This training manual is the final output of the learning trajectory “environmental sustainability in WASH programs”, being part of the 2016 learning trajectory of the WASH Alliance International. In the first chapter of this training manual the process of setting up the training program is described. This answers the question why a training on environmental sustainability is needed. The second chapter describes the approach and key elements of an environmental sustainable approach towards WASH and includes knowledge we would like the trainees to apprehend and some exercises to increase learning. The third chapter provides an introduction to the importance of a training program taking into account environmental sustainability in WASH programs. This training program has been developed as part of the learning trajectory and targets the planning of new WASH programs. It also provides an example of a setup of a 4-day training program on environmental sustainability in WASH. Especially the third chapter can be used by trainers setting up a training on environmental sustainability in WASH programs.