I picked yours to 'quote' because you mentioned a water softener. But, our experiences with a septic system disagree with much of the 'wisdom' imparted here.
When we moved in, the septic system was ten years old and, to our knowledge, had never been pumped out. At least, the subject never came up during negotiations for purchase.
We (two of us) lived here for (about) fifteen years before we wondered what the inside of the septic tank looked like.
I had a local guy come to pump the tank out, and I spent the whole time helping ... or asking questions ... whichever he was willing to put up with.
First thing I noticed was that the tank interior did not smell like I expected. It was a heavy, earthy smell, but not like what we got when 'burning the sierra' in Vietnam.
When I mentioned that to the guy he said it indicated a 'healthy' tank.
When he started to probe the scum layer, he said, "You guys don't use Rid-X, do you?"
I said he was right, but how did he know?
He said that Rid-X causes a lot of scum to build up, and generally advises people to use something else ... or nothing.
We had been using 'nothing' ...
So, anyway, we had a healthy system that (possibly) had not been pumped out in 25 years while we had done nothing special to maintain it other than be careful about what we flushed down there.
We have a garbage disposal in the kitchen, and anything 'vegetable' goes through ... but not meat. We also don't pour cooking oils or greases down the drain.
The toilet paper we use is 2-ply, but is stated to be safe for septic systems. That's the only kind of paper that goes down the drain.
We also have a water softener (already here when we came) which runs (I think) every third day, and uses (I think) six pounds of salt per run.
All of our used water, including 'grey' water, goes into the septic tank.
We did begin using a clogged drain and septic tank 'helper' named Flow!.
We started using it for this reason ...
The ground above the drainfield is covered with grass.
The actual layout of the pipes was very evident when we first arrived because, in the summer, there was extra growth in those long lines.
In more recent years, parts at the distant end don't seem as green as they used to be, so we started using a product that claims to percolate through 'solids' and clear out obstructions.
This is a preventative measure that we hope isn't actually necessary ... as our system continues to work well despite it's age and being 'ignored' for so long.
There is a little poem posted in the bathroom which was there when we arrived.
All us folks with septic tanks
Give to you our heartfelt thanks
For putting nothing in the pot
That isn't guaranteed to rot.
Kleenex is bad, matchsticks too,
Cigarette butts are taboo!
No haircombings - use the basket.
There's a darn good reason why we ask it.
CM