Comparable to a composting system but doubtlessly anaerobic. Would avoid substances such as chlorine based cleaners (bleach), detergents unless 'eco-friendly', excessive amounts of cooking fats and 'other solids' of a synthetic nature. You should be able to detect problems - use a nose!, although correctly functioning systems have a 'flavour' that is not often mistaken. Ensure that the run-off is able to percolate into YOUR ground. It must/should not enter directly watercourses, streams, public areas or that of a neighbour; above ground.