Biosolids are classified in specific State, Territory or national Guidelines. Development of these Guidelines is usually the responsibility of regulatory agencies responsible for the environment. Primarily there are usually two parameters examined when determining the classification of biosolids: the treatment (microbiological) grading and the contamination grading.
Most Australian State guidelines have three or four treatment grades and two or three contaminant grades. The overall combined grade (treatment and contaminant) is usually linked to the different ways in which Biosolids may be used or applied. Grade specifications can be checked with the relevant Guidelines.