FS1 waterquality FINAL - sswm.info · PDF fileFS1_waterquality__FINAL.indd 2 10/22/2008 8:25:54 AM. ... every episode reducing the calorie and nutrient uptake, setting back growth

ater being a universal solvent, dissolves various substances with which it comes into contact,

including minerals, chemicals, soil and micro-organisms. Hence, it is very rare to fi nd pure water in nature free of any other elements. The water we drink also contains various elements mixed into it, the exact composition of which depends on the source of water and the way it is handled and stored. Some of the minerals found in water are good for the human body, but water from certain sources may contain elements in high concentrations that they have adverse eff ects on the human body. Generally, three types of elements — physical, chemical and biological — are found in water.

Water becomes contaminated primarily in two ways : (a) through human activities and (b) by natural processes. Open defecation, discharge of sewage or industrial effluent, and improper use of chemical fertilizers and

Water Quality

FACT SHEET: WATER QUALITY1

W

pesticides are some of the human activities that pollute water sources. Natural processes that pollute water include mixing of soil, sand, leaves or naturally occurring chemicals such as arsenic and iron in water.

While chemical contamination may be perceived as the most serious form of contamination, the most threatening contamination is caused by harmful micro-organisms or pathogens. Th ese micro-organisms are responsible for the outbreaks of various water-borne diseases and causes 10 times more deaths than by chemical contaminants. Th e consumption of unsafe drinking water together with poor sanitation and hygiene practices annually causes 1.8 million children under fi ve years of age to die due to water-borne disease. Water is considered to be safe if it has no pathogenic organisms and other chemicals are found within concentration range set under WHO guidelines or the country's national guidelines.

What is safe and good quality drinking water ?

Water containing diff erent substances in concentrations that are

not harmful to the human body can be considered good quality

water. To determine the quality of drinking water, individual

countries have their own National Drinking Water Quality Standards

that prescribe a range of permissible concentrations of various

physical, chemical and microbial parameters. Generally, safe

drinking water must have the following characters:

Aesthetically acceptable in appearance, smell and taste •Free or within safe limit of harmful chemicals •Free of harmful micro-organisms •

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MDG and water quality

In 2004, a total of 5.3 billion people (83% of the world’s population) used water from improved sources, up from 4.1 billion (78%) in 1990. Because of population growth, however the number of people unserved has not changed substantially since 1990. About one sixth of the world's population or 1.1 billion people do not have access to improved drinking water. MDG target 10 calls for reducing the proportion of people without sustainable access to safe drinking water by half by 2015. Reaching this target implies tackling both the quantity (access) and quality

(safety) dimensions of drinking water provision. The progress towards reaching this target is indicated by the proportion of households reporting the use of improved water supplies such as piped household connections or protected water sources. While access to improved supplies appear high, various studies suggest that, depending on the local conditions, a signifi cant proportion of water from these sources may be contaminated. To meet the MDG goal, it is of utmost importance to provide options for access to safe water at the household level.

Various substances found in water and possible problems caused by themPARAMETER WHO DRINKING WATER QUALITY STANDARDS POSSIBLE PROBLEMS

Physical Characteristics

Turbidity 5 (10) NTU Visibly unclear water and makes diffi cult to eliminate germs

Color 5 (15) TCU Excess color indicates presence of undesirable substances mixed in water

Taste and smell Not objectionable May alter the taste

pH 6.5 – 8.5 Low pH causes corrosion of pipes and high pH may decrease the eff ectiveness of chlorination

Chemicals (mg/l)

Iron 0.3 (3) Stains clothes, utensils, pipes etc.

Manganese 0.4 Causes black stains

Ammonia 1.5 Cretes bad odor

Nitrate 50 Can cause Blue Baby Syndrome in children

Fluoride 0.5 – 1.5 Weakens teeth and bones

Total hardness 500 Clogs pipes and prevents soap from lathering

Arsenic 0.05 Can cause skin, kidney, liver, and urinary bladder cancer and other adverse eff ects.

