This paper asks what is good practice in emergency water and sanitation programmes? An innovative feature of the paper is the consideration of good practice in relation to seven scenarios selected to represent the range of situations likely to be faced by relief agency personnel. The first four scenarios involve population displacement into: arid areas; areas of abundant surface water; hilly and mountainous areas; and areas of existing settlement. Two further scenarios discuss good practice in relation to resident populations affected by drought and other natural hazards. The final scenario discusses the role of NGOs in relation to emergency water and sanitation programmes in urban areas.