Water and sanitation are, in addition to power supply, considered as the three top critical areas when a natural disaster hits. Decentralised water and sanitary systems are more resilient in stress situations (see also decentralised supply). Planning and implementation of resilient water and sanitary systems that, to a best possible degree, can withstand the climate challenges and effects of natural disasters, particularly for the poorer parts of the population, are therefore needed. The objective of this module is to provide knowledge and to be able to plan and prepare water and sanitation system for pre- and post-disaster situations. The module will help to assess and prioritise water and sanitation needs for a population in an emergency situation, how to be prepared for an emergency and how to take appropriate measures to prevent and control disease outbreak (see also sanitation in emergencies, water purification in emergencies, POU water purification in emergencies, and community and camp water supply).