Microorganisms (Col/100 ml)

E. coli 0 May cause water-borne diseases like diarrhoea, typhoid, cholera, dysentery, hepatitis A

Total coliform 0 (95% of the sample) May cause water-borne diseases like diarrhoea, typhoid, cholera, dysentery, hepatitis A

NOTE: Units within brackets indicate the acceptable units when there is no other source of water. NTU is Nephelometric Turbidity Unit, a measurement of the turbidity

of water and TCU is True Color Unit. Col /100ml is Colonies per 100ml


Coverage of improved drinking water sources in 2004

Microbes present in contaminated water and diseases caused by themMICROBES MICROORGANISMS CAUSING DISEASE DISEASES

1. Virus

Rotavirus Diarrhoea, gastroenteritis

Hepatitis A virus Hepatitis A

Enterovirus Meningitis

Poliovirus Polio

2. Bacteria

Escherichia coli Diarrhoea

Salmonella typhi Typhoid

Salmonella paratyphi Paratyphoid

Shigella sp. Dysentery

Vibrio cholerae Cholera

3. ProtozoaGiardia Giardia

Entamoeba histolytica

Cryptosporidium parvum

Amoebiosis

Gastroenteritis

Percentage of population

using improved drinking water

sources

Less than 50%

50%-75%

76%-90%

91%-100%

Insuffi cient data

Source:- WHO/UNICEF report 2004


was also found in 47 percent of 14,394 tube wells tested by Nepal Red Cross Society and Environment and Public Health Organization (ENPHO), indicates that water in both surface and ground water is not safe to drink.

Water quality is also a problem in big cities like Kathmandu. Various studies have shown that piped water in Kathmandu is often chemically and biologically polluted. Water test performed in 2005 by ENPHO in Kathmandu Valley covering 138 deep tube wells, 160 shallow tube wells and 91 dug wells revealed that most of them contain iron, manganese, nitrate, ammonia and micro-organisms in concentrations exceeding the guideline values set by WHO. According to a recent study, only about 10 percent of the households in Nepal treat their drinking water. Even in major urban centers like Kathmandu, only about 29% treat their drinking water through various means.

People’s Perception on Water Quality

Research conducted in various parts of Nepal have revealed that

drinking water is often polluted by biological and chemical

contaminants. However, a majority of the people are unaware of

such contamination. Recently, UNICEF conducted a survey of 1800

households in four districts of Nepal and found that majority (75

percent) perceives no problem in their drinking water. Similarly,

74 percent of the respondents considered safe water as water

without any visible contamination, while 36 percent considered

water safe if it is without sand and soil and 26 percent considered

odorless water as pure and safe drinking water. Most of the people

were unaware of the fact that even clear water can contain disease

causing pathogens or harmful chemicals.

Methods of Testing Water Quality

The amount of harmful micro-organisms or

chemicals in water cannot be measured by

simply observing, tasting or smelling water.

Normally, there are two methods for testing water

quality.

LABORATORY ANALYSIS — Drinking water quality tests

conducted in laboratories equipped with modern instruments and

qualifi ed technicians are more reliable. However, lab tests are

often expensive, require trained manpower and can be time

consuming.

FIELD TEST KIT — There are diff erent types of fi eld test kits that

can be used for testing water quality in the fi eld. Such test kits

are easy to use and give quick test results, but the results may not

be as accurate as laboratory tests.

The quality of drinking water in Nepal

Although water quality tests are not done regularly in Nepal, the fi ndings of the few tests done so far indicates that most of the water sources in the country are contaminated by disease causing pathogens and some by chemicals. According to a survey conducted in 2001 by the Rural Water Supply and Sanitation Fund Development Board (Fund Board), 88 percent of samples from gravity water supply schemes in hill areas had microbial contamination. Similarly, a survey conducted by Department of Water Supply and Sewerage (DWSS), found microbial pollution in 56 percent of tube wells in the Terai region. Microbial contamination


t is said that water is life but the fact remains that water-borne diseases such as diarrhoea result in the

death of more than 1.8 million children below fi ve years each year in the world. Th is fi gure implies that on average ,one child dies due to diarrhoea every 15 seconds Providing safe and reliable water services to 1.1 billion people who currently lack this service is an essential long term goal that will yield great health and economic benefi t. Less known is the signifi cant contribution that household level water quality interventions can make to immediately improve the health of the most vulnerable.

Health is compromised when harmful bacteria, viruses and parasites contaminate drinking water either at the source, through seepage of contaminated run-off water, or within pipped distribution system. Moreover, unhygienic handling of water during transport or within the home can contaminate previously safe water. For these reasons, many of those who have access to improved

water supplies through piped connections, protected wells or other improved sources are, in fact are still exposed to contaminated water.

