Posted: 22/03/2014 at 23:45
Wait a moment. The OP did not say raw sewage was coming into his garden.
No one but a complete fool would put bleach, unsuitable lavatory cleaners and paint solvent into a septic tank. This has just been made up to embellish the story.
It's not so very many years since 'night soil' was spread on the fields and certainly was used in the vegetable garden. Since when did everybody get so precious about a bit of s**t.
Yes, it will have to be sorted, but during my long life I have only been on main drainage for one very short period, and I am still here to tell the tale.
And one good thing is we pay so, so much less to the Water Board than those of you with public sewers!