Household Water Treatment and Safe
Storage Systems (HWTS)
Bipin Dangol, ENPHO
Dorothee Spuhler, seecon international gmbh
Household Water Treatment and Safe Storage Systems (HWTS)
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Disclaimer
The contents of the SSWM Toolbox reflect the opinions of the respective authors and not necessarily the official opinion of the funding or
supporting partner organisations.
Depending on the initial situations and respective local circumstances, there is no guarantee that single measures described in the toolbox
will make the local water and sanitation system more sustainable. The main aim of the SSWM Toolbox is to be a reference tool to provide
ideas for improving the local water and sanitation situation in a sustainable manner. Results depend largely on the respective situation
and the implementation and combination of the measures described. An in-depth analysis of respective advantages and disadvantages and
the suitability of the measure is necessary in every single case. We do not assume any responsibility for and make no warranty with
respect to the results that may be obtained from the use of the information provided.
Household Water Treatment and Safe Storage Systems (HWTS)
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Contents
1. Water Quality and Safe Drinking Water
2. Concept and Need for HWTS
3. How it can optimise SSWM
4. Pros and Cons
5. Steps of HWTS including Advantages and Disadvantages
Step 1 – Sedimentation
Step 2 - Filtration
Step 3 - Disinfection
Step 4 - Safe Water Storage
6. HWTS Promotion in Nepal
7. References
Household Water Treatment and Safe Storage Systems (HWTS)
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1. Water quality and safe drinking water
Water Quality
Physical:
• pH,
• Turbidity,
• Color,
• Taste & odor,
• TDS,
• EC,
• Etc.
Chemical:
• Iron,
• Arsenic,
• Ammonia,
• Nitrate,
• Manganese,
• Lead,
• Etc.
Bacteriological:
• Bacteria,
• Virus,
• Protozoa,
• Etc.
Household Water Treatment and Safe Storage Systems (HWTS)
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1. Water Quality and Safe Drinking Water
Drinking water treatment systems
Central treatment plants
• May be expensive & difficult to manage
• Possible contamination during
distribution
Household or Point-of-Use (PoU) treatment
• Inexpensive options are available
• Difficult to ensure proper use by all
Household Water Treatment and Safe Storage Systems (HWTS)
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1. Water Quality and Safe Drinking Water
Cross Contamination of Drinking Water
Source: ENPHO 2008
Household Water Treatment and Safe Storage Systems (HWTS)
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2. Concept and Need for HWTS
•
•
•
•
•
(source: WHO 2007)
Dramatically improves microbial water quality
Significantly reduces diarrhoea
Among most effective water, sanitation and health interventions
Highly cost effective
Can be rapidly deployed and taken up by vulnerable populations
Safe water can reduce diarrhea by 39 %
Sanitation can reduce diarrhea by 32 %
Hand washing with soap can reduce diarrhea by 45 %
According to WHO & UNICEF – HWTS can pay back up to US$ 60 for every US$ 1
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Household Water Treatment and Safe Storage Systems (HWTS)
invested
Source: WHO/UNICEF (2005)
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2. Concept and Need for HWTS
Concept
• Practice or process, not merely technology
• Process similar to centralised drinking
water treatment system but at the
household level
• Involves 4 main stages:
• Sedimentation
• Filtration
• Disinfection
• Safe water storage
Safe Water Storage
Source: CAWST (2009)
Household Water Treatment and Safe Storage Systems (HWTS)
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3. How it can optimise SSWM
• Water purification at household level
• Safe drinking water during Point-of-Use (PoU)
• Very important component of household-level water management
• Contributes largely to improved public health
• Low cost and simple HWT options are available suiting local
context of urban and rural settings
Household Water Treatment and Safe Storage Systems (HWTS)
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4. Pros and Cons
Pros:
Cons:
•Relatively inexpensive
• Difficult to monitor correct
operation and maintenance
(O&M) of technologies
•Independent from institutional
set-up or centralised systems
•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
Household Water Treatment and Safe Storage Systems (HWTS)
• High self-responsibility
required from 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
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5. Steps of HWTS: Step 1 - Sedimentation
Concept
• Physical treatment process used to remove small particles, which
make water cloudy
Household Water Treatment and Safe Storage Systems (HWTS)
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5. Steps of HWTS: Step 1 - Sedimentation
Option 1: Pot Settling
Advantages:
• Low costs (for free, if container is