Water can also be contaminated from high concentrations of various chemicals. Groundwater may contain chemicals like iron, manganese, ammonia and nitrates. Though chemical pollutants have adverse impacts on health, microbial contamination is often considered to be more serious, as it is more common and causes immediate health impacts.

^

Household Water Treatment Techniques

FACT SHEET: HOUSEHOLD WATER TREATMENT TECHNIQUES2

45% through washing hands with soap and water

Ways to prevent diarrhoea

39% through safe drinking water32% through improved

sanitation 25% through improved water supply

I

Source: WHO, 2007

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at the household level together with proper hygiene practices.

The “F” diagram shown below indicates the route pathogens travel from feaces through fi ngers, fi eld, fl ies, food and fl uid (water) to the human body. Th e diagram also shows three principle ways of blocking this pathway. Among these, point of use water treatment ensures that pathogens do not enter the body through drinking water. According to WHO, diarrheal episodes are reduced by 25 percent through improving water supply, 32 percent by improving sanitation, 45 percent through hand washing with soap and by 39 percent through household water treatment.

Household water treatment options

Water that appears clean may not be safe as thousands of micro-organisms invisible to naked eyes may exist in water, Th us household water treatment intervention at point of use is essential. In addition, it is one of the most eff ective water, sanitation and health interventions, highly cost effective and can be quickly introduced to the large population and adopted by the most vulnerable population. While various alternatives for household water treatment, exists, some of these are more simple, inexpensive and effi cient than others and are discussed as follows :

Why Treat Drinking Water?

Diarrhoea occupies a leading position among diseases as a cause of death and illness. Children suff er the most with every episode reducing the calorie and nutrient uptake, setting back growth and development. Ninety percent of diarrheal deaths occur in children under 5 years , mostly in developing countries. WHO estimates that 94 percent of diarrheal cases are preventable through modifi cations to the environment, including interventions to increase the availability of clean and safe drinking water and to improve sanitation and hygiene.

In developing countries while access to water supply has improved substantially, the quality of drinking water is mostly ignored. As a result, most drinking water sources is contaminated and water must be treated in order to ensure that it is safe for consumption. Generally, central water treatment systems are expensive and complicated to operate. Rural communities served by small schemes can neither aff ord central treatment nor manage operation. While some large water supply systems may have water treatment facilities, the water supplied may still be contaminated due to poor distribution network and poor management. Furthermore, water can be contaminated in the house due to unclean storage vessels or poor personal hygiene. Th erefore there is a need to treat water

HumanFood

Finger

Flies

Field

Fluid

Feaces

Use of toilet

“F” Diagram

Hand washing with soap and water

Water treatment

0

500

1000

1500

2000

2500

3000

3500

4000

RespiratoryInfections

HIV/AIDS Tuberculosis Malaria MeaslesDiarrhoealDiseases

3963

Deat

hs (0

00s)

2777

1272

611

17981566

Source: 2004 World Health Report

Leading causes of deaths from infectious diseases


A. BoilingThis is the most common method of household water treatment. Boiling water kills harmful micro-organisms that cause

diseases such as dysentery, diarrhoea, cholera and typhoid. According to WHO, water

needs to be heated until the appearance of the fi rst big bubble to ensure that it is pathogen free. Boiled water should be kept covered in clean vessel to prevent it from being contaminated again.

B. FilterDifferent types of filters, such as the candle filter, the colloidal silver fi lter, and the biosand fi lter are available in the market to treat water.

Candle fi lterTh is is a popular technology available in many places. The filter has two compartments. Th e upper vessel has one or two candles, which remove turbidity and some of the pathogens and the fi ltered water is stored in the bottom compartment. Th is type of fi lter is readily available and easy to use but does not completely remove all micro-organisms. Th erefore, this technique must be used along with other water disinfection methods.

Biosand fi lterBiosand fi lter has a sand layer where a biofi lm naturally grows in certain period. It removes turbidity, iron, odor and removes most of the pathogens in water. Th e fi lter can be installed by a trained person using local materials.

Th e container of the fi lter is made of either cement or plastic. Because of its capacity to fi lter large amounts of water as well as its easy operation and maintenance, the popular i ty o f th i s f i l ter i s

increasing.

Kanchan arsenic fi lterKanchan arsenic fi lter is a modifi ed version of the biosand filter that removes arsenic as well as turbidity, iron, odor and pathogens from groundwater. Use of this fi lter is being promoted in various arsenic-aff ected areas of Nepal and the Asian region.

