Remove the cover. Look inside. If the waste is up to the very top of the pipe, you have a blockage.
Pro tip: Use a metal probe rod. Poke the ground every 2 feet in a line from the house. When you hit concrete or fiberglass 2-3 feet down—bingo. Do not open the main giant lid. That’s where the swimming pool of horror lives. Instead, locate the smaller inlet baffle lid (closest to the house).
Your septic tank is clogged. Not just full (that’s a different beast), but clogged. Solids have formed a dam, or the baffle is blocked. how to unclog a septic tank yourself
The Situation: You flush the toilet. Instead of a graceful swirl, the water rises like a horror movie villain. The shower drain gurgles a desperate goodbye. Worst of all? That smell near the backyard access port.
Just wash your hands four times. Then once more for luck. Remove the cover
You can fix this yourself for the price of a pizza, not a plumber’s yacht.
Now go take a shower—but keep it short. Your bacteria are working. Pro tip: Use a metal probe rod
Now go inside. Flush every toilet. Run every sink for 30 seconds.