Safe irrigation methods are essential when using wastewater for irrigation, but they need to be complemented with other practices from farm to fork to ensure the safety of others involved in the value chain. In 2006, the World Health Organization (WHO), together with the Food and Agriculture Organization of the United Nations (FAO) and the United Nations Environment Programme (UNEP), adopted a multiple-barrier approach to reduce the health risks to farmers and consumers posed by using wastewater in agriculture. This approach opened the door to targeting a variety of entry points where health risks occur or can be mitigated before the food is consumed. This second edition of the handbook focuses on low-cost and low-tech on-farm wastewater treatment and safe irrigation practices that farmers can adopt to grow safer products.