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Saturday, May 16, 2009

Environmental Health

House Water Treatment and Storage has gained prominence in recent years as an interim solution to improving access to safe water.

Dr Chukwuemeka Nwaneri
Centre for Global Health
Trinity College
University of Dublin
Ireland

Table of content
Introduction
Overview of Household water treatment and storage
Household water treatment strategies
· Chlorination
· Filtration
· Boiling by thermal technology
· Solar disinfection method
· Flocculation and Coagulation disinfection combination method
Household water storage strategies
The effectiveness of various HWTS (including cost-effectiveness) technologies
The challenges of scaling up some of the main options promoted
Conclusion
References

Introduction
The consequences of natural disasters, environmental health issues including drought and flooding, with resultant outbreaks of infection diseases such as cryptosporidium, cholera do weigh adversely to the limited healthcare facilities, hence deplete the economic and human resources available in such countries.
The versatility and feasibility of utilization of household water and storage makes it a useful intervention tool in addressing such waterborne diseases and emergencies as an interim solution. It has been emphasized that HWTS is not solely for situations of emergencies or outbreaks of diseases but also can be used in the prevention of contamination of home stored water (UNICEF, 2008), from unsafe wells or piped water sources (WHO, 2009).
Overview of Household Water Treatment and Storage
Household Water Treatment and Storage implies the systems and methodologies of achieving potable and clean water devoid of potential harmful disease causing pathogens and other water-borne diseases at the point of use. The purpose is to improve the water microbial quality and reduce the burden families’ face in accessing safe water sources for consumption (Sobsey, 2002).
It is documented in WHO Report of 2008 titled: “Managing water in the home: accelerated health gains from improved water supply” that regardless of whether the source of water is contaminated or not, transporting and storing provides a source of contamination following unhygienic collection, handling and storage practices and behaviours. Therefore there is need to device a means of improving and maintaining the microbial water quality which should be feasible, accessible, and sustainable and for dissemination in the local population based on requirements (Sobsey, 2002; 2008).
Household water treatment and storage can be uncomplicated, effective, cheap and attainable in terms of value for money. The advantages of household water treatment cannot be over-emphasized; it ranges from drastic reduction in worldwide incidence and burden of diarrheal diseases (between thirty to forty percent), to the contribution of the achievements of Millennium Development Goals (Schmidt & Cairncross, 2009).
According to the WHO (2005) report, about 1.5 million deaths result from the consumption of unsafe drinking water, sanitation and hygiene issues, majority been children below the ages of 5. Unclean water serves as reservoir from hepatitis B, typhoid, leptospirosis and other pathogens especially in vulnerable persons such as those with HIV/AIDS and other immunodeficiency states (UNICEF, 2008).
The recent figure by WHO/UNICEF in 2006 is frightening as an approximate 1.1 billion people mostly living in the developing world are without potable water (UNICEF, 2008).
According to literature, Conroy (2001), Doocy (2006), and UNICEF (2008), identifies various methods including solar, chlorination at point of use combination of disinfection and flocculation methods, boiling, which have been demonstrated to be valuable in the prevention of waterborne diseases in fragile states and epidemic circumstances.

Household Water treatment Strategies
The principle behind household water treatment and storage is derived from the general water treatment which occurs in four stages; coagulation and flocculation; sedimentation; filtration and disinfection. The various technologies utilize one or a combination of the stages at a household level.
There are various types of water treatment options available throughout the world. They range from chemical disinfection, solar disinfection, filtration, ultraviolet radiation disinfection through sunlight, combined flocculation-chlorination methods to boiling and safe storage, depending on the availability, acceptability and applicability in the community setting and population, although of varying efficacies and effectiveness’s.
It is suggested that households, should continue treating their water especially in emergency situations until appropriate tested and safe water is supplied, and for stable population without potable water, appropriate water treatment and storage intervention should continue to reducing microbial quantity, preventing waterborne infections UNICEF, 2008).
The following are the types of treatment modalities available to improve the microbial quality of household water:
I. Chemical technologies
a) Coagulation-flocculation combination
b) Ion exchange
c) Chemical disinfection (chlorine tablets or sachets)
d) Precipitation
e) Adsorption
II. Physical technologies
a) Boiling
b) Heating (using sunlight in the form of solar and fuel)
c) Filtration
d) Ultraviolet light radiation disinfection (sunlight and lamps)
e) Sedimentation

Chemical disinfection-Chlorination method
Globally, chlorination in various forms have wide acceptance, and probably the most practiced method of water treatment at household and community levels next to boiling method. Chlorine can come from household bleach (hypochlorite), sachets, tablets, and lime. Bleaching powder, stabilized/tropical sources, high-test hypochlorite are other sources of chlorine, with varying percentages of chlorine. They are easily available, accessible, simple, practical, cheap and easy to use (UNICEF, 2008). Some of the disadvantages of chlorination are in the taste and odour of the water and possibility of excessive chlorination of the water as well as its inability to remove turbidity form water.