already available)
• Simple and easy
Disadvantages:
• Time intensive
• Removes only partially removes turbidity
and pathogens
• Good settling requires multiple containers
Household Water Treatment and Safe Storage Systems (HWTS)
Source: CAWST (2009)
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5. Steps of HWTS: Step 1 - Sedimentation
Option 2: Coagulation and Flocculation
• Additives encourage settlement of suspended particles
• Forms larger particles which precipitate (fall to the
bottom)
• Easily removed by settling or filtration
Coagulants
• Chemical coagulants:
o PUR – Coagulation + Chlorination
o Alum (aluminum sulphate)
o PAC (poly aluminum chloride – liquid alum)
o aluminum or iron salts – i.e. ferric sulphate
• Plant coagulants:
o Moringa seeds
o Cactus
PUR
Source: Unknown
Cactus
Source: Unknown
Household Water Treatment and Safe Storage Systems (HWTS)
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5. Steps of HWTS: Step 1 - Sedimentation
Option 2: Coagulation and Flocculation
Advantages:
• Low costs
• Simple and easy
• Traditional/indigenous practice
• Removes turbidity and some pathogens
Moringa seeds
Source: Unknown
Disadvantages:
•Time intensive
•Doesn’t remove all pathogens
•Coagulants may not available everywhere
Alum block
Source: http://: www.cdc.org [Accessed: 26.06.2010]
Household Water Treatment and Safe Storage Systems (HWTS)
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5. Steps of HWTS: Step 2 - Filtration
Option 1: Straining
Source: IFRC, 2008
Up to 50 % reduction using eight layers of Sari cloth in Bangladesh (HUQ et al. 2010)
Household Water Treatment and Safe Storage Systems (HWTS)
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5. Steps of HWTS: Step 2 - Filtration
Option 1: Straining
Advantages:
• Low costs (free if extra cloths are available)
• Time required is minimal, simply the time it
Takes to pour water through the cloth
• Simple and easy to reduce turbidity
• Known to reduce risk of cholera
Disadvantages:
Source: IFRC, 2008
• Requires extra washing of cloth after use
• Cloth fibres loosen significantly the more they
are used
• Cannot remove all bacteria and viruses
Household Water Treatment and Safe Storage Systems (HWTS)
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5. Steps of HWTS: Step 2 - Filtration
Option 2: Biosand Filter
Works mainly due to 4
mechanisms:
1. Mechanical trapping
and sieving
2. Adsorption and
attachment
3. Predation
4. Natural death
(removes iron, turbidity,
pathogens & odour)
Source: http://www.hydraid.org/sol/index.htm [Accessed:
29.04.2010]
Household Water Treatment and Safe Storage Systems (HWTS)
Source: A. DOUCET,
(http://commons.wikimedia.org/wiki/File:Biosand_F
ilter_and_Canari.JPG [Accessed: 29.04.2010]
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5. Steps of HWTS: Step 2 - Filtration
Option 2: Biosand Filter
Source: ENPHO
Source: CAWST (2009))
Household Water Treatment and Safe Storage Systems (HWTS)
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5. Steps of HWTS: Step 2 - Filtration
Option 2: Biosand Filter
Advantages:
Disadvantages:
• Affordable - no ongoing cost
• Heavy, should not move after
installation
• Made from locally available
materials
• Durable
• High user acceptability
• Simple and easy to use
• Can effectively treat 60-80
litres/day
Household Water Treatment and Safe Storage Systems (HWTS)
• Turbidity should be less than
50 NTU
• Takes up to 30 days to develop
the biological layer
• Filter must be used almost
every day to maintain the
biological layer
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5. Steps of HWTS: Step 2 - Filtration
Option 3: Ceramic Candle Filter
Advantages:
Disadvantages:
• Made from locally available
materials
•Slower flow rate (1.5-3.0 litres
per hour)
• Easy to transport
•Breakable
• High user acceptability
•Need to be replaced when
damaged
• Simple and easy to use
•Need to clean filter regularly if
source water is dirty
•Can’t guarantee water is
pathogen free
Source: Uknown
Household Water Treatment and Safe Storage Systems (HWTS)
Source: CAWST (2009)
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5. Steps of HWTS: Step 2 - Filtration
Option 3: Colloidal Silver Filter
Disadvantages:
Advantages:
• Slower flow rate (1.5-3.0 litres
per hour)
•Low cost and looks beautiful
•Made from locally available
materials
• Not easily available everywhere
•Easy to transport
• Need to replace after 3 years
•High user acceptability
• Need to clean filter regularly
if source water is dirty
•Simple and easy to use
• Breakable
•High pathogen removal
Source: ENPHO
Household Water Treatment and Safe Storage Systems (HWTS)
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5. Steps of HWTS: Step 2 - Filtration
Arsenic removal with improved Biosand Filters (Surface Complexation)
The SONO Filter
•Meets WHO and Bangladesh standards
•Has no breakthrough
•Works without any chemical
treatment (pre- or post-)
•Without regeneration
•Without producing toxic wastes
•Produces 20–30 L/hour for daily
drinking and cooking needs of 1–2
families.
