Basement Bathroom

Creating a bathroom in the basement is not always easy; several issues make plumbing projects more complicated than those on the upper floors. Try to plan your budget, including everything you might need.

The first step should be to contact the local building authorities. With any construction project, especially for a basement, there could be chances of restrictions.

It would be best to locate the new bathroom in the basement as close as possible to the existing plumbing. The ideal solution, if possible, would be to place the bathroom directly under the one upstairs. This makes the operation less expensive and the connections easier to do. You must also consider the type of bathroom you want to create if complete with a shower or more content, such as a service bathroom with only a toilet and sink or adjoining laundry space.

Equipment and early works

Before starting your work, try to have the necessary tools for this DIY project to save time and frustration. You will need safety glasses, protective gloves, hammer, saw, cordless drill, tape measure, level, screwdrivers, ladder, spade, trowel, PVC pipes, fittings, concrete, silicone glue.

Locate the main drain and break through the concrete to verify that the mainline is precisely where you think it is and is deep enough to allow adequate descent into the new drain lines. Once the line is located, you will need to make sure it is deep enough to allow for the downward slope in the new drain lines of your basement bathroom. Then take a pencil and trace the entire bathroom in the basement, i.e., walls, toilet, sink, shower, and drainage points.


After framing the bathroom walls, install the vent pipes. Run them under the floor. Venting is vital because pressure and vacuum are created in the pipe through a discharge line. If not done right, you risk having annoying, very noisy drains. It is also advisable to install a non-return valve to prevent the backup of wastewater in the basement.

Drainage is essential when designing a basement bathroom. The force of gravity provides a push that moves the waste along the pipes. There must be enough drop depth to drain the toilet, sink, or shower in a basement bathroom. If your existing plumbing drain is deep enough, bathroom construction will be relatively easy. If not, a little extra work is needed to break up the floor, remove part of the basement, and dig into the ground below. When digging, keep the topsoil separate from the large concrete blocks; you can reuse them for backfilling later. However, use gravel first, which leaves room for groundwater to penetrate without putting pressure on the floor and avoiding cracks.

If the mainline is not deep enough, you will need to locate the plants closest to the line or install a sewage pump.

Basement bathroom: Special installations and other tips

You may be able to circumvent the breakdown of your foundations by considering unique fitting systems which are comfortable but significantly add to your initial budget.

They can be flush toilets which include a pumping mechanism hidden inside or behind the toilet, composting, or sewage ejection systems. Some flushing toilet systems include a steeping function that reduces waste into small pieces before pumping, eliminating clogging problems.

Also, try to provide good lighting in the basement bathroom. If you locate the room against an external wall that is not entirely underground, take the opportunity to make a frosted glass window and have natural light.