What are the signs of septic system problems?

1. Slow or completely plugged drains.2. The yard over the drainage field is soft or a foul smelling and black liquid is coming out of the ground.3. Very lush green grass over the drainage field accompanied by very soft ground.4. Black liquid coming out of the ground above your septic tank5. When you see the the waste level inside your tank higher than 6-10 inches from the top of the tank.   6. Foul odors