General

1. From their origin point of view, there are three main sources of natural water: surface water (streams, lakes, ponds), groundwater (wells, springs) and rainwater. From their location point of view, there are two types of water sources: those situated above consumption points (they may be preferable because they may provide water by gravity and will allow for the construction of systems with less operation and maintenance requirements) and those situated below consumption points (the water system will rely on water lifting equipment). Considerations in choosing between alternative sources of water in an emergency include:

i) Volume of supply (See 3.1);

ii) Reliability of supply (taking into account seasonal variations and, if necessary, logistics) (See 3.9);

iii) Water quality, risk of contamination and ease of treatment (See 3.11);

iv) Rights and welfare of local population (See 2.1; 5.1-ii);

v) Speed with which a source can be made operational;

vi) Simplicity of technology and ease of maintenance (See 11.15);

vii) Cost.

2. Take careful account of systems and methods already in use locally. Adoption of well-proven and familiar techniques, combined with action to improve protection against pollution, is often a sound solution.

3. In addition to organizational measures to protect the water supply, some form of treatment may be necessary. However, sources which would require treatment should be avoided if at all possible (See 8.2). The purification of unsafe water, particularly in remote areas, can be difficult and requires trained supervision to be reliable.

4. Gather as much technical information as possible on the different water sources so as to allow simple cost-benefit analysis of alternative solutions. The decision on which sources to develop and the technological approaches to be used should take into account the need for a step-like response to allow maximum use of available resources and the need to develop efficient systems to effectively cover immediate and longer-term needs (See 4.1; 12.4).