Community and Camp Water Supply

Water and sanitation (see also water supply and purification in emergencies and sanitation in emergencies (see PPT)) are critical constituents for survival immediately after and during the initial stages of a disaster (GWC 2009). Therefore, the availability of sufficient water of the highest achievable standard in the immediate aftermath of a disaster is a crucial factor to take care of the sick, provide for human consumption, safeguard basic hygiene, support search & rescue efforts and ensure that both the productive and commercial activities get back to normal as fast as possible.

Where larger groups of people are displaced, either by conflict or by natural disaster and they are likely to stay in a particular location for periods in excess of a few weeks, there will be a need to establish and probably subsequently upgrade a centralised water treatment and supply system (OXFAM 2001). There are many types of water treatment and purification systems available, however, the methods are not too differing. The choice of the most adequate system depends on the number of people to be delivered with treated water.

In general, untreated water is abstracted from a surface water source or directly from an existing distribution system and accumulated in a storage reservoir. The initial treatment process consists of filtration or sedimentation to remove particulate matter from the untreated water. Then, a disinfection process is conducted (usually chlorination) to kill any remaining bacterial and viral pathogens from the filtrated water. Under some conditions in the field, untreated water might require other treatments steps to reduce odour, high bacteria counts, etc. (HOLLAND & GARLAND 1989; HOUSE & REED 1997; UNHCR 2008).

The difficult circumstances in emergencies often pose an assortment of challenges to Emergency Water Treatment Equipment (E.W.T.E.) (HOLLAND & GARLAND 1989):

• Where the units are used to treat water with high turbidity, high algae content, high iron content, high salinity, or containing oil residuals;
• Where the units are located at water sources remote from a convenient point of distribution;
• Where size and weight of the module components (of the E.W.T.E. unit) limit transportation of equipment;
• And where the E.W.T.E. units are not equipped with sufficient additional apparatus to allow operators to adapt to local constraints.

In emergency situations, Mobile Water Treatment Equipment (M.W.T.E) (pre-assembled) and modular water treatment kits (to be assembled in the field) are used to produce drinking water. Treatment systems differ in terms of the type of the raw water (i.e. fresh or salt water and ground- or surface water), the underlying process (i.e. mechanical, physical or chemical) and the mechanism of delivery (pre-assembled or to be assembled in the field). Most larger relief organisations, governmental relief agencies or respective military divisions, have their own selection of modular kits and mobile units (HOUSE & REED 1997).

Different procedures of water treatment:

• Filtration of fresh water by pre-assembled mobile water treatment units water (e.g. PWN Technologies or Katadyn filters)
• Filtration of salt or brackish water by mobile water treatment units
• Coagulation-flocculation and disinfection of fresh water by modular water treatment kits.

Today, many manufacturers offer water treatment units and water kits on the global market and technology development enables on-going improvement of the apparatus. The products presented here are randomly chosen to explain technology. Technical data provided by the manufacturer has not been verified.

M.W.T.E’s (pre-assembled), mounted on trailers or in shipping containers, usually combine coagulation, filtration and disinfection, or simply filtration and disinfection. These units can provide 4'000 to 50'000 litres/hour. They can rapidly produce water of high quality without the need to design and construct semi-permanent water treatment facilities. However, they are expensive to have on-hand for emergency use, and they require a water source near the affected area, as well as specialist technical expertise for operation and maintenance. Individual trainings for operators in the field are required and often different system fittings (e.g. for pipes) are not system compatible (WISNER & ADAMS 2002; HOUSE & REED 1997).

Adapted from: WHO (2008)

To generate drinking water from salt or brackish water, membrane processes such as reverse osmosis, ultra filtration, micro filtration and nano filtration are used. These processes have traditionally been applied to the production of water for industrial or pharmaceutical applications but are now more and more being implemented for the process of drinking water treatment (e.g. TRUNZ Water systems).

Small-scale desalination units have found application in emergencies in recent years providing drinking water to households or communities. They present specific challenges to continue effective operation through maintenance procedures (one consideration is their high energy requirement). Generally, the number of such desalination units is increasing and it is likely that this development is continuing due to increasing water scarcity. Brackish water from sources such as lake and sea may contain particulates not encountered in freshwater systems such as algal content and chemicals, such as boron and bromide, which is often abundant in seawater. The effectiveness of some of the processes employed in desalination to remove some substances of health concern remains inadequate.