Colloidal silver fi lterTh is fi lter is similar to the candle fi lter with two compartments and a candle or disc fi lter on the top compartment. Th e specialty of this fi lter is that the candle

or disc is coated with colloidal silver that kills pathogens in water. In Nepal, currently

two types of colloidal silver fi lters are available - ‘Safa Filter’ and ‘SBL Filter’ are available. Countries like Cambodia, Nicaragua and Ghana are also promoting CS filters in vulnerable areas.

C. Chlorine solutionChlorination which kills germs is a widely used method for disinfecting water. Water need not be boiled or fi ltered once it is chlorinated and the residual effect of chlorine prevents it from being re-contaminated. Th e correct dose of chlorine solution should be added to ensure that the treatment process is eff ective. Large quantities of water can also be treated using this method.

At present, two types of chlorine solutions are available in the Nepalese market namely ‘Piyush’ and ‘WaterGuard’. Piyush is a 0.5 percent chlorine solution

available in 60-ml plastic bottles. Th ree drops of Piyush can treat one liter of water.

WaterGuard is a 0.72 percent chlorine solution available in 240-ml plastic bottle. Aquatab, a chlorine tablet, is also


should be exposed to the sunlight for 6-7 hours and if weather is totally cloudy, the bottle should be exposed for two days. Th e synergetic eff ect of ultra-violet rays (UV-A) and heat from the sun destroys any harmful micro-organisms existing in the water.

Safe storage of drinking water

Following treatment, water should be stored safely and handled hygienically in order to avoid recontamination. Water should be kept covered in clean vessels and served only from clean vessels. Glasses and water vessels should be washed properly before use.

one option for chlorinating water and is available in the tablet that could treat 5 liters of water. Th ese tablets are also available to treat larger volume of water. After adding the correct dose of chlorine, the water will be safe for drinking after 30 minutes.

D. SODISSolar water disinfection (SODIS) is a simple, inexpensive, and reliable household water treatment option which requires only a clean plastic bottle and

sunlight. In this method, water is placed in a clean, scratch and damage free transparent

plastic bottle (diameter not to exceed 10 cm) and exposed to sunlight. On a bright or partially cloudy day, the bottle

Household water treatment techniquesMETHOD OF TREATMENT ADVANTAGES DISADVANTAGESBoiling • Kills almost all germs • Consumes fuel (wood, kerosene oil etc.)

• Possibility of environmental problems (deforestation, air pollution)

• Time consuming

• Changes taste

Chlorination (such as Piyush,

WaterGuard & Aquatab)

• With accurate dosing eliminates almost all germs • Depends on chemical

• Can change the taste and smell if used in excess

• Not available in all places

Candle fi lter • Does not use chemicals or fuel

• Easy to use

• Costly (NRs. 800 to 2000*)

• Only about 3 liters of water can be fi ltered in an hour

• Germs not completely eliminated

Colloidal silver fi lter • Germs can be killed

• Easy to use

• Costly (NRs. 400 to 800)

• Only about 3 liters of water can be fi ltered in an hour

• Filter candle can break

Biosand fi lter or

Kanchan arsenic fi lter

• Does not use chemicals or fuel

• Removes micro-organisms, odor, iron and arsenic

• Can fi lter large amount of water at a time

• Expensive (About NRs. 1500)

• Technical support needed for installation

SODIS • Destroys micro-organisms

• Does not use chemicals or fuel

• Zero cost

• Weather dependent.

• Chemicals are not removed

• Water with high turbidity cannot be treated

For further information: http://www.who.int/household_water/en/• http://www.who.int/water_sanitation_health/monitoring/improved/en/

*Conversion Rate 1 USD = NRs. 70 (Approx.)


How does Colloidal Silver fi lter remove the pathogens?

Colloidal silver alters the rate at which chemical processes in the cells of the micro-organisms takes

place, thereby decreasing their ability to use oxygen and kills harmful micro- organisms. It is not

toxic to the human body and causes no side eff ects.

raditionally, water has been purified from visibly impure substances such as leaves, soil, sand and

insects and some micro-organisms by straining through cloth or sand or simply by settling the water. Today, various kinds of fi lters like the Candle Filter, the Colloidal Silver Filter, the Biosand Filter are available in the market for this purpose.

