Taking on the project of building a basement bathroom will take some plumbing know-how and knowledge that you will have to break and crack your basement floor. You will have to carve a trench for your tub, toilet or basement shower drain. This will connect the unit's drain to the main basement drain line. If you are going to use a pump system—which means your drain line is above the basement floor level—you will have to get a sump pump drain system installed instead.
Step 1 - Measure the Drain Distances
When building a basement bathroom, you have to locate a place where the used water drains out; this is more important than where the water comes in. If your main line for the basement drain is located in the floor, use the string and pencil to draw a circle 1 foot around from the center of the main drain. You are using the string and pencil as a compass, and you can pretty much do this yourself by hand, or you could get a friend to hold one end to make it easier.
The cement in this area around the drain pipe is going to be removed to allow access to the drain line. (Note: If your main drain pipe is above the floor level, you will need to use a sump system, which this article does not cover.) Measure the distance from the main drain's center to the center of your tub shower or toilet drain's final location. Map this on the floor showing where your basement bathroom drain lines are going.
Step 2 - Break the Floor
To build a sunk-in drain system that connects new drains into the main drain line, you will have to break out the actual cement in the floor to make channels for your piping. Use the cement drill to bore holes through, just on the inside of your channel's measurements, to prevent giant cracks from developing later. Once you have cleared the area around your main drain line and the trench for your incoming drain, you will want to check the plain with your liquid level.
Ensure that the drain on your bathroom unit is higher in altitude than the final main drain, unless your using a basement sump pump system. This allows gravity to take the waste away and not pool up in the basement.
Step 3 - Install Fittings
The last thing is to install your T-Bend on the main drain so that the drain pipe from the tub or shower connects into it at a lower degree than the units themselves. The tub should be at a higher degree than the main drain end to allow gravity to pull wast out of the tub or shower, which means your trench will be lower near the main drain. Use PVC sealant to attach the incoming line to the main drain, and fit your floor drain into the top of your new joint.