By D. S. Lantagne, PE

A great deal of progress has been made over the past decade in the field of household water treatment and safe storage (HWTS) in developing countries to reduce diarrheal diseases. Research has shown that the use of five HWTS interventions – chlorination, flocculation/chlorination, solar disinfection, ceramic filtration and biosand filtration – improve the microbiological quality of stored water and reduce the risk of diarrheal diseases (Clasen, 2007; Sobsey, 2008). Non-governmental organizations (NGOs), private companies and government ministries are currently scaling up HWTS programs to reach additional users and reduce the burden of diarrheal disease in developing countries.

One proven intervention, the Safe Water System (SWS), was developed in the early 1990s in response to epidemic cholera in South America by the Centers for Disease Control and Prevention (CDC) and the Pan American Health Organization (PAHO). It consists of three elements: POU water treatment with a locally-manufactured dilute sodium hypochlorite (chlorine bleach) solution; safe storage of treated water; and behavior change communications to improve water and food handling, sanitation and hygiene practices in the home and in the community.

To use the SWS, families add one full bottle cap of the solution to clear water (or two caps to turbid water) in a standard sized container, agitate and wait 30 minutes before drinking. This fixed dosage has been shown to be effective at maintaining less than 2.0 mg/L of chlorine residual one hour after treatment and greater than 0.2 mg/L of chlorine residual 24 hours after treatment in 86.6 percent of 82 samples with turbidity lower than 10 NTU or from a protected source from samples in 13 developing countries (Lantagne, 2008). This dosage has also been shown to maintain correct chlorine residuals in 91.7 percent of unprotected sources with turbidity 10-100 NTU. This dosage is not recommended for source waters with greater than 100 NTU turbidity.

In randomized controlled trials, the SWS reduced the risk of diarrheal disease in users ranging from 26-84 percent (Semenza, 1998; Quick, 1999; Quick, 2002; Luby, 2004; Crump, 2005). At the concentrations added, chlorine is effective at inactivating bacteria, some viruses and some protozoa (CDC, 2008); however, it is not effective at inactivating certain protozoa, such as cryptosporidium. In one study conducted in Kenya, turbid water treated with the SWS did not exceed World Health Organization (WHO) guideline values for disinfection by-products (Lantagne, 2008).

A recent review estimated that 10.4 million people use the SWS for water treatment in developing countries (Clasen, 2008). The largest implementer of SWS programs, a social-marketing NGO, Population Services International (PSI), sold over 12 million bottles of sodium hypochlorite solution in 19 developing countries in 2007 alone, treating over 12 billion liters (3.1 billion gallons) of water (PSI, 2008).

The principal focus of the SWS program over the past decade has been the establishment of products and programs in developing country settings that are intended to provide users with sustainable means of treating drinking water until they can be reached by piped, treated water. However, the SWS has also been used extensively in emergency situations.

The health impacts of the three main types of emergency situations (disease outbreaks, natural disasters and complex emergencies) will be discussed in this article. Descriptions and lessons learned from SWS programs implemented in response to each of these types of emergencies will be presented.

Disease outbreaks
“A disease outbreak is the occurrence of cases of disease in excess of what would normally be expected in a defined community, geographical area or season. An outbreak may occur in a restricted geographical area, or may extend over several countries. It may last for a few days or weeks, or for several years” (WHO, 2008).

Common waterborne disease outbreaks include cholera, typhoid fever, shigellosis, dysentery and those related to hepatitis A and E viruses. Cholera is a serious epidemic disease requiring notification to the WHO under the International Health Regulations (WHO, 2008) and recent data shows that cases of cholera are increasing, particularly in Africa.

In 2006, a total of 236,896 cholera cases, including 6,311 deaths (case fatality rate of 2.66 percent) from 52 countries were reported to WHO (WHO, 2007). This represented a 79 percent increase in cases from 2005 and a three-fold increase in deaths.

Of the 75 outbreaks of diarrheal disease verified by WHO in 2006, 46 (61 percent) were confirmed cholera outbreaks, 44 (93 percent) of which were in Africa. These figures likely represent only a small fraction of the cholera disease burden, as WHO estimates that only 5-10 percent of cholera cases worldwide are reported, due to inadequate surveillance systems and under-reporting motivated by fear of trade sanctions and lost tourism.

