrict fluid flow through the drain valve.