WHO published in 1989 the first Guidelines for the Safe Use of Wastewater and Excreta in Agriculture and Aquaculture that were widely used. Since that time, more experience has been gained and more evidence is produced. The new WHO guidelines on water reuse in agriculture, recently published, provide all the basic information on the health risks, and how to set health based targets, by quantifying the risk and developing pathogen reduction targets. Furthermore, an analysis of the health protection measures is included, making reference to the wastewater treatment, crop restrictions, wastewater application methods and human exposure control.