While wastewater reuse has been practiced for well over a hundred years as an effective combined strategy for water conservation and water pollution prevention, health regulations in the form of guidelines and standards have developed erratically under the influence of varying historical forces and social trends. In the earliest periods there was little or no regulation. Early in the 20th century with the growing awareness and fear of environmental transmission of communicable diseases the pendulum swung in the direction of extremely severe, and often unenforceable, health regulations which lacked a firm epidemiological basis. This paper summarizes recent research studies and policy reviews sponsored by the World Bank and the World Health Organization which have provided a sound scientific basis for re-evaluating the health risks associated with wastewater reuse and technological and policy guidelines for their control. This more rational and realistic approach based on credible epidemiological evidence has led to the promulgation by the WHO of new health guidelines allowing for unrestricted agricultural irrigation of all crops including vegetables eaten raw, with an effluent standard of 1 or less helminths/liter and a mean of 1000 fecal coliform/100 ml.
