Abstract: A transparent drain and flush valve component combination detachably connected between a vehicle drain outlet and a disposal conduit which leads to a sewage receptacle. The apparatus includes a main body having a pair of end plates which are joined to the body by fasteners. The end plates and the body are separated by mated flanges adapted to rotate with respect to each other. An elastomeric O-ring between the flanges not only seals but accommodates rotation of transparent attachment pipes for both the vehicle and the disposal conduit. Also, a shut-off valve is included in the body which is manually operated and takes the form of a slide or gate valve which can partially or fully open or close fluid communication between the pair of attachment pipes. A pressurized water supply is selectively attached to an attachment pipe for introducing pressurized water to the vehicle plumbing system, including the holding tank for flushing and rinsing purposes.