Improperly functioning Septic system

My guess as to the most likely problem is improper slope of the line, which should be whatever the septic design calls for (mine calls for dead level on the distribution lines, but mine is also not a mound system.)

Pipe size and holes should also be as per design - and I'm skeptical of the 6 o'clock holes being correct. Your septic design should be both on-file with the public health department or whoever oversees septic installations/permits in your area, and in your homeowner documentation of your new-built home.

If you don't have a copy of the septic design documents, you should be able to request a copy (probably for a fee) from the permitting authority. You should also be able to get the inspection report from when it was signed off by their inspector.

If the system is built as designed and permitted, then you have an issue with the system designer; if it's not built as designed and permitted, you have an issue with the builder.

The concept of perf pipe and a drainfield is that the pipe has holes on half of the pipe and it’s installed perfectly level with the holes on the top half.

Then, when the liquid flows down the pipe, it fills the entire pipe up until it “overflows” out the holes. That way, the entire septic field gets used ALL THE TIME and very little is deposited in any one location.

Btw, you need an active septic tank so the solids have time to “breakdown” to just liquids so solids don’t plug the holes in the pipe or the drainfield.