D55 wrote:

The law seems to say that the pipework up until it reaches the main sewer is
my responsibilty.

No "seems" about it.

But it can't be fair for a home owner to be held responsible for pipework
that is 8 or 10 feet below ground level beneath layers of concrete!

Whine, whine, whine.

Try being responsible for your own drainage, septic tank and incoming
electricity. Then you can come back and whinge.

BTW, do you not own a spade?