Source: http://www.jalmandir.com/arsenic/sono/sono-arsenic-filter.html [Accessed:
30.09.2010]
Source: http://www.jolkona.org/blog/wpcontent/uploads/2009/06/200801109.jpg
[Accessed:30.09.2010]
Household Water Treatment and Safe Storage Systems (HWTS)
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5. Steps of HWTS: Step 2 - Filtration
Arsenic removal with improved Biosand Filters (Surface Complexation)
The KANCHAN
Filter
Find out more on:
http://www.cawst.org/e
n/resources/pubs/sectio
n/1-education-materials
Household Water Treatment and Safe Storage Systems (HWTS)
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5. Steps of HWTS: Step 3 - Disinfection
Option 1: Chemical disinfection – liquid chlorination
Advantages:
• Provides residual chlorine for some
protection against re-contamination
• Inexpensive
Source: Uknown
• Widely available in different countries
• Easy to transport
• Relatively quick
• Simple and easy to use
Household Water Treatment and Safe Storage Systems (HWTS)
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5. Steps of HWTS: Step 3 - Disinfection
Option 1: Chemical disinfection – Liquid Chlorination
Disadvantages:
•Does not deactivate parasites like
Guardia, Cryptosporidium and worm
eggs
•Requires clear water to be most
effective
•Risk of by-product formation if water
has high organic content (i.e. surface
waters)
Source: CAWST (2009)
•Taste is unacceptable to some users
•Need to wait 30 minutes
•Users require to purchase chlorine on a continuous basis
Household Water Treatment and Safe Storage Systems (HWTS)
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5. Steps of HWTS: Step 3 - Disinfection
Option 2: Solar Water Disinfection (SODIS)
• PET (Polyethylene terephthalat) bottles or bags (1 to 2 litres) filled
with low turbidity water and exposed to sun light
• Optical inactivation (UV-A radiation):
o only slightly attenuated by clouds
o turbidity reduces amount of UV radiation that penetrates
water ( containers should not exceed depths of 10 cm)
• Thermal inactivation (infrared light):
o increased water temperatures reduces required exposure time
• Exposure time:
o 6 hours (bright to 50% cloudy sky) to 2 days (100% cloudy sky)
Household Water Treatment and Safe Storage Systems (HWTS)
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5. Steps of HWTS: Step 3 - Disinfection
Option 2: Solar Water Disinfection (SODIS) (adapted from http://www.sodis.ch/)
Step 1: Wash the bottle well the first time you use it
Step 2: Fill up the bottle fully and close the lid well
Step 3: Expose the bottle to the sun from morning
until evening for at least six hours
Step 4: The water is now ready for consumption
Household Water Treatment and Safe Storage Systems (HWTS)
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5. Steps of HWTS: Step 3 - Disinfection
Option 2: Solar Water Disinfection (SODIS)
Advantages:
• Free if plastic bottles are reused
• Relies on renewable energy and reduces need for traditional energy
• Ideal to treat small quantities of water
• Does not change the taste of the water
• Bottles are convenient for safe water storage and transportation
• Simple and easy to use
Household Water Treatment and Safe Storage Systems (HWTS)
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5. Steps of HWTS: Step 3 - Disinfection
Option 2: Solar Water Disinfection (SODIS)
SOlar Water DISinfectio
Disadvantages:
•Time-consuming (7 hours exposure)
SODIS uses locally available
•No residual effect
resources
••Requires
developing
relativelycountries
clear water have
to be most
effective
less than 30 NTU)
plenty(turbidity
of sunlight
••Requires
sunlight
is abundant
andtherefore
free
sufficient
solar radiation,
depends
on weather and climatic conditions
of charge
••Not
plastic
bottles
arevolumes
oftenofawater
useful to
treat large
waste produc
Inactivation of microorganism by
Household Water Treatment and Safe Storage Systems (HWTS)
UV-A- radiation and thermal treatment
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5. Steps of HWTS: Step 3 - Disinfection