Filtration method
Filtration can be in the form of ceramic filters, slow sand filters or ‘Biosand’ filters. In settings where filters are easily affordable it can serve as an alternative to water purification measure. It poses an advantage of retaining the aesthetic properties of water without introducing taste or odour problems. Another advantage is in the accessibility and been inexpensive (UNICEF, 2008). The disadvantages include the fact that training and education is needed in areas of fabrication and maintenance. Ceramic filters can be produced in commercial quantities in the rural communities with the expertise and if properly maintained can be very durable and long lasting (WHO, 2002).

Boiling by thermal technology
The reliability of boiling as a method of disinfection of household water is not in doubt as this is evidenced by the WHO GDWQ recommendation which suggest bringing water to a rolling boil for about 5 minutes which assures that an adequate high enough temperature has been attained to result in extermination of enteric pathogens and others organisms including viruses and ova of worms. The only draw back is in the cost and time consumption and utilization in the purchase of kerosene, gas or firewood as well as the issues of indoor pollution and consequent respiratory tract infections (UNICEF, 2008). It also has the problem of not been able to remove the turbidity of water.

Solar disinfection method
Ultraviolet light disinfection combines heat and UV light radiation in the disinfection of household water. According to Hobbin (2004) and UNICEF Report (2008) UV light disinfection has been demonstrated to eliminate microbial organisms hence increases the quality of household water and therefore reducing the diarrhoeal prevalence associated with contaminated water sources. The most popular of the solar technologies is the SODIS system which was introduced by the Swiss Federal Institute for Environmental Sciences and Technology. The advantage is that it is easy to practice, accessible, economical and available to many settings and communities. The only disadvantages are that bottles are used in the storage process and issues around its inability to remove the turbidity of water and re-contamination after disinfection if not properly stored.

Flocculation and Coagulation disinfection combination method
In communities with water of high turbidity, other modalities can be disadvantaged in the reducing physical turbidity of the household water even after disinfection has been completed. Flocculation and coagulation combination reduces turbidity by the use of Alum (aluminium sulphate) which brings suspended particles together and settles out during sedimentation. Alum is inexpensive, accessible, and affordable, as well as effective (WHO, 2007). It can be used to augment physical sedimentation or on its own reduce the turbidity and reduce the protozoan load which chemical technologies rarely remove. According to the report by UNICEF, flocculation and disinfection unlike any other technology reduces the arsenic levels in household water in vulnerable settings (UNICEF, 2008).
Amongst the listed methodologies, only chlorination and storage in safe containers and ultraviolet light disinfection have been widely studied to reduce the microbial contamination hence reducing the potential diarrhoeal and other water borne infectious properties. Sobsey stated that apart from the more complex, inaccessible treatment technologies, the majority of the methods prove to be cheap, simple and easy to use as well as accessible to the populace in both emergencies and epidemic settings (Sobsey, 2002).
In respect to the improvement of the microbiological quality of the household water, boiling, solar in combination of heat and or UV radiation (sunlight or lamps); chlorination of stored water in appropriate vessels and chlorination and chemical coagulation and filtration combination have been proven to be promising in terms of dissemination, development and implementation. Regardless, each method poses unique strengths and weaknesses (Sobsey, 2002).

Household Water Storage Strategies
Different researchers have reported various strategies of water storage being contributory to the decreased microbial quality level (WHO, 2007). Examples of storage vessels which increases the risk of waterborne infections from inadequate storage following increased vulnerability of the containers or vessels to contamination by faecal pathogens include, water jars, capped plastic vessels, metal jars, clay jars in homes, elevated tanks at home and public places, plastic vessels, drums, barrels and buckets (Miller, 1984). Other factors have also been identified by Black et al (1983) and Iroegbu et al (2000) as been responsible for possible bacterial contamination of the stored water at home, these include tropical whether and elevated temperatures prolonged duration of storage, unhygienic practices and poor hand washing techniques, high dust particulates and the utilization of contaminated stored water in preparing fresh meals that are not properly cooked, use in child and infant food preparation.
It is reported in literature (WHO, 2007) that containers with taps or spigots tend to protect against contamination and reduce the likelihood of microbial quality from poor handling during storage. For safe storage of water, different vessel designs have been advocated such as light weights with dispensing devices, solar-radiation friendly containers.

