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HWTS

Author/Compiled by
Bipin Dangol (Environment and Public Health Organization, ENPHO)
Dorothee Spuhler (seecon international gmbh)
Executive Summary

Lack of improved access to safe drinking water together inadequate sanitation and hygiene are the overwhelming contributors to the 1.8 million annual deaths caused by diarrhoeal diseases. Providing access to safe drinking water through centralised systems in developing countries is very challenging. Large distribution systems involve a lot of operation and maintenance and often, drinking water gets contaminated during distribution and during handling in the household. Hence, treating drinking water at household level by using simple, yet effective Household Water Treatment and Safe Storage (HWTS) options such as boiling, filtration, chlorination and SODIS could significantly reduce incidences of waterborne diseases.

Advantages
Relatively inexpensive and cost effective
Independent from an institutional set-up or centralised systems
Can be deployed faster than community/centralised drinking water treatment and supply systems
Improves microbial water quality and reduces contamination risk between treatment and use
Wide range of simple, low cost technologies are available so people can choos the technologies most appropriate for them
Disadvantages
Difficult to monitor correct operation and maintenance (O&M) of technologies
High self-responsibility required from the households
Each households should be provided with knowledge on O&M of the system
Treated water may be lower quality than that offered by a well designed, operated and maintained community system
In Out

Freshwater

Drinking Water

Background

Over one billion people still lack access to safe drinking water today. Waterborne diseases caused by consumption of unsafe drinking water are a major health burden in most of the developing countries in the world. Lack of safe water perpetuates poverty. Safe drinking water and sanitation are the condition for physical health and intellectual, social and economical activity and development.
The quality of drinking water being supplied is often neglected even if the access to water supply has been increased substantially. However, drinking water supplied by centralised treatment systems is likely to get contaminated due to poor distribution networks, management and unhygienic handling prior to consumption.
To treat the water at household level in order to assure the microbial (and chemical) quality together with safe water storage and proper hygiene practices could considerably contribute to reach the millennium development goals. Household-level Water Treatment and Safe Storage (HWTS) can reduce episodes of diarrhoeal diseases by 39% (WHO 2007a). According to the WHO (WHO 2007b) HWTS dramatically improves microbial water quality; significantly reduces diarrhoea; is among the most effective of water, sanitation and health interventions; is highly cost-effective; and can be rapidly deployed and taken up by vulnerable populations.

Steps of HWTS

HWTS is a multi-barrier approach and there are several steps in HWTS which all contribute (adapted from CAWST 2009):

 The five steps of the multi-barrier approach of HWTS.

The five steps of the multi-barrier approach of HWTS. Source:  CAWST (2009) 

Using the multi-barrier approach is the best way to reduce the risk of drinking unsafe water. We need to follow a process and not just rely on a single technology to improve water quality. Both community and household water treatment systems follow the same water treatment process. The only difference is the scale of the systems that are used by communities and households.

The multi-barrier approach of HWTS contributes to stop microbial pollution and thus reduces the health risks linked to waterborne disease (CAWST 2008)

The multi-barrier approach of HWTS contributes to stop microbial pollution and thus reduces the health risks linked to waterborne disease. Source: (CAWST 2008)

Source Protection

Risks, which may threaten drinking water quality at the source or point of collection include: poor site selection or protection; poor construction and deterioration or damage to structures; and lack of hygiene and sanitation knowledge in the community. Actions that can be taken at the community level to eliminate these risks can include: regularly cleaning the area around the water source; moving latrines away from and downstream of water sources; building fences to prevent animals from getting into open water sources; lining wells to prevent surface water from contaminating the ground water; building proper drainage for wastewater around taps and wells.

Sedimentation

Settling alone can remove large amount of turbidity. Source: CAWST

Settling alone can remove large amount of turbidity. Source: CAWST (2007)

Sedimentation is a physical treatment process used to reduce the turbidity of the water (see also sedimentation). Suspended materials in water, such as particles of sand, clay, and other materials can be substantially removed simply by settling the water. This can be done by using a natural reservoir, a settling pond, or a large tank. The sedimentation process can be accelerated through the use of coagulants and flocculants. These are natural (e.g. Moringa) and synthetic (e.g. purifier of water, PUR) chemicals that change the electrical charges of the suspended materials. This allows the particles to join together, thereby increasing their mass so that they settle to the bottom of the container. Since bacteria and viruses are often attached to particle surfaces, the removal of particles through sedimentation will produce a marked reduction in bacterial concentrations.