Option 3: Boiling
Advantages:
• Effectively kills most pathogens
• Does not change the taste of the water
• Simple and widely accepted
Disadvantages:
• Time-consuming
• Relies on traditional energy sources such as
firewood (deforestation) and kerosene/gas,
• Linked to respiratory health issues caused by
indoor air pollution
• Water often tastes flat (fizzy)
Household Water Treatment and Safe Storage Systems (HWTS)
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5. Steps of HWTS: Step 4 – Safe water storage
• Safe storage involves storing water in a
suitable place using a clean and
appropriate container
• For safe water storage, an appropriate
container should have the following
qualities:
• Strong and tightly fitting lid or
cover
• Tap or narrow opening
• Stable base
• Durable
• Comfortable handle
• Allows air to enter as water is
poured
Household Water Treatment and Safe Storage Systems (HWTS)
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6. HWTS Promotion in Nepal
Promotion of HWTS by Government of Nepal
• GON initiated “National POU promotion
campaign” in 2005
• Intensive campaigns
• Set of Training materials
o fact sheets
o flex posters
o flip chart
o technical manual
• Mass media campaign:
o TV Spot
o radio jingles
o poster
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6. HWTS Promotion in Nepal
Private Public Partnership (PPP) Initiative
Strategy:
• Capitalise on the comparative advantages of
the private and public sectors
• Build local capacity
• Strengthen supply chain
• Awareness campaigns
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6. HWTS Promotion in Nepal
Innovative Promotion
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7. References
CAWST (2009): An Introduction to Household Water Treatment and Safe Storage, A CAWST Training Manual.
Alberta: Center for Affordable Water and Sanitation Technology (CAWST) Available at:
http://www.cawst.org/en/resources/pubs/file/78-participant-manual-complete-eng [Accessed: 08.04.2010]
CAWST (2009): Biosand Filter Manual, Design, construction, installation, operation and maintenance. Alberta:
Center for Affordable Water and Sanitation Technology (CAWST) Available at:
http://www.cawst.org/assets/File/Biosand_Filter_%20Manual_Version_10_No_Appendices_Sep09.pdf
[Accessed: 07.04.2010]
CAWST (2009): Biosand Filter. (=Household Water Treatment and Safe Storage Fact Sheet - Academic). Alberta:
Center for Affordable Water and Sanitation Technology (CAWST) Available at:
http://www.cawst.org/en/resources/pubs/section/1-education-materials [Accessed: 01.04.2010]
CAWST (2009): Household Water Treatment and Safe Storage Fact Sheet Compilation (Academic). Center for
Affordable Water and Sanitation Technology (CAWST) Available at:
http://www.cawst.org/en/resources/pubs/section/1-education-materials [Accessed: 01.04.2010]
ENPHO (2010): Water Quality in Nepal: Compilation of WQ studies conducted by ENPHO with various agencies.
ENPHO (2008): Water Quality Testing at five municipalities in Nepal.
HUQ, A., YUNUS, M., SOHEL, S.S., BHUIYA, A., EMCH, M., LUBY, S.P., RUSSEK-COHEN, E., BALAKRISH
NAIR, G., BRADLEY SACK, R., COLWELL, R.R. (2010): Simple Sari Cloth Filtration of Water Is Sustainable
and Continues To Protect Villagers from Cholera in Matlab, Bangladesh. In: mbioasm, Volume 1, Issue 1.
Available at: http://mbio.asm.org/content/1/1/e00034-10.abstract [Accessed: 29.10.2010]
WHO (2007): Combating Waterborne Diseases at the Household Level. Geneva: World Health Organisation
(WHO)
WHO/UNICEF (2005): Joint Monitoring Programme for Water Supply and Sanitation. Water for Life: Making it
Happen. Geneva: World Health Organisation (WHO)
Household Water Treatment and Safe Storage Systems (HWTS)
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Water Management & Agriculture”
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Household Water Treatment and Safe Storage Systems (HWTS)
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