"Jimk" wrote in message
news
Since our septic tank is under the patio where we sit in the sun,

Cesspit then? Not a septic tank then ?
Unless it has multiple chambers & an outflow to "somewhere"?

Yes, a septic tank. I presume it has multiple chambers.

Aren't there any lids /manholes?

There are several manholes, but I'm not certain which give access to the two
chambers of the septic tank and which are a rodding points to rod the pipes
upstream of the tank. And I'm not about to lift the lids to find out - I
leave that to the "poo fairies" who come to empty the tank and who are paid
to do what must be a very disgusting job.

I still have nightmares about a very sad case I heard of about 50 years ago.
My parents kept their caravan on a farm (the farmer rented land for caravan
owners to leave them there over the winter), and just before we first went
there, the little boy on the farm fell into the septic tank or cess pit and
drowned what must have been a revolting death.