The effectiveness of various HWTS (including cost-effectiveness) technologies
In terms of household water treatment and storage cost-effectiveness is the measure of cost of household water treatment and storage, and its effectiveness in identified health outcome such as diarrhoeal diseases. The WHO guidelines for Drinking water Quality (GDWQ) aim to identify the major health-associated quality constituents of water and match it with the standards as measured by Hazard Analysis-Critical Control Points (HACCP) management tool. For the safety of the vulnerable population there is need for continual monitoring and evaluation of the effectiveness of household water treatment and storage systems (Sobsey, 2002).
The efficiency of chlorination in exterminating enteric pathogens is about 99.9%, though cryptosporidium and mycobacterium are spared (Arnold, 2006).
Filtration has been practiced from the ancient time, but there have been modifications to the traditional practice. Hijnen (2004) reported that when slow sand filters are properly designed and operated its efficiency is about 99% or more in removing enteric pathogens. Some of the filters are pre-treated with microbicidal silver which enhances its efficiency to nearly 100%.
Whether by direct heat or solar heating, boiling household water has been documented to be effective against a wide spectrum of faecal coliforms. It is evidenced that boiling household water is effective in the destruction of a wide range of organisms including bacteria, ova of worms, protozoan, viruses, spores and non-spore pathogens and fungi. Boiling has an advantage of eliminating other organisms’ chlorination spares such as cryptosporidium, and Entamoeba and Giardia species (Sobsey & Leland, 2001). The effectiveness of boiling as a method of disinfection of household water treatment is often questionable if water is stored in a different container than one used in the boiling as there is potential re-contamination, or if stored for a prolonged time before usage and also at high altitude (WHO, 2002).
Combination of flocculation and coagulation disinfection therefore provides about 99.9% reduction in waterborne cysts, viruses and enteric bacteria (Souter, 2003).
The utilization of solar forms of disinfection has been proved to be effective as documented in the studies of Acra et al (1984) which pioneered the research into the most effective approach of UV light disinfection of household water. The efficiency and effectiveness of UV light disinfection is more marked if the bottle is black in colour which enhances the absorption of heat (Joyce et al, 1996; Sobsey, 2002). The SODIS system achieves effectiveness up to 99.9% in the destruction of faecal viruses, bacteria and fungi. The type of container, the structural material in the design of the container, the capacity affects water temperature and heating and ultraviolet radiation penetration hence microbial quality. Also the exposure of the containers to full sun lights without shades, duration of exposure (usually acceptable duration id 6-8 hours) influences water temperature and ultraviolet penetration (Sobsey, 2002).
Household water treatment and storage has been demonstrated to be cost-effective method of preventing diarrhoeal diseases resulting from water sources in resource poor and fragile states. The implication of promoting HWT and storage helps provide water security to these groups (UNICEF, 2008), and improve water microbial quality (WHO, 2002).
Clasen et al (2007) reported that household water treatment was cost-effective when benchmarked against international standards especially with chlorination at resource poor setting and filtration at household level where resources were better off and consequent improvement in health gains. Their research highlighted the importance of local conditions, cost recovery potentials and user preference in the selection and acceptability of the particular household water intervention (Clasen et al, 2007).
Table shows the cost-effective ratios (adapted from Clasen, 2008)
Sub-region
Intervention
Cost per DALY averted in US $
Cost-effectiveness
(CMH Benchmark)
Afr-E
Source
Household Chlorination
Household Filtration
House Solar disinfection
Household flocculation disinfection
123(14-322)
53(41-447)
142(83-223)
61(38-104)
472(70-813)
Highly cost-effective
Highly cost-effective
Highly cost-effective
Highly cost-effective
Cost effective (highly cost-effective at net cost of US $354)

