Keep in mind, the exact fittings you’ll need depend on your local plumbing code. We loaded this article with bathroom plumbing diagrams, illustrations, discuss and even a material list…to supercharge your understanding of this basic DWV system. I’m talking drains and vents, the stuff bathrooms are really made of. As a general rule, the drain line for each fixture should connect to a vent within a few feet of the fixture. However, wet venting—routing drain water through a vent—is permitted in some situations. If you are also looking to spend less money on redoing your entire bathroom, you can look at making sure that everything is in the same position so that you do not have to redo too much.