Modular water kits (to be assembled in the field) for use in emergencies are robust, easy to assemble, lightweight, pre-packaged, portable by road or air, and can produce once operational up to 600’000 litres/day (IFRC 2008). They come complete and ready for installation, and are designed for installation on location within hours of arrival by a team of semi-skilled workers with some supervision by an experienced engineer. They can be easily disassembled, moved and reassembled. The kits used by a number of different agencies are compatible thanks to the inclusion of a range of types and sizes of pipe fittings (WISNER & ADAMS 2002; HOUSE & REED 1997). These systems do not treat salt or brackish water.

As an example, the International Federation of Red Cross (IFRC), disposes of different kits and so-called Emergency Response Units (ERU) to respond to water, sanitation and hygiene promotion needs in emergencies. Choice is made based on location of the emergency, number of beneficiaries, types of intervention, water volume and services required. If the response has to supply water to more than 10’000 beneficiaries, IFRC deploys the ERU, which includes supporting professionals (IFRC 2008).

Another similar system is advertised by Scan Water. According to its manufacturer, it produces up to 4’000 litres per hour. Hence, it is suitable for refugee camps, villages, military applications. It has been used by UN agencies, Red Cross Societies and other international agencies throughout Africa, Asia and South America since 2000 (SCAN WATER 2011). The system is characterised by simple operation, effective removal of turbidity and a favourable price–performance ratio (IFRC 2005).

A diesel-driven pump draws water from the water source. The unprocessed water is then pumped through coagulation and flocculation chambers to the sand filter stage via a minimum 60m of pipe network to ensure proper flocculation. Then,  the water is pumped through a carbon filter and through an in-line chlorination unit (with an optional liquid feed device). After chlorination, the water is pumped into a number of 10’000 litre pillow tanks. Finally, safe drinking water is supplied from water tap stations (SCAN WATER 2011).

Once the water has been treated by one of the semi-centralised treatment units described above, it has to be distributed. Commonly, water is distributed efficiently within the community or camp using a pipe network. Where possible, the distribution network should incorporate a water storage tank. The tank may be filled slowly over a 24-hour period allowing people to draw suitable water quantities on demand. Residual chlorine is generally added to ensure that no harmful micro organism grow in the water after treatment before it is consumed. Alternatively, distribution conducted by water tankers can be suitable as a short-term measure in case transport means and infrastructure are in an acceptable condition and personnel is available.

The water-collection point usually comprises a series of taps attached to the end of the pipe network. Tap stands should be evenly distributed throughout the camp, and must be strong enough to withstand frequent and intensive use (REED & SHAW 1999; UNHCR 2007).

In a refugee camp, there should be a tap ratio of 1 tap per 80 to 100 refugees. Apart from adequacy, equity, satisfactoriness and safety of distributed water, the following aspects of managing water distribution should be considered (UNHCR 1992; UNHCR 2007):

• Minimise social costs (burden) on the users: Facilities located centrally and not too distant from the dwellings, reduced waiting time and incorporating user-friendly design.
• Ensure physical safety of the users: Facilities located in a secure physical environment; water distribution time planned according to users’ convenience and cultural habits and day-light hours.
• Participation of stakeholders: Refugees and sectors (health, physical planner, sanitation) involved in water system development and operation. Maintaining a good rapport with the host community should be taken into account.
• Control distribution points: In case water has to be rationed, equitable and need-based distribution must be implemented by controlling the distribution points at all time. Consideration should be given for the water sources.

Adapted from: CLASEN & SMITH (2005)

In a limited number of areas, mobile water-treatment purification plants (including desalination plants) and portable coagulation/disinfection systems were brought in and utilised to produce large volumes of potable water (especially in the stabilisation phase, see also water in emergencies). In most cases, produced water was used to fill tanker truck for further distribution. Nevertheless, some purification plants were positioned near camps for direct supply. Thereby, water was stored in bulk in corrugated steel "Oxfam" tanks, collapsible bladder and onion tanks and distributed using rigid or fire hoses.