Safe use of wastewater, excreta and greywater
A growing world population, unrelenting urbanization, increasing scarcity of good quality water resources and rising fertilizer prices are the driving forces behind the accelerating upward trend in the use of wastewater, excreta and greywater for agriculture and aquaculture.
The health risks associated with this practice have been long recognized, but regulatory measures were, until recently, based on rigid guideline values whose application often was incompatible with the socio-economic settings where most wastewater use takes place.
In 2006, WHO published a third edition of its Guidelines for the safe use of wastewater, excreta and greywater in agriculture and aquaculture. In four volumes, these Guidelines propose a flexible approach of risk assessment and risk management linked to health-based targets that can be established at a level that is realistic under local conditions. The approach is to be backed-up by strict monitoring measures.
In 2015, WHO launched a sanitation safety planning manual to provide step-by-step guidance on implementation of the 2006 WHO Guidelines. The approach and tools may also be applied to all sanitary systems to ensure the system is managed to meet health objectives.
In response to requests from the Guidelines' readership, WHO, together with FAO, IDRC, and IWMI, produced two information kits with targeted guidance notes, discussion papers, fact sheets, and policy briefs, to further clarify methods and procedures. These focus on specific components of the integrated risk assessment and incremental risk management approach proposed by the Guidelines.