Here is a picture of the bottom cap attached to my drain plumbing. As you can see, the 3/4" threaded male PVC fitting is definitely cemented into the bottom 4" cap. Just for good measure, the inside of the 4" cap also has a layer of silicone over the connection between the two fittings to make sure that it absolutely will not leak. If you look close, you can see that the V-Tower is tilted slightly backwards to prevent water from splashing out of the slot in the front.