A candle fi lter made of porous ceramic material, is a well known water treatment technology. Th e fi lter set consists of two containers. Th e upper container holds one or two ceramic candles which fi lters the water, while the lower section collects the water. Generally, the fi lter containers are made of aluminum, steel or clay while the candle is made of ceramic. Because visible matters and certain

micro-organisms in the water cannot pass through the fi lter, the water is visibly

clean though it may not remove a l l p a t h o g e n i c m i c r o -

organisms.

Colloidal Silver Filter

Colloidal Silver Filter is an improvement on a candle fi lter that kills all germs in water. Instead of a simple clay candle, this fi lter uses a clay candle or disc that is coated with colloidal silver. Th e silver coating in the candle or disc kills germs and eff ectively disinfects water. Th is technology was developed by Central American Institute for Industrial Research and Technology (ICAITI) in 1981 in Guatemala and has extensively promoted in Nicaragua since 1998 by Potters for Peace. Colloidal silver fi lters are now in use in diff erent parts of Central America, Africa and Asia.

FACT SHEET: FILTER3

T

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Advantages of Colloidal Silver FiltersKills disease-causing micro-organisms ( bacteria, virus etc) •Filters up to two to three liters of water every hour •Easy to use •Portable •Does not increase temperature of water •

How to use the fi lterClean the fi lter with clean water and let it dry naturally •Assemble the fi lter as per the instruction •Fill the upper part with water •Dispose of the water fi ltered for the fi rst time •Pour fresh water into the fi lter and use it for drinking •

LimitationsClay candles and container can break if not properly handled •This fi lter may not be available in all places •Candles or discs could last for only about 1-2 years and need to •be replaced

Points to be notedThe fi lter should be placed on a fl at surface away from direct •sunlight.

While fi tting (esp. Safa fi lter), the candle and tap should be •fi tted tightly to avoid leakage from it.

The candle or plate disc should be thoroughly cleaned from •time to time using a soft toothbrush or other soft brush without

scrubbing too hard.

Never use soap for cleaning the candle. •After cleaning, the fi lter container should be washed from both •sides with fi ltered water.

Filter candle should never be boiled. •The outlet of the filter should not be touched with dirty •hands.

Water with high turbidity or iron content should be screened •or settled before pouring in the fi lter

Colloidal Silver Filter in Nepal

Colloidal Silver Filters were piloted in Nepal from 2002 to 2004 in local villages by International Development Enterprises-Nepal (IDE) . The filter is currently being manufactured and marketed as “Safa Filter” by Thapa Molds and Dyes. Similarly, a clay vessel Colloidal Silver Filter having a disc filter is also being produced and marketed by Madhyapur Clay Crafts with support from Solution Benefi ting Life.

For further information visit: www.pottersforpeace.org | www.solutionsbenefi tinglife.com

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iosand Filter is a simple household drinking water treatment technique for removing micro-organisms,

iron, odor and turbidity present in water. Th is technique was fi rst developed by Dr. David Manz of Canada in 1993 by modifying the principles of the widely used slow sand fi ltration technology so that could be used to treat water at household level. Currently, more than 20,000 biosand fi lters are being used in 35 developing countries. A well-trained individual can install this fi lter at the local level by arranging layers of gravel and sand in concrete or plastic containers following strict guidelines.

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Biosand Filter

B

Method1. Place the collecting vessel below the fi lter outlet.2. Remove the fi lter lid and slowly pour the water to be

fi ltered.3. Th e fi ltered water collects in the vessel placed below

the outlet.4. Th e fi lter and its surroundings should be kept clean

to avoid contamination.5. A concrete biosand fi lter purifi es 25-30 liters of water

in one hour whereas a plastic biosand fi lter purifi es 15-20 liters in one hour. This amount would be suffi cient for drinking and cooking purposes even for a large family.

Materials used to make the fi lterCONCRETE BIOSAND FILTER PLASTIC BIOSAND FILTERMold to make the fi lter, cement,

gravel and sand50 liter plastic bucket

Pipe fi ttings Pipe fi ttings

Diff user plate or basin 17 inch plastic basin

6-12 mm gravel 6-12 mm gravel

3-6 mm rough sand 3-6 mm rough sand

1 mm fi ne sand 1 mm fi ne sand

FACT SHEET: BIOSAND FILTER4

Diffuser plate

WaterBio-film

Lid

Pipe

Filteredwater

Fine sand

Coarse sand

Gravel

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For further information visit: www.enpho.org | www.cawst.org | www.mit.edu

Process of Elimination of Micro-organisms

Biosand fi lter utilizes physical and biological processes to eliminate micro-organisms. Th e fi ne sand particles in the fi lter traps large micro-organisms. Within 1-3 weeks of using the fi lter, a biological layer called a biofi lm develops over the layer of sand. Th e large micro-organism in the biofi lm destroys small micro-organisms. In this biofi lm, about 5 cm of water should always remain over the layer of sand. Since formation of the biofi lm requires about two weeks, the fi lter may not remove the micro-organisms effi ciently during that time .