Natural disasters
Natural disasters are “catastrophic events with atmospheric, geologic and hydrologic origins,” that include “earthquakes, volcanic eruptions, landslides, tsunamis, floods and drought” (Watson, 2007). Natural disasters have serious health, social and economic consequences, particularly in developing countries, which are disproportionately affected because of fewer resources, less infrastructure and less preparedness.

Although many myths surround the increased risk of outbreaks in post-disaster situations (de Ville de Goyet, 2000; Watson, 2007), the reality is that deaths associated with natural disasters are predominantly blunt trauma, crush-related injuries or drowning and victims are triaged and treated primarily by local survivors before the arrival of international aid. The two situations in which natural disasters have been shown to lead to increased diarrheal disease burden are flooding events and when the disaster leads to large-scale population displacement (Noji, 1997).

Diseases seen in flooding emergencies and events that lead to displacement are generally concurrent with local background causes of morbidity and mortality and include cholera and other diarrheal disease as well as hepatitis A and E infections. Thus, the provision of safe water and sanitation to prevent these diarrheal diseases is the number one health priority in these situations (Watson, 2007).

Complex emergencies
In contrast to natural disasters, which generally are single external events that a population recovers from over time, ‘complex emergencies’ are longer-term emergencies with political causes and consequences. The actual definition of a complex emergency is not as clear as for natural disasters and definitions range from “a humanitarian crisis in a country, region or society where there is total or considerable breakdown of authority resulting from internal or external conflict” (IASC, 1994) to “complex emergencies are associated with crises in governments and in systems of governance and with violence against civilian populations” that “involve an intricate web of political, economic, military and social forces engaged in violence” (Lautze, 2004).

The effects of complex emergencies on the civilian population are clear, however, as these emergencies impact livelihood and lead to increased morbidity and mortality from “preventable and treatable illnesses.” These illnesses include fever and malaria, diarrhea, respiratory infections and malnutrition as populations lose access to health services and become more insecure (Coghlan, 2006).

Relief Web ( maintains a list of complex emergencies, which currently includes 32 situations worldwide. These range from global food crises to political instabilities in Haiti and Zimbabwe to the situation in the Balkans (UN, 2008).

SWS and disease outbreaks
The SWS was initially developed in response to research linking the spread of cholera in South America in the early 1990s to unsafe storage of water at household level (Swerdlow, 1992). SWS programs have been used for cholera response ever since the first national scale programs were established in the late 1990s.

Two regional NGO affiliates in Zambia and Madagascar each launched SWS programs immediately before or during large cholera outbreaks and initial product sales were spurred by these epidemics (POUZN, 2007). A project evaluation in 2000 in Madagascar found that product demand created by the cholera epidemic and three subsequent cyclones stimulated both the rapid growth of a national scale project and confirmed use of the SWS in stored household drinking water (Dunston, 2001).

An investigation of the 2001 cholera outbreak in Fort Dauphin, Madagascar, suggested that use of the local sodium hypochlorite solution reduced the risk of illness (Reller, 2001). Locally produced sodium hypochlorite product is currently available in 19 countries, with the NGO ensuring quality, supply and distribution, which allows partner organizations to focus on emergency response.

In 2007, the same NGO worked with local and international organizations in 12 countries to distribute over 2.3 million bottles of sodium hypochlorite solution, treating 2.3 billion liters (607 million gallons) of water for cholera response. In Kenya, a program coordinated by CDC responds to cholera epidemics with technical assistance from trained staff, pre-prepared local language educational materials and the locally available NGO dilute chlorine water purification kit. In addition, nurses in a diarrheal disease surveillance program recommend this kit for use by patients presenting cholera or other diarrheal diseases at clinics.

The success of SWS programs in responding to cholera has been due to the local availability of product and the willingness of users to change behavior during cholera outbreaks. The challenge in these programs has been to translate SWS use during outbreak situations into long-term, consistent behavior change.

SWS response in natural disasters
In the spring of 2000, Cyclone Hudah struck the north coast of Madagascar and CARE, CDC and the regional NGO responded by providing 11,700 relief kits consisting of bottles of sodium hypochlorite solution and foldable jerry cans. An evaluation conducted five months after the emergency confirmed, through the presence of chlorine residual in household drinking water at the time of an unannounced visit, that 33 percent of people were using the sodium hypochlorite solution (Mong, 2001). In addition, users were willing to pay a median price of $0.38 (USD) for additional bottles of hypochlorite in the post-emergency phase.

