Existing water reuse standards can be divided into three categories according to origin:
WHO, California and others. WHO-related regulations rely mainly on the document
Health guidelines for the use of wastewater in agriculture and aquaculture, issued in 1989.
Regulations in the USA are State-specific, but the main ones are the California Title 22
criteria (1978) and EPA 1992 recommendations. Other countries (Australia, South Africa)
took the decision to develop their own standards. The most common parameters used in
current regulations are microbiological (Table 1).