Process of Removing Turbidity and Iron

Water may contain high levels of iron and solid particles. When iron in water comes in contact with oxygen, a yellowish, insoluble substance is produced. Once this water is poured into the fi lter, most of the insoluble iron and solid particles are trapped on the fi ne sand by physical straining. Various studies have shown that a biosand fi lter can remove between 90 and 99+ percent of the turbidity and iron in water.

Large micro-organisms are trapped on

top of the sand layer.

Small micro-organisms are de-stroyed by large micro-organisms in the biofi lm on top of the sand layer.

Kanchan Arsenic Filter (KAF) is a modifi ed

Biosand Filter designed to remove

micro-organisms, turbidity, iron,

odor and arsenic from water. In

this filter, gravel and sand are

arranged in layers. Above this a

diff user plate containing 5 kg of

iron nails covered with brick

chips is placed. This fi lter works on

the principle of slow sand fi ltration

and iron hydroxide adsorption. KAF was

developed through the joint efforts of

Massachusetts Institute of Technology (MIT) of USA, Environment

and Public Health Organization (ENPHO) and Rural Water Supply and

Sanitation Support Programme (RWSSSP) of Nepal. So far more than

5000 such fi lters have been installed in arsenic aff ected districts in

the Terai and the popularity of these fi lters is increasing.

Iron particles are trapped on top

of fi ne sand layer.

Sand Particles

IronIron

Kanchan Arsenic FilterHow is arsenic removedWhen iron nails are exposed to air and water, they rust very quickly

producing ferric hydroxide particles. These particles are an excellent

absorbent of arsenic. When arsenic contaminated water is poured

into the fi lter, arsenic is adsorbed onto the fi ne rust particles which

are then fl ushed into the sand layer below. The arsenic loaded iron

particles are trapped in the top of the sand layer and arsenic is

removed from the water.

Effi ciency of Biosand Filter and Kanchan Arsenic FilterPARAMETERS REMOVAL RATES

Arsenic 85% to 95+%

Disease causing micro-organisms 60% to 100%

Turbidity 80% to 95+%

Iron 93% to 95+%

Rate of fl ow 15 to 20 liters an hour

Working period of iron nails At least 3 years

For further information visit: www.enpho.org | www.cawst.org | www.mit.edu/watsan

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olar Water Disinfection (SODIS) is a simple, inexpensive and reliable method for household

water treatment. SODIS is done by fi lling a clean, scratch and damage free transparent plastic bottle (maximum 10 cm in diameter) with water and exposing it to direct sunlight. It uses the synergetic eff ect of ultra-violet (UV-A) rays and heat to eliminate disease causing micro-organisms present in the water.

Professor Aftim Acra at the American University in Beirut discovered SODIS in 1985. In 1991, the Swiss Federal Institute of Science and Technology (EAWAG/SANDEC) conducted further research and started promoting the method in developing countries. Currently, SODIS is being used in over 20 countries including Nepal.

Points to be noted

Eff ects of UV-A and heatTh e combination of ultra-violet rays (UV-A) and heat from solar energy disinfects the water. Th e ultra-violet

Solar Water Disinfection (SODIS)

Fill the bottle to the

mouth with water and

tighten the cap.

Expose the bottle to full sunlight in an

inclined position for about seven hours.

The bottle must be kept exposed for

two days if it is cloudy

S

Method

Take a one or two liters

transparent plastic bottle,

remove its label and clean it

thoroughly, including the cap.

Now, the water is

ready to drink

FACT SHEET: SODIS5

rays attack the cells of harmful micro-organisms like virus, bacteria and yeast present in water and destroy them. Heat from the sun creates an adverse situation for the organisms by increasing the temperature.

Eff ects of weather and climatic conditionsBottles should be exposed for at least seven hours if the sky is clear or 50 percent cloudy. If it is fully cloudy, bottles should be kept outside for two full days. Even if ultra-violet rays penetrate the clouds, it takes more time to destroy organisms at lower temperatures. Air pollution does not aff ect the eff ectiveness of SODIS.