These data highlighted the fact that SWS emergency response programs could successfully bridge from subsidized relief into sustainable recovery programs. The ongoing NGO Myanmar response to Cyclone Nargis highlights the importance of having established local production and program support prior to the emergency.

An NGO water purification program launched and operational in 2004 produced sodium hypochlorite solution locally when the cyclone hit, the operation was immediately able to rapidly increase production. As of July 11, 2008, 2,700 20-liter bulk jerry cans of sodium hypochlorite solution were distributed to organizations responding to the emergency, and 80,715 250-mL bottles. This is enough solution to treat 190 million liters (50 million gallons) of water.

Not all disaster response with the SWS has been as successful as the programs highlight above, however. The use of the SWS in response to the earthquake and tsunami in 2004 in Indonesia had mixed results.

Although the SWS product was available in Indonesia through CARE Indonesia prior to the tsunami, one report indicated that the SWS and other HWTS options were not widely used in the initial stages of the tsunami response. This was because many responders believed that water quantity was more of a concern than water quality, that the supply of bulk treated water in tankers was more appropriate and that resources were not available to launch new HWTS programs in the aftermath of the emergency. It was also believed that the introduction of new methods of water treatment during the acute emergency stage would send mixed messages and promote products that, ultimately, might not be sustainable (Clasen, 2005).

In contrast, CARE Indonesia distributed the SWS solution to tsunami-affected populations in communities they were already working within and an evaluation found that three to 14 percent of people in three intervention locations were using the product four months after the emergency. Chlorination of drinking water was found to be protective against contamination by Escherichia coli, while reported boiling (the traditional treatment method) was not (Gupta, 2007). These conflicting findings call into question the appropriateness of the SWS and HWTS in general in some emergency situations. Responders and implementers should take care to assess the situation prior to responding with a SWS intervention.

SWS programs in complex emergencies
The political, social and economic environment in Haiti has led to a designation of the entire country as in a state of complex emergency (UN, 2008). Despite this designation, there are successful and growing SWS programs in Haiti. One example is the Jolivert Safe Water for Families (JSWF) Program in rural, northern Haiti, which began in September 2002.

Sodium hypochlorite is produced locally at the Jolivert Clinic using a hypochlorite generator. Families purchase this disinfectant in refillable 250 ml bottles either at the clinic ($0.16 USD per bottle) or from 25 designated resellers throughout the surrounding towns and communities $0.20 USD per bottle, with the margin going to the reseller).

Three Haitian technicians produce the hypochlorite solution, offer training to bring new families into the program, conduct household visits to provide ongoing training and chlorine residual testing, sell the hypochlorite solution and maintain records. All program staff are fully paid from program income. Based on a successful pilot project evaluation documented over 40% diarrheal disease reduction in pilot users (Brin, 2003), the program began expanding from the initial 200 families and now has over 4,000 families enrolled. The program sells about 1,000 bottles of solution, treating one million liters of water, each month. The Jolivert program has been able to operate continuously and expand in a complex emergency environment and respond to numerous emergencies – including floods, hurricanes, political upheaval and riots. This is because of local production and management of the program, focus on training and one-to-one community-based follow-up with the users, as well as a steady, sustainable growth plan.

Safe water solutions
The safe water system is a proven, low-cost intervention that provides safe drinking water to people in developing countries and significantly reduces morbidity due to waterborne diseases. Although the majority of SWS program experience over the past decade has focused on providing cost-effective, sustainable access to safe drinking water within the development context, the SWS has also been used extensively in emergency response.

Successful SWS implementation programs provide both sustainable access to water treatment in the development context and a useful resource for preparedness and emergency response. And the effort can move between the two roles as the situation in the country changes and develops.


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About the author
Daniele Lantagne, P.E. is an Environmental Engineer working at the Centers for Disease Control and Prevention (CDC) Enteric Disease Epidemiology Branch in Atlanta, GA. Lantagne earned a bachelor’s degree and master’s degree in Environmental Engineering at MIT, and is pursuing her PhD at the London School of Hygiene and Tropical Medicine (LSHTM). She previously worked for five years at the Ipswich River Watershed Association and taught at the Edgerton Center at MIT, and later began working in household water treatment in developing countries during her master’s degree pursuit. During this period, she also continued to teach in the Department of Civil and Environmental Engineering at MIT, and also served as a private consultant. Lantagne has worked to implement and study chlorination, filtration and combined treatment household water treatment implementations in over 30 countries. She can be reached by phone at 404-639-0231, and by e-mail at [email protected].


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