Steve Firth wrote:

Grunff wrote:


All septic tanks need emtying. It may take you 10 years to fill yours,
but you can't wait that long because by that time the solids at the
bottom will be really, really solid. Empty it every 2-4 years.


Just had ours emptied after eleven years. The man from the company asked
why we were emptying it, because there was little sludge and it was all
working fine. Before it was emptied, it never stank, after emptyign it
honked like nobodies business for several weeks. So I don't think I'll
empty it again, ever.

Septic tanks fill very rapidly, depending (obviously) on amount of waste
sent down the drains. We are talking weeks if a large family, not
months let alone years. However the point is that the "overflow"
providing it is treated properly (eg no bleaches, biological detergents)
then should be clear water, which then goes into a soak away, causing no
problems.
As a child I lived in a bungalow built in 1938 with a septic tank, which
was not emptied for the first time until the early 50s, it never gave
any problems.