Use PVC for drains. You can use 1.5 inch and 3 inch. From the toilet bowl to the septic it needs to be at least 3 inch. Smaller pipe can connect together to the bigger one on the slope down. Make sure your tees have the inside bend going with the flow. This will be towards the larger pipe or septic.
Make sure you plan for a vent. It should be the size of the largest pipe you use. Put it at the point directly upstream from where the larger pipe starts. It goes up through the roof (with appropriate flashing).
All pipe should slope about 3 inches in ten feet (where possible).
Get the needed fittings. Elbows(90,45,22.5), Tees and couplings.
Cut the needed straight parts with a chop saw and a fine tooth blade. I do mine with a sawzall, but you need to make sure the pipe ends are square and free of burrs.
Test fit all the pieces in place, nice and tight, and mark them with a sharpie. Make the marks so you can see them (bottom side). This will ensure that your new piping goes where the pieces fit.
Mark where the female collar hits the male pipe and an alignment mark. Make sure that you have at least 3/4 inch between the mark and the end of the pipe.
If there are a lot of pieces, you can mark the ends. A-A, B-B, etc.
Take them apart and place them on the floor in order of assembly.
Wear gloves. Be quick as you have a few minutes to get the joint together.
Start from one end and work your way to the other. Use primer on the "female" end and put glue around the tip of the "male" end about 3/8 of an inch. Rotate the pieces as you turn them and slide them together. Hold the piece in place for 1 minute. Move to the next piece using hangers as needed to support the pipe.
The drains are super low pressure, but can leak if not glued properly. Open a window while you glue the pipe.
Last edited by hasmat
on Thu Mar 17, 2016 11:04 am, edited 1 time in total.
Reason: added vent info
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