The challenges of scaling up some of the main options promoted
Schmidt and Cairncross (2009) reported reviewing the evidence of non-health benefits, acceptability, adverse effects and scalability as a determinants in establishing the possibility of global acceptable of scaling up of household water treatment and storage.
Clasen (2008) identifies that in communities where household water and storage is to be scaled up, there exists special challenges which include the belief that diarrhoea is not a disease; doubts about the effectiveness of the particular intervention strategies; technical shortcoming and evidence of inequality and utilization.
For scaling-up of these technologies especially chlorine based products such as tablets, household filters and solar disinfections, concerted efforts geared at procuring more funds from donors, commercial structures, community collaboration and participation with stakeholders such as Ministry of Health, Water and Environment, should be encouraged (WHO, 2001).
For the effective outcome and utilization even in the state of availability and accessibility, community mobilization and participation, acceptance and effective social marketing is important (Schmidt & Cairncross, 2009). WHO documents that about five million households in about seventeen countries mostly in developing parts of the world have benefited from household water treatment and storage interventions through a combination of social marketing, public and commercial mobilization (WHO, 2001).
Clasen (2008b) in his study identified hindering challenges in the scaling up of HWTS. These challenges include the need to engage the participating communities and other stakeholders in a collaborative, participatory manner to increase acceptability and wider utilization and coverage. He also informed of the need for governmental role in educational campaign in the dissemination and awareness creation of the HWTS to encourage increasing demand (WHO Global WASH programme, 2001).
Effective and radical implementation of the HWTS utilization in the wider settings should be encouraged but there is the need to promote partnerships with private sector, social marketing agencies in the household water treatment scaling up programmes.
Conclusion
Household water treatment and storage has gained prominence in recent years as an interim solution to improving access to safe water. Various studies have shown that improving the microbial quality of the household water at point of use, using different modalities which is appropriate for the population and community setting, do reduce the diarrhoeal and other waterborne infections, of course a function of the efficiency, practicability and availability of the technology. There still remain challenges of scaling up some of the main options promoted, which includes issues of sustainability, affordability, acceptability and technical difficulties.
References
Acra, A., Raffoul, Z., & Karahagopian, Y. (1984). Solar Disinfection of Drinking and Oral rehydration Solutions-Guidelines for Household Application in Developing Countries. UNICEF, American University of Beirut. [Online]. Available at http://almashriq.hiof.no/lebanon/600/610/614/solar-water/unesco/. (Accessed: 8 March 2009).
Arnold, B. & Colford, J. (2007). Treating water with chlorine at point-of-use to improve water quality and reduce child diarrhoea in developing countries: a systematic review and meta-analysis. Am J Trop Med Hyg. Vol. 76. No. 2: pp 354-64.
Clasen, T. (2008). Scaling Up Household water Treatment: Looking Back, seeing forward. Geneva: World Health Organisation.
Clasen, T (2008b)> Household Water Treatment: effectiveness, cost-effectiveness and the challenge of scaling up. [Online]. Available at http://www.iom.edu/object:file/master/59/296/clasen.pdf. (Accessed: 8 March 2009).
Clasen, T. (2008). Developing a National Strategy for Scaling Up Household Water Treatment and Safe Storage in Lao PDR. [Online]. Available at http://www.wpro.who.int/NR/rdonlyres/594CFEBE-3C10-474A-8C4C-1098A1B043D4/0/MissionReport_DrClasenLaoPDRJune2008_.pdf .(Accessed 8 March 2009). Clasen. T., Haller, L., Walker, D., Bartram, J. & Cairncross, S. (2007). Cost-effectiveness of Water quality for preventing diarrhoeal disease in developing countries. Journal Water Health. Vol 5. No. 4: pp 599-608. [online]. Available at http://www.ncbi.nlm.nih.gov/pubmed/17878570. (Accessed: 8 March 2009).
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Doocy, S., & Burhnam, G. (2006). Point-of-use water treatment and diarrhoea reduction in the emergency context: an effectiveness trial in Liberia. Trop Med Int Helath. Vol 11. No. 10: pp 1542-1552.
Joyce, T.M., McGuigan, K.G., Elmore-Meegan, M. & Conroy, R.M. (1996). Inactivation of fecal bacteria in drinking water by solar heating. Applied & Environmental Microbiology. Vol. 62. No. 2: pp 399-402.
Schmidt, W. & Cairncross, S.(2009). Household water Treatment in Poor Population: is There Enough Evidence for Scaling up Now? Environmental Science Technology. Vol. 43. No. 4:pp 986-992. [Online]. Available at http://www.pubs.acs.org/doi/abs/10.1021/es802232w. (Accessed: 8 march 2009).
Sobsey, M.D. (2002). Managing water in the home: accelerated health gains from improved water supply. Geneva: the world Health Organisation (WHO/SDE/WSH/02.07).
Sobsey, M.D., & Leland, J.S.E. (2001). Antiprotozoan and Antihelminthic Agents. In: Disinfection, Sterilization, and Preservation. 5th Edition. S.S. Block (ed.). new York, Lippincott Williams & Wikins.
UNICEF. (2008). Promotion of Household water treatment and safe storage in UNICEF wash programmes. [Online]. Available at http://www.portal.worldwaterforum5.org/wwf5/en-us/lists/learning%20.pdf. (Accessed: 8 March 2009).
World Health Organisation. (2001). Household Water management at Global WASH Forum: Scaling up. [Online]. Available at http:www.who.int/household_water/advocacy/was_forum/en/. (Accessed: 8 March 2009).
World Health Organisation. (2002). Household Water Treatment and Safe Storage Following Emergencies and Disasters: South Asia Earthquake and Tsunami. [Online]. Available at http:// who.int/water_sanitation_health/hygiene/emergencies/em2002chap7.pdf. (Accessed: 8 March 2009).
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