 Complete the following phrase:  In natural disasters and other emergencies, the portability of bucket latrines can make them a useful part of an appropriate emergency response, especially where pit latrines cannot be isolated from floodwater or groundwater potentially leading to groundwater pollution and where the contents can be safely disposed into sanitary systems, taking measures to avoid contact with the contents. Different organizations give advice on how to build bucket toilets in case of emergency. The Twin Bucket Emergency Toilet system a two bucket system, for example, has been developed in Christchurch, New Zealand following their infrastructure destroying 