Water Purification in Emergencies Overview

The health of survivors of a natural disaster is exposed to high risk – even if the actual disaster was of short duration. In most disasters and other emergencies, the main health problems are caused by poor hygiene due to insufficient water supply and the consumption of contaminated water (THE SPHERE PROJECT 2011). Water and sanitation (see also sanitation in emergencies overview) are critical determinants for survival immediately after and during the initial stages of a disaster (GWC 2009). Therefore, the availability of sufficient clean water in the immediate aftermath of a disaster is crucial in order to take care of the sick, provide for human consumption and maintain basic hygiene, support search and rescue efforts, and ensure that productive and commercial activities get back to normal. In addition, the lack of water and water facilities often adversely affects the dignity of those caught up in emergencies (GWC 2009).

The general objectives of emergency water supply and purification are (CHALINDER 1994; THE SPHERE PROJECT 2011):

• To protect water sources in order to minimise the risk of contamination and transmission of water borne diseases (immediate objective);
• To provide water of a reasonable quantity (immediate objective);
• To improve the physical and biological quality of the water (medium-term objective);
• To improve access to supplies through improved water distribution networks and storage facilities (medium-term objective).

After a first assessment of water needs and water sources as well as existing water distribution networks, the optimal of immediate response is chosen depending on the local conditions and implemented. However, upgrading of the systems for long-term water supply and reconstruction has to be considered already at the beginning.

Immediate Assessment of Water Supply

The first step to provide water in emergencies is an immediate assessment. Questions to be asked are: How many people need water? What are the problems related to water availability and quality now and how will the situation evolve in some time? Which surface or groundwater sources in the area are affected? How is the water quality of these sources, what is their capacity and how far are they away? How can this water be brought to the people in need and what are the possibilities for treatment if required (see also DAVIS & LAMBERT 2002, table 11.1 for a detailed list of questions to be asked)?

The concrete measures to be taken after a disaster depend on the answers to these questions, the geographical and climatic context (cold or warm weather; draught or flooding); the reason for people being without water and type of target groups (refugees, internally displaced persons, returnees who may temporarily be accommodated in camps or temporary housing, or populations whose lives have been modified by the emergency, but have not been displaced, HOUSE & REED 1997).

The on-going assessment of water needs is divided into four typical emergency phases (DAVIS & LAMBERT 2002; CLASEN & SMITH 2005):

• Immediate emergency phase, the 1-2 weeks following the event;
• Stabilisation phase, typically starting 2 or 3 weeks from and up to 2 months after the event;
• Recovery phase, taking several months;
• Settlement phase, lasting perhaps years.

Minimum Standards

The standard needs established by the Sphere Project consider 7.5 to 15 litres per day as the basic water needs per person per day in emergencies (THE SPHERE PROJECT 2011). In some situations, only water used for drinking and preparing food needs to be treated, which still amounts to 5.5 to 9 litres (KAYAGA & REED 2011). In refugee situations, the UNHCR calculates 20 litres per person per day for domestic needs and personal hygiene. The absolute minimum amount of water required for survival is 7 litres.

The basic survival water needs according to the humanitarian standards defined by the Sphere Project. Source: THE SPHERE PROJECT (2011)

Communal building water needs (e.g. hospitals, administration, etc.) will require extra water (UNHCR 2007). In a refugee/IDP camp these include (UNHCR 2007; WISNER & ADAMS 2002):

• Health centre, field hospitals, first-aid stations: 40-60 litres/patient/day
• Feeding centres: 20-30 litres/patient/day
• Schools: 3 litres/pupil/day
• Mosque: 2-5 litres/person/day
• Hand washing at communal latrines and offices: 1-2 litres/user/day for hand washing, and 2-8 litres/cubicle/day for cleaning
• Operation of water-borne sewerage system: 20-40 litres/person/day
• Livestock accompanying displaced persons/refugees: 30 litres/day/cow or camel, 15 litres/day/goat or other small animal.

Moreover, basic water needs vary depending on climate, individual physiology of affected people, social and cultural norms, and the degree of displacement (THE SPHERE PROJECT 2011; CHALINDER 1994). Leakages and other losses of water in the catchment, treatment or distribution process and spare capacity for possible new arrivals in a camp situation are to be considered. The more convenient the supply, the higher will be the consumption (UNHCR 2007).

Water Supply and Purification in Emergencies

Depending of the availability of water sources and the needs, different options are going to be chosen and for each type of source and type or predicted use (e.g. cooking, washing, medical care, etc.) the right treatment is considered.

The water may be brought to people in need by existing water distribution networks, which may need to be repaired. Either the water is then distributed at water points with or without treatment (see also camp water supply or water purification in general) depending on the use (e.g. drinking, cooking, washing, etc.). In some cases, organisations also choose to promote point of use treatment that users can apply themselves after they have recovered the water manually from the water points or a water tanker. If distribution via a network is not possible, motorised distribution is a very common method in the first phase of emergencies. However, if possible tinkering water should be avoided, as it is expensive and difficult to organise. Water tinkering should be seen as no more than an interim measure to allow for the development of new water sources or the improvement of existing supplies. If there is no viable solution to the water problem, then people should be relocated (DAVIS & LAMBERT 2002).

Comparison of semi-centralised (camp water supply) and small-scale supply in emergencies (first response). 

It is important to note that in emergencies, the securing of appropriate water quantity is prior to securing that water quality is at safe drinking water level. Quantity is more related to water sources selection (availability, proximity and sustainability of sufficient water quantity), while quality affects hygiene promotion and all aspects of water safety plans (THE SPHERE PROJECT 2011).

Simply providing sufficient water will not, on its own, ensure its optimal use or impact on public health. In order to achieve the maximum benefit it is imperative that disaster-affected people have the necessary information, knowledge and understanding to prevent water- and sanitation-related diseases and to mobilise their involvement in the design and maintenance of those facilities. Generally, WASH emergency programmes aim at the above mentioned objectives through (THE SPHERE PROJECT 2011):

• The promotion of good hygiene practices;
• The provision of safe drinking water;
• The reduction of environmental health risks;
• The conditions that allow people to live with good health, dignity, comfort and security.

In case emergencies require or trigger international humanitarian interventions, the availability of material resources and organisational preferences often dictate the solutions chosen for emergency water supply in the field. These variations typically include (HOUSE & REED 1997):

• Organisations may send in equipment to ensure a speedy response but neglecting a thorough assessment. Several organisations have their own modular kits, which simplify the process of equipment selection, installation, operation, and maintenance. These modular kits include pumps, treatment options, water tanks, and distribution systems including pipelines and tap stands (see also camp and community water supply in emergencies).
• Some organisations also have modular mobile treatment units, which are very expensive but useful in the immediate stages of an emergency, especially for industrially polluted water or to supply specific units such as health centres (see also camp and community water supply in emergencies). The kits are used to treat either surface or groundwater from a nearby source, from an existing distribution system or water that has been brought in by water trucks.
• Other organisations prefer to use local materials, methods, and skills wherever possible to benefit the local population and to improve the effective operation and maintenance of systems in the long run. This usually means that semi-centralised water treatment units are gradually installed while short term point-of-use water treatment is promoted.