How far should a bathtub drain be from the wall? While most plumbers recommend extending it a minimum of 12 inches from the wall, it can go farther.

If you’re DIYing your bathtub installation, you’ll need to begin by cutting a hole in your floor. 

Different tubs have different positions for their drains. Your access hole will need to be cut at the tub’s specific drain end.

The hole you create should be about 9 inches wide, on average. The drain line is exposed with clawfoot tubs, you’ll need to cut with extra precision.

What Is The Standard Bathtub Drain Location?

bathtub drain off a wall

The location of the tub’s drain varies depending on the model. Most rectangular tubs have a drain at one end, and the water flows toward it.

Other models have a drain in the center with a circular sloped floor.

The drain line is threaded up through the floor, so you’ll cut a hole in your floor and pull the drain line through it. This connects to the bottom of your tub to allow for optimum draining.

To figure out where to put your floor hole, drop a plumbing line from the middle of the roll-on your tub’s edge. You’ll see the line touch the floor indicating where you want to put your drain hole for the most efficient drainage system.

Bathtub Drain Measurements

The drain hole should be a minimum of 12 inches away from the wall and 9 inches in scope.

To rough in the drain, use a 1.5-inch pipe. This pipe should have male threads extending a half-inch above the bathroom floor.

Any drain will also require ventilation using a P-trap.

The exact requirements for the size of your vent line, drain line, and trap will depend on local building codes. 

If you’re uncertain about any measurements or requirements, consult with your plumber, you can get some good pointers from a professional.

Similarly, your local plumbing codes will require your drain line to slope away from your tub at a certain angle. The usual minimum is 0.25 inches per linear foot.

Know Your Local Building Codes Before Getting Started

All construction must follow state and local building codes. These codes affect aspects of installing your bathtub drain.

As a general rule, your drain hole should be at least 12 inches from your wall. It can be further, too.

But the further it is from the wall, the more difficult it will be to thread the drain line.

Make sure you’re up-to-date on the drainage codes in your area before you get started. You’ll need to have a certain drainage slope, venting setup, and drain line installation to stay within those guidelines.