One major reason for sewer line clogging are tree roots.
If tree roots grow too much, it will combine with the dirt then puncture the pipe and you will not be able to clean it with the snake machine so it would have to be repaired or re-piped..
Second reason of repairing the main drain line is corrosion.
Trenchless sewer line replacement (Bursting style)
We can replace the sewer line by digging 2 points, the starting and ending point. This will only require minimal digging leaving the landscaping above unaltered.
Sewer Line Replacement (Trench style)
Original style with digging N replacing.
P trap is a very important drain system. The water in the P trap prevents sewage gas smell. But the trap arm is very important to keep the water in the P trap. If the trap arm (refer to the drawing) has a slope, all the water in the P trap will drain due to the siphoning. If the trap arm is too long it will clog. Depending on the width of the pipe will determine the length of the arm.
When the trap arm is too long and angled the pipe will easily clog.
The trap arm can not be more than 3' (11/2" pipe) by code
When the P trap is too long and the connection point is under the tee it will leak easily.