Posted: 19/03/2015 at 12:36
Should not be a problem as long as you remember the rules about what you cannot put down the toilet. (Everything must be bio-degradable).
Once upon a time the contents of the 'earth closet' were used on the garden as fertiliser and people survived.
As Nutcutlet says, the grey water, which is all that should come out of the system, goes into a deep soak away and does not rise to the surface.