Although a shower and tub drain serve the same function -- to dispose of waste water into your pipe drainage system -- each one performs the task differently. A standalone shower drain and a tub or bathtub and shower combination drain cannot be used interchangeably. If you are remodeling your bathroom and the project involves replacing your standalone shower with a tub, consider hiring a plumber to install the tub. He can ensure the plumbing outlets meet plumbing code.
A shower uses a floor drain, which directly eliminates waste water from the shower instantaneously as you bathe. A tub drain requires you to manually close and open it with a lift-and-turn mechanism or a lever. You push the mechanism down and turn it clockwise to close the drain when you want the tub to fill with water. Once you have finished bathing, you lift the mechanism up and turn it counterclockwise to open the drain and allow the water to drain. A lever works pretty much the same way, except that you pull the lever up to close the drain and push it down to open.
Pipe Connection Size
Shower and tub drains usually have different drain connection sizes to accommodate the various pipe sizes of your home's plumbing drain system. A shower tub drain has a 2-inch drain connection, while a tub drain frequently has a 1 ½-inch drain connection, according to Plumbing Supply. The drain connection for your tub is generally the same as the one for your sink, whereas the shower drain connection is slightly larger.
Since a shower has a floor drain, waste water empties directly into the plumbing drain system. It does not have to be piped from the shower outlet to the plumbing drain system, like a tub drain requires. Ask the Builder says to think of your tub as a floor-level sink. A tub mandates that you install drain connections, similar to those found on your sink, for waste water to empty into your home's plumbing drain system.
If you are in the process of converting your shower stall to a standalone tub or bathtub and shower combination, ensure the installation is to code. A shower drain should pipe directly to a shower outlet, and a tub drain should pipe directly to a tub outlet. Without the correct drain pipe connections, waste water can drain from the tub and accumulate underneath it until it finds its way to the floor drain and eventually to the drainage system, which can create a health hazard.