Filtration

Filtration is commonly used after sedimentation to further reduce turbidity and remove pathogens. Filtration is a physical process which involves passing water through filter media. Filters remove pathogens in several ways. These include straining, where the particles or larger pathogens such as worms become trapped in the small spaces between the grains of filter media; adsorption, where pathogens become attached to the filter media; or biological processes, where pathogens die naturally or the microorganisms living in the filter consume the pathogens.

There are various types of filters that are used by households around the world including ceramic candle filterscolloidal silver filters, biosand filters, cloth straining, biosand filters adapted for arsenic removal, membrane filters (e.g. lifestraw), etc.. Sand and ceramic are the most common filter media, although cloth filters are also often used. 

Disinfection and Pasteurisation

The destruction of the organisms’ cell walls by oxidation is known as disinfection. Typically, disinfection involves the addition of chemicals such as chlorine. It can also be induced by ultraviolet radiation, such as natural sunlight or artificial UV rays.
The most common methods used by households around the world to disinfect their drinking water is chlorination.

Heat can also kill microorganisms and this process is called pasteurisation. Pasteurisation has almost the same effect as disinfection. The most common methods to pasteurise water are boiling, solar disinfection or solar pasteurisation.

If water contains high amounts of organic matter (for instance surface water from tropical regions), there is a risk of the formation of toxic disinfection products when chlorine reacts with these organics. Turbid water helps pathogens to “hide” from chemicals and natural or artificial UV radiation. Reducing turbidity and organic matter by sedimentation and filtration before the treatment  is therefore necessary to improve the effectiveness of these disinfection methods.

Safe Storage

Containers for safe storage of treated water Source: CAWST (2009)

Containers for safe storage of treated water Source: CAWST (2009)

Households do a lot of work to collect, transport and treat their drinking water. Now that the water is safe to drink, it should be handled and stored properly to keep it safe. If it is not stored safely, the treated water quality could become worse than the source water and may cause people to get sick.
Safe storage means keeping treated water away from sources of contamination, and using a clean and covered container. It also means drinking water from the container in a way so that people do not make each other sick. The container should prevent hands, cups and dippers from touching the water, so that the water does not get re-contaminated.
There are many designs for water containers around the world. A safe water storage container should have the following qualities:

  • Strong and tightly fitting lid or cover
  • Tap or narrow opening
  • Stable base so it does not tip over
  • Durable and strong
  • Should not be transparent (see-through)
  • Easy to clean

Regarding the safe storage of water, disinfection with chlorine has a advantage over the other methods, as chlorine has a residual effect.

Applicability

Household Water Treatment and Safe Storage (HWTS) is particularly suitable in places where people are using contaminated drinking water sources and relying on potentially contaminated centralised water supply systems. HWTS is also suitable for urban poor communities such as slums where households are very likely to use unprotected water sources.

Library references

Combating Waterborne Diseases at the Household Level

This document is divided into three main parts. The first part contains an introduction to the topic and depicts some possible, simple techniques for treating water at the household level. The second part describes the possibility of collaborating to fight against waterborne diseases and the last part presents again some low-cost solutions.

WHO (2007): The International Network to Promote Household Water Treatment and Safe Storage. Geneva: World Health Organisation (WHO) URL [Accessed: 11.10.2010]

Water Hygiene Sanitation Poster Presentation

Water, Hygiene and Sanitation Posters - The presentation includes 30 posters with key messages and questions on water, hygiene and sanitation. They are adapted for different regions including: Africa, Latin America, South Asia, Southeast Asia; and are available in multiple languages.

CAWST (2008): Alberta: Center for Affordable Water and Sanitation Technology (CAWST) URL [Accessed: 18.02.2011]
Further Readings

Household water treatment 1. Well Factsheet

This Technical Brief is the first of two examining the treatment of water in the home. The subject is introduced, and treatment by straining, storage, settlement, solar disinfection, chemical disinfection, and boiling are covered.

