Dehydrationmeans to remove water. Therefore, unlike composting, dehydration is the controlled physical process of dewatering moist materials. Dehydration is effective if faecal materials are separated at source without any dilution, since a great part of the liquid phase of faecal materials has not to be evaporated off at all. Therefore, urine diversion is crucial for dehydration. Esrey et al. (1998) claimed that treatment methods based on dehydration can reduce pathogens effectively. There is a rapid pathogen destruction at moisture contents below 25 %. Dehydration processes can be accelerated with the help of heat (solar radiation), ventilation and the addition of dry materials.