Hi, first of all how do you know that your drain lines are blocked? It could be field saturation, distribution box, etc;?
Has anyone ran over the main distribution line or is there a tree nearby the main line?
The first step is to gain access to your main distribution line from the septic tank. You will need to find out where the blockage is. I do this by just running a hose down the main line until I hit the obstruction. I mark the hose, pull the hose back out and then stretch the hose back out again on top of the dirt. This will give you the location of the blockage. I then dig into the problem area and fix the problem. I would say that most all the time I find that someone has ran over the line. Causing a saddle in the line, this causes the main line not to work properly.
You have a main distribution line that feeds 2, 3, or more drain field lines. Most times the main distribution line is the problem.
I also use a steel feeler rod about twice the size of a pencil lead. You can feel the rock in the drain lines by pushing the rod down into the dirt until you hit the rock. This will save you a lot of time and digging.