SKINNER, B. ; SHAW, R. ; (1999): London & Loughborough: Water And Environmental Health at London and Loughborough (Well) URL [Accessed: 05.05.2010]

Household water treatment 2

This Technical Brief is the second of two which examine the treatment of water at household level. It considers treatment by coagulation, flocculation, filtration and solar distillation and covers aspects of the reduction of some chemical concentrations.

SKINNER, B. ; SHAW, R. ; (1999): (= Well Factsheet , 59 ). London & Loughborough: Water And Environmental Health at London and Loughborough (Well) URL [Accessed: 05.05.2010]

Combating Waterborne Diseases at the Household Level

This document is divided into three main parts. The first part contains an introduction to the topic and depicts some possible, simple techniques for treating water at the household level. The second part describes the possibility of collaborating to fight against waterborne diseases and the last part presents again some low-cost solutions.

WHO (2007): The International Network to Promote Household Water Treatment and Safe Storage. Geneva: World Health Organisation (WHO) URL [Accessed: 11.10.2010]

Scaling Up Household Water Treatment Among Low-Income Populations

This report examines the evidence to date regarding the scalability of HWTS. It seeks to consolidate existing knowledge and experience and distil the lessons learnt. Its primary aims are to 1) review the development and evolution of leading household water treatment technologies in their efforts to achieve scale, 2) identify the main constraints that they have encountered and 3) recommend ways forward.

CLASEN, T.D. ; (2009): (PhD Thesis). Geneva: World Health Organization (WHO) URL [Accessed: 09.04.2010]

Household Water Treatment and Safe Storage Options in Developing Countries. Review of Current Implementation Practices

Summary and brief evaluation of main household water treatment and safe storage (HWTS) options for developing countries. Options described are: chlorination, biosand filtration, ceramic filtration, solar disinfection, filtration and chlorination, flocculation and chlorination.

LANTAGNE, D. S. ; QUICK, R. ; MINTZ, E.D. ; (2006): ECSP (2006): Water Stories: Expanding Opportunities in small-scale Water and Sanitation Projects. Washington D.C.: ,17-38 . URL [Accessed: 06.04.2010]

Implementation, Critical Factors and Challenges to Scale-Up of Household Drinking Water Treatment and Safe Storage Systems

This paper explores the current status of the adoption and sustained use of household drinking water treatment and safe storage systems, the critical factors that influence adoption and sustained use and the associated challenges to scale-up.

MURCOTT, S. ; (2006): Background Paper on Household Water Treatment and Safe Storage (HWTS) for the Electronic Conference . USAID / Hygiene Improvement Project (HIP) URL [Accessed: 26.02.2010]

Smart Disinfection Solutions

This booklet, part of the Smart Water Solutions series provides a wide range of methods and products for home water treatment in rural areas.

NWP (2010): Examples of small-scale disinfection products for safe drinking water. (= Smart water solutions ). Amsterdam: KIT Publishers URL [Accessed: 07.07.2010]

Household Water Treatment and Storage (HWTS) Guidelines

PATH has created guidelines (only online available) for designing and developing household devices for treating unsafe water and safely storing it for use. The guidelines provide evidence-based criteria for effective, commercially viable products that meet or exceed user expectations for long-term use. They take into account the unique needs of users in the developing world. These guidelines will help to advance development and use of household water treatment and storage (HWTS) devices by providing benchmarks for product attributes and performance.

PATH (2011): Seattle: PATH - Safe Water Team URL [Accessed: 20.12.2011]

Small Community Water Supplies: Technology, People and Partnership: Desalination Technology - Chapter 18

This book provides a general introduction to a wide range of technologies. Among the topics covered are: planning and management of small water supplies, community water supplies in Central and Eastern European countries, water quality and quantity, integrated water resources management, artificial recharge, rainwater harvesting, spring water tapping, groundwater withdrawal, water lifting, surface water intake, water treatment, aeration, coagulation and flocculation, sedimentation, multi-stage filtration, desalination technology, disinfection, household level water treatment, technologies for arsenic and iron removal from ground water, and emergency and disaster water supply. Chapter 18: Desanilation Technology

SMET, J. ; WIJK, C. van (2002): The Hague: International Water and Sanitation Centre (IRC) URL [Accessed: 29.02.2012]

Drinking Water: Equity, Safety and Sustainability

The report investigates access to and use of drinking water in greater detail than is possible in the regular JMP progress reports, and includes increased disaggregation of water service levels and analyses of trends across countries and regions. It focuses on the three key challenges of equity, safety and sustainability.

