By Dieuseul Istache
&
John C. Rigdon
Clean Water for Life
2nd Printing - October 2024 0/0/0/0/KN
© 2019 Words R Us. This book is made available under a Creative Commons Attribution-Share Alike 4.0 International License. (CC BY-SA 4.0)
Published by:
Words R Us
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Davenport, IA 52806
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EMAIL: editor@wordsrus.us
Tel. (678) 739-9177
Contents
Introduction. 8
Dirty Water Can Make You Sick. 10
What Makes Water Unsafe?. 11
Timothy's story. 11
Understanding why Timothy died.. 12
A simple story about how germs travel 13
How germs and worms spread disease. 14
How diarrhea diseases spread.. 15
Diarrhea diseases. 16
. Signs. 16
Treatment for diarrhea diseases. 18
Diarrhea and dehydration. 18
Signs of dehydration. 19
Made with powdered cereal and salt. 20
Guinea worm... 23
Signs. 23
Blood flukes (schistosomiasis, bilharzia, snail fever) 24
Blood flukes spread like this: 25
Prevention. 26
preventing the spread of germs and worms. 26
How to make a fly trap from a jar or bottle. 27
Water Borne Illnesses. 28
Containers for Storing Water. 32
Methods of Water Treatment 33
Boil the Water: 33
Chemical Treatment: 33
Three bucket Filter. 33
Bio Sand Filter. 35
Solar and UV light 35
Clear Water is Not Necessarily Clean Water. 36
Boil the Water. 37
Chemical Methods of Treatment 40
Dosage Amounts. 41
Chemical Disinfection with Halogens. 42
Iodine. 43
Iodine Crystals. 45
Halazone Tablets. 46
Chlorine Bleach. 48
Chlorine Dioxide. 51
Mixed Oxidant (MiOx) 51
Chlorine Tablets (NaDCC) 52
Other chemical disinfection additives. 52
Silver Ion tablets. 52
Hydrogen Peroxide. 54
The Four Bucket Method.. 55
Materials needed.. 56
WATER.. 57
How a Bio-Sand Filter Works. 58
The Bio-Sand Filter 63
Homemade Water Filters. 76
Glossary of Terms. 77
Credits. 86
This book is one of three which we publish on the subject of water purification and community health.
Clean Water for Life - this volume.
Purification d'leau - goes into more detail on water purification and community health for the health care worker.
Sanitation and Cleanliness for a Healthy Environment - authored by Hesperian.org, this book is designed for getting the community involved.
The United Nations University Institute for Natural Resources in Africa