In 2006 the World Health Organization published its new Guidelines for the safe use of wastewater, excreta and greywater. Together the Guidelines offer a safety framework, and minimum requirements for the safe use of wastewater, excreta and greywater in agriculture and aquaculture. Anyone interested in safe wastewater management will benefit from getting acquainted with the guidelines. The first volume Policy and regulatory aspects deals with policies and regulations regarding safe water management. It is primarily meant for persons in policy-making positions, as well as for controlling officials. Aside from offering guidelines for example on how to formulate, harmonize and mainstream policies in effect, it also gives an introduction to Volumes 2, 3, and 4 of the Guidelines, by means of executive summaries. In the end of Volume 1 index and a glossary of terms for all the volumes (1-4) can be found. Volume 2 of the Guidelines Wastewater use in agriculture focuses on the health impacts that wastewater use in agriculture has, for instance, on consumers and those who work in this field. The main focus of this volume is thus on safety maximization (such as food safety) when it comes to wastewater use in agriculture. The second volume of the Guidelines is primarily meant for use when developing national and international methods for safe water management. Volume 3 of the GuidelinesWastewater and excreta use in aquaculture also centers on the safety matters, the risks and the benefits this time especially related to wastewater and excreta use. The focus of this volume is specifically on aquaculture. Similarly to Volumes 2 and 3, Volume 4 Excreta and greywater use in agriculture also focuses on the safety matters; however, the center of attention is on agriculture, with a specific view on excreta and greywater use.