The name of the Unit clearly illustrates some of the principal challenges facing humanitarian assistance and development activities in the new millennium. Water is already a major issue for modern-day civilizations, and in the future will become increasingly important. Meanwhile, habitat is a term which designates not merely the boundaries of the home, but its relationship with the wider environment and the people who live in it. At present millions of people throughout the world have difficulties gaining access to clean drinking water, proper housing or to decent sanitation in times of peace, and will not do so for the foreseeable future. Access to water and housing may also become problematic both during and after a conflict.

In the heat of a battle, water sources may be deliberately targeted; it may be that people have to leave their homes and seek water in hostile environments; or it may be that the infrastructure that provided water is damaged in the fighting or becomes out of bounds for other reasons. A dramatic increase in waterborne and water-related diseases (diarrhoeal diseases, typhoid fever, cholera etc.) are the immediate signs of the failure to deal with these problems. The knock-on effects are also clearly visible. Water shortages reduce food production, aggravate poverty and disease, spur large migrations and undermine a State's moral authority. As water and habitat are so essential to survival, ensuring access remains a priority for humanitarian organizations.

ICRC water and habitat assistance includes construction, engineering, providing access to water, hygiene and environmental protection. These must all be viewed as being mutually complementary, and in the field they often call for the same technical approach. ICRC programmes conducted since the early 1990s have revealed a growing tendency to include programmes in urban areas, entailing more sophisticated and costlier projects, particularly for water treatment, purification and distribution systems. This has resulted in closer links between specializations such as hydraulic engineering, hydrogeology, environmental, chemical, electrical and civil engineering.

The Water and Habitat Unit's growing palette of activities:

Access to water
- rehabilitation of water treatment plants, distribution networks or gravity water systems linked to pumping stations;
- construction of wells; harnessing and protection of water sources and drainage systems; construction of water-storage containers;
- purification and distribution of drinking water (i.e., water-trucking, standpipes);

Waste disposal / Hygiene
- construction and rehabilitation of latrines and sewage treatment systems; programmes for the collection and treatment of waste, including hospital waste;

Construction/Engineering
- renovation and reconstruction of health structures and schools; renovation/rehabilitation programmes in places of detention; building and conversion work to camps for displaced people; material assistance for construction purposes intended for families returning to their places of origin (for housing, heating, cooking etc.);

Environmental protection (air, soil, river and groundwater)
- vector-control programmes; protection of foodstuffs; decontamination of living spaces; reduction of energy consumption; use of alternative energy.

Examples of the different times during the crisis process when the Unit might respond and the effect of water and habitat assistance over the long-term:

The graph above shows the impact of preventive water and habitat projects initiated before a deteriorating system drops below the emergency line, that is, before morbidity and mortality increase due to the collapse of the given system. These projects are medium- or long-term, and if successful, ensure that the system remains operational. (A "system" here may refer to housing, water treatment and distribution, vector control, energy for cooking etc.).

Sudden destruction of a system, or political and security constraints may cause it to fall below the emergency line. Survival is then threatened and emergency water and habitat projects are the only solution. Such programmes often need to be repeated because the system can not be stabilized at a reasonable minimum level and may again drop below the emergency level, as shown in the graph below.