Avoid stopping your septic tank
The only difference between blocking your drain and stopping your septic tank is that the drain is a relatively easy fix.
There are no differences between septic tank users and sewerage system users when it comes to drains. See the page Avoid blocking your drain if you haven't already seen it.
In a sewerage system, the stuff goes into tanks and ponds where it is filtered and the rubbish is removed. Then it's left for the bacteria to clean it.
In a septic tank, nothing can be removed. The bacteria have to live with whatever you put down there.
But what if the things that would be removed in a sewerage system cause your tank's bacteria to die?
Then the natural decay stops, and the tank stops working, and you have your own version of the "Great Stink".
See our flyer Keep a Healthy Sewer Near You (88k pdf) for details of the "Great Stink", under History Note.
You've got to get it working again urgently, and dropping in a dead possum might not do the trick this time.
How do you avoid stopping your septic tank from working?
Don't put the wrong things into it.
Next
Putting the wrong things into the drains, the details
What you should do instead, the details
(If you haven't already, see also Avoid polluting the waterways.)