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Bottles for SODISTo perform SODIS, a one or two liters transparent plastic (PET–Polyethylene terephthalate) bottle with a diameter not more than 10 cm is needed. Bottles such as Mineral water, Coke, Fanta and Pepsi bottles may be used. In these bottles sun’s ultra-violet rays can easily penetrate and destroy micro-organisms. SODIS may not be effective if the bottle is crushed, scratched, old or colored, as UV-A rays cannot eff ectively penetrate through the plastic. For the same reason, SODIS is also ineff ective in thick-glass bottles. After SODIS, using the water directly from the bottle reduces the possibility of re-contamination. If fungus develops, the bottle can be cleaned by using rice grains or powdered egg shells.

For further information visit: www.sodis.ch | www.enpho.org

SODIS in Nepal

In Nepal, a study on the eff ectiveness of SODIS was conducted by

Environment and Public Health Organization (ENPHO) in 2000 with

the support of the Department of Water Supply and Sewerage

(DWSS), UNICEF and EAWAG/SANDEC. Since 2003, SODIS has been

promoted in various parts of the world by various government and

non-government agencies.

National and International Recognition of SODIS Achieved fi rst position in the World Water Forum Contest in

2000.

Recognized by World Health Organization (WHO) in 2001.

Received Best Certifi cate Award from UN Habitat in 2002.

Received Energy Globe Award from United Nations in 2004.

Included in Nepal's National Sanitation Guide.

Included in Environmental Science Teacher's Guide by the

Government of Nepal.

“SODIS Success Story” was included in a progress report of

Nepal Millennium Development Goals

Turbidity of WaterIf turbidity of water exceeds 30 NTU (Nephelometric Turbidity Unit), sunlight will be unable to destroy the

h a r m f u l o r g a n i s m s completely. Hence, turbid

water should be properly settled and fi ltered before disinfecting by

SODIS. In case there is excess iron in the water, it should be poured into a

vessel and left uncovered for a night and fi ltered or settled before conducting SODIS.

Eff ects of using Plastic BottlesAccording to a study done by EAWAG/SANDEC, certain harmful chemicals like DEHP (Diethylhexyl adipate) and DEHA (Diethylhexyl phthalate) are created when plastic bottles are kept at the temperature of 60 degrees centigrade. But the concentration of these chemical are nominal compared to the guideline values set by WHO and do not aff ect human health.

Advantages of SODIS

This technique helps to prevent water-borne diseases like

diarrhoea, hepatitis-A and typhoid as it destroys harmful

micro-organisms. Moreover, the chances of re-contamination

are reduced by drinking water directly from the bottle after

performing SODIS.

Water can be treated at zero cost.

Water treated using SODIS is tasty

Once SODIS has been performed, the water can be used for

up to seven days if the lid is carefully tightened

SODIS is simple and does not require highly technical

knowledge.

SODIS bottles can be easily moved from one place to

another.

As the bottles can be reused, SODIS helps in waste

management.

The use of renewable solar energy helps to conserve the

environment.

isly

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isinfection of drinking water by mixing chlorine solution is called chlorination. Chlorine was used

for the first time in 1850 when John Snow used it in London’s water distribution system to combat cholera . Similarly, American cities like Chicago and New Jersey started to use chlorination around 1908, a step which brought significant decrease in the number of deaths caused by cholera, typhoid, diarrhoea and hepatitis A. Today chlorination is used to treat most drinking water in the world since it is easy, inexpensive and reliable. In addition to destroying harmful micro-organisms, chlorination also reduces the amount of iron, manganese and hydrogen sulphide in water. Together with the use of chlorine on a large scale, chlorine is being packaged in small quantities for household use and is used widely in both developing and developed countries.

Use of chlorine

Th e correct amount of chlorine solution must be used. If the concentration of chlorine is inadequate the solution may fail to destroy all the harmful micro-organisms and if in excess, health may be adversely aff ected. Only an appropriate amount of chlorine can destroy all harmful micro-organisms and provide a safe amount of residual chlorine. Chlorine that does not combine with other components and remains in the water is called “Free Residual Chlorine” (FRC). According to WHO guidelines, the FRC concentration in drinking water should be between 0.2 to 0.5 mg/L.

