How to Plumb a Tub in Concrete

Plan how to run the drain line from the existing roughed-in plumbing or drain. Route the path of the new tub drain line on the floor and mark it with chalk or a similar marking tool like spray paint.

Cut a channel about 4 inches wide into the concrete along your drain path with a jackhammer. Remove all concrete until you hit the dirt beneath the slab. Shovel out the dirt in the channel to make a trench about 3 inches deep.

Attach new ABS pipe to the existing pipe or drain and run it along your channel. Use elbow fittings and couplings to run your drain line as needed. Connect the end of the drain line to the tub drain and set this in the concrete, flush with the top of the floor.

Adhere the pipe, couplings and fittings with ABS glue after the drain line is properly routed.

Add gravel around the tub drain and along your pipe channel as a filler. Install a larger section of 4-inch pipe around vertical section of pipe that attaches directly to the tub drain. Fill the area around the 4-inch pipe and the tub drain channel with mortar and smooth the surface with a tamping tool. Give the mortar 24 hours to dry.