UNICEF ; WHO (2011): New York and Geneva: United Nations Children's Fund (UNICEF) and World Health Organization (WHO) URL [Accessed: 05.03.2012]

Access and Behavioural Outcome Indicators for Water, Sanitation and Hygiene

This manual aims to help program planners, managers, and evaluators to design, implement, and evaluate WASH interventions. It is intended for use either in programmes and projects with a principal focus on WASH or with a broad child health agenda.

USAID (2010): New York: United States Agency for International Development (USAID), Hygiene Improvement Project URL [Accessed: 09.04.2010]

Guidelines for Drinking-water Quality, Fourth Edition

This volume of the Guidelines for Drinking-water Quality explains requirements to ensure drinking-water safety, including minimum procedures and specific guideline values, and how those requirements are intended to be used. The volume also describes the approaches used in deriving the guidelines, including guideline values. It includes fact sheets on significant microbial and chemical hazards.

WHO (2011): Geneva: World Health Organization (WHO) URL [Accessed: 08.08.2011]

Evaluating Household Water Treatment Options

Household water treatment (HWT) interventions may play an important role in protecting public health where existing water sources, including those delivered via a piped network or other improved sources, are untreated, are not treated properly or become contaminated during distribution or storage. Properly formulated and locally relevant performance specifications are needed to protect users and inform decision-making regarding selection of technologies or approaches. This document provides a basis by which to evaluate the microbiological performance of HWT options.

WHO (2011): Health-based Targets and Microbiological Performance Specifications. Geneva: World Health Organization (WHO) URL [Accessed: 17.10.2011]

Toolkit for monitoring and evaluating household water treatment and safe storage

In order to develop effective mechanisms to encourage and sustain correct use of household water treatment and safe storage (HWTS), there is a need to monitor and evaluate uptake. The Toolkit provides an overall framework for this. One of the key features is the presentation of 20 harmonized, global indicators to assess correct and consistent use of household water treatment and safe storage by those most at risk.

WHO ; UNICEF (2012): Geneva: World Health Organization URL [Accessed: 08.11.2012]

Conservation et Traitement de l Eau a Domicile

This practical guide provides a review of different processing techniques and adequate water conservation at home and is structured around 10 key questions that should be posed before choosing a suitable solution.

DESILLE, D. ; (2013): Paris: Programme Solidarite Eau (PSeau) URL [Accessed: 06.06.2013]

Combined Household Water Treatment and Indoor Air Pollution Projects in Urban Mambanda, Cameroon and Rural Nyanza, Kenya

Globally, the burden of ill‐health in Africa due to unsafe drinkingwater, inadequate sanitation and polluted indoor air stands out prominently. This report explores the possibilities, advantages and implications of integrating interventions on indoor pollution and household water treatment.

SHAHEED, A. ; BRUCE, N. ; (2011): (= Report of a Mission to Mambanda, Cameroon and Nyanza, Kenya, 2009 ). Geneva: World Health Organization (WHO) URL [Accessed: 09.12.2013]
Case Studies

Nudging to Use

This paper presents results from two complementary field experiments conducted in rural western Kenya and the urban slums of Dhaka, Bangladesh. In both settings, participating households received free trials with a variety of point of use products as well as repeated educational messages about the importance of safe drinking water and its link with diarrheal illness.

LUOTO, J. ; LEVINE, D. ; ALBERT, J. ; LUBY, S. ; (2013): Achieving Safe Water Behaviors in Kenya and Bangladesh. Berkeley: Center for Effective Global Action URL [Accessed: 07.08.2013]
Training Material

UNICEF Handbook on Water Quality

This handbook is a comprehensive a new tool to help UNICEF WASH field professionals, but it will also be useful to other UNICEF staff and for partners in government, other external support agencies, NGOs and civil society. The handbook provides an introduction to all aspects of water quality, with a particular focus on the areas most relevant to professionals working in developing countries. It covers the effects of poor water quality, quality monitoring, the protection of water supplies, methods for improving water quality, and building awareness and capacity related to water quality.

UNICEF (2008): New York: United Nations Children's Fund (UNICEF) URL [Accessed: 30.03.2010]

Course Outline for Introduction to HWTS workshop

This document provides the course outline to conduct two to three-days training for an introduction to HWTS.

CAWST (2009): Alberta: Center for Affordable Water and Sanitation Technology (CAWST) URL [Accessed: 27.03.2010]

Household Water Treatment and Safe Storage (HWTS). Lecture Notes

Lecture notes on the technical and non-technical aspects of sanitation household-level drinking water treatment and safe storage (HWTS) in developing countries.

EAWAG/SANDEC (2008): (= Sandec Training Tool 1.0, Module 3 ). Duebendorf: Swiss Federal Institute of Aquatic Science (EAWAG), Department of Water and Sanitation in Developing Countries (SANDEC) URL [Accessed: 08.04.2010]

Amoeba and Water

This children’s book provides information on safe drinking water, ways of water contamination, simple HWTS options presented in attractive illustrations and simple languages so that school children can easily understand them.

ENPHO (2007): Kathmandu and New York: Environment and Public Health Organization (ENPHO) and United Nations Children's Fund (UNICEF) URL [Accessed: 09.04.2010]

Household water treatment and safe storage in emergencies

This document is intended as a general manual on household water treatment and storage in emergencies. Methods of treatment but also promotion are presented, including factsheets, a decision tree and very comprehensive illustrations.

IFRC (2008): pdf presentation. Geneva: International Federation of Red Cross and Red Crescent Societies (IFRC) URL [Accessed: 23.04.2012]

Flip Chart on HWTS

Flipchart presentation on description of different household water treatment options including introduction, installation and organisation and maintenance procedures of each technology (in Nepali).

DWSS (2007): Nepal: Department of Water Supply and Sewerage (DWSS)

HWTS training guideline

This training manual provides information on various household drinking water treatment options. Each description contains an introduction to the technology, its working mechanism, costs, advantages and limitations (Nepali).

DWSS (2008): Nepal: Department of Water Supply and Sewerage (DWSS)

Water Hygiene Sanitation Poster Presentation

Water, Hygiene and Sanitation Posters - The presentation includes 30 posters with key messages and questions on water, hygiene and sanitation. They are adapted for different regions including: Africa, Latin America, South Asia, Southeast Asia; and are available in multiple languages.

CAWST (2008): Alberta: Center for Affordable Water and Sanitation Technology (CAWST) URL [Accessed: 18.02.2011]
Awareness Raising Material

Combating Waterborne Diseases at the Household Level

This document is divided into three main parts. The first part contains an introduction to the topic and depicts some possible, simple techniques for treating water at the household level. The second part describes the possibility of collaborating to fight against waterborne diseases and the last part presents again some low-cost solutions.

WHO (2007): The International Network to Promote Household Water Treatment and Safe Storage. Geneva: World Health Organisation (WHO) URL [Accessed: 11.10.2010]

HWTS factsheets

Compilation of factsheets on water quality in general and description of different HWTS options such as chlorination, colloidal silver filters, biosand filter, chlorination and SODIS.

DWSS (2007): Department of Water Supply and Sewerage (DWSS) Nepal, United States Agency for International Development (USAID), United Nations Human Settlements Programme (UN-HABITAT), United Nations Children's Fund (UNICEF)

HWTS Brochure (Nepali)

Brochure on HWTS options in general (Nepali).

DWSS (2007): Nepal: Department of Water Supply and Sewerage (DWSS)

HWTS Posters (Nepali)

Posters on HWTS options in general such as colloidal silver filter, biosand filter, chlorination and SODIS with general descriptions, advantages and limitations of each technology (Nepali).

DWSS (2007): Nepal: Department of Water Supply and Sewerage (DWSS)

HWTS Comic Posters (Nepali)

Comic posters on HWTS options in general with general descriptions, advantages and limitations of each technology (Nepali)

DWSS (2007): Nepal : Department of Water Supply and Sewerage (DWSS)

HWTS Materials Users Guide

This user’s guide provides information on the use of various HWTS materials including targeted audience of each material. (Nepali)

DWSS (2007): Nepal: Department of Water Supply and Sewerage (DWSS)

Language: Norwegian

Alternative Versions to

No Structure Described.