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Chlorination

Advantages

• Th is is a simple, inexpensive and reliable technique.• Since chlorinated water need not be boiled, energy and

resources are saved.• Chlorine destroys almost all harmful micro-

organisms.• Because of the residual eff ect of chlorine, the chance

of recontamination is low.

Points to be noted

• Th e correct dose of chlorine solution should be used.• Direct contact of chlorine solution to body parts and

clothes must be avoided.• In case the body comes into direct contact with

chlorine solution, the area must be washed immediately with plenty of water and medical treatment obtained at the nearest health post.

Chlorination in Nepal

Chlorination, traditionally used to centrally treat water in the pipped

water supply system was introduced for household treatment of water

in 1994 by Environment and Public Health Organization (ENPHO) with

the brand name “ Piyush”. The product was retailed at medical outlets

on a non profit basis and with special focus on emergency relief.

Another chlorine product “Water Guard”, was introduced in Nepal in

2005 by Population Services International (PSI). Piyush is a 0.5 percent

chlorine solution packaged in 60 ml plastic bottles, Water Guard is a

0.72 ml chlorine solution available in 240 ml plastic bottles. Besides

these two solutions, Aquatab, a chlorine tablet produced by Medentech

Ltd, Ireland, which was initially used only for emergency relief in Nepal,

is now available in the Nepalese market. Aquatab comes in tablets of

diff erent sizes to treat 1 liter, 5 liters and 25 liters of water respectively.

Aside from these commercial products, water can also be treated at the

community level by mixing chlorine in water tanks, wells and household

vessels.

FACT SHEET: CHLORINATION6

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For further information visit: www.enpho.org | www.medentech.com | www.psi.org

When chlorine is mixed in water, the following reaction takes

place:

The hypochlorous acid readily destroys bacteria, oxidizes organic

matter, dissolves colour and destroys “chloramines” derived from

ammonia. It takes about 30 minutes to do this work and make water

safe to drink.

How to prepare a chlorine solutionWhere chlorine solution is not available in the market, one can make

it by using a solution of bleaching powder, normally available in

local community health posts.

• Place 40 gm (about 5 tea spoons) of bleaching powder in

plastic mug and add some water to make a thick paste

• Add 1 liter of water and stir the solution thoroughly

• Put the solution aside for 5 minutes to settle. A clear chlorine

solution will appear at the top with some residue settling at

the bottom

• Carefully pour the clear chlorine solution to a colored plastic

jar and seal tightly. Throw the residue in the drainage.

• The prepared chlorine solution is 1% chlorine solution. Store

the solution in a dark place away from children.

Cl2 + H

2O

Chlorine + Water

HOCl + HCl

Hypochlorous acid

Hydrochloric acid

Chlorine demandChlorine dosage CombinedChlorine residual Residual Chlorine

Minerals

Metal

Slime and Organic Matter

How to use a chlorine solution

• Three drops of 1% chlorine solution can treat 1 liter of drinking

water.

• One liter of chlorine solution can treat 10,000 liters of water.

• After determining the volume of a water tank, the exact

chlorine dose can be determined. For example: How much

chlorine solution is required to treat 2,000 liters of water?

For 10,000 liters of water – 1 L chlorine solution; For 1 L water – 1/10,000 L chlorine solution; and For 2000 L water– 1/10,000 x 2,000 L = 0.2 L or 200 ml of chlorine solution is

required

• The water will be safe to use 30 minutes after adding chlorine

solution

• Calculating the water tank volume

i. For a rectangular water tank Volume of tank (V) = [Length (L) x Breadth (B) x Height

(H) of tank] x 1000 L

Example:

Given that L=2 m; B=2 m & H=3 m

V = L x B x H x 1000L = 2 x 2 x 3 x 1000 L

Therefore, Volume of the tank (V) = 12,000 L

And to treat 12,000 L water – 1/10,000 x 12,000 L = 12 L

of chlorine solution is required

ii. For cylindrical water tank Volume of tank (V) = [π x r2 x Height (H) of tank] x

1000 L,

Where “r” is the radius of the tank, which could be

calculated by: diameter/2, & π = 22/7

Example:

Given that r= 1 m; H=3 m

V = (π x r2 x H) x 1000 L = 22/7 x 1 x 1 x 3 x 1000 L

Therefore, volume of the tank (V) = 9428.5 L

To treat 12,000 L water – 1/10,000 X 9428.5 L = 0.95 L

or 950 ml of chlorine solution is required

How Does Chlorine Work?

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