Installing new fixtures requires
careful planning; even small
errors can lead to problems.

About this Project

Most improvements the do-it-yourselfer will make are add-ons, where you simply hook new fittings or fixtures to existing pipes. Running new lines takes coping with the constraints of your situation and an understanding of how supply, drain, and vent pipes work.

New supply lines are the easiest to plan. They require no slope or venting, just the correct pipe size (see Measurement Tip). You can run them wherever you need them.

Far trickier are the drain-waste-vent (DWV) lines that carry away water, waste, and gases. The illustrations below and on Venting Possibilites show straightforward ways to tap in for a new fixture. Your situation may not be this simple and may require the skill of a professional.

For any new installation, even a minor one, you'll probably need to apply to your local building department for a permit and arrange with them to have the work inspected before you cover up any new pipes.