A hillbilly shack in the jungle...

[Dougal]

That's what I thought Dr Andy. Hope I'm not wrong...

I think that is the main thing about a septic tank, the shit has to gently stew and degenerate. When new shit comes in, it pushes the older shit out to the next tank, or ring, where it should get completely broken down. It is then safe to slowly soak into the ground, bacteria free.

There must be some good info about this somewhere

The one I had put in, in Portugal, was a single tank, but inside was a series of concentric rings which the shit had to flow through. At the end, it discharged into the same soakaway as the grey water

There is a whole thread on Septic tanks here:

https://teakdoor.com/construction-in-...-thailand.html

One of my posts in there has some links to other sites that tell you more than you ever wanted to know about getting rid of shit.