"mmzz" wrote in message
om...
I guess it will need emptying in a few years. Its supposed to be the
sort of 80 quid a year call out and pump thing, but I suspect I may
simply get in with a spade and wheelbarrow and dig out most of it and
stick it on the compost heap one day...

is there any reason why this shouldnt be done?

As most septic tanks are to be found in country property where a decent
size garden is the norm and neighbours are country folk with an appreciation
of the ways of nature rather than city bred with a belief that everything
natural should be legislated against and controlled by a raft of beauracracy
(apologies to those who don't fall into this generalisation) then you should
have a marked advantage. The best time to do a planned clean out is Autumn
so the garden gets most benefit from the winter rest period. There will be a
liquor on top of the solids (well more of a pasty silt than solids
actually). In most cases this can be baled or pumped out onto a bit of fresh
dug ground followed by the silt. Do the silt progressively by
baling/shovelling into the trench as you continue digging. Allow the buried
valuable source of Nitrogenous compounds to decompose and weather through
the winter then when spring arrives your soil is valuably enriched. Your
garden produce will be wonderfully enhanced.
Until the development of the chemical industry sh*t of one form or another
was the only fertiliser to be had (long live the Nitrogen cycle) rather than
the unnatural stuff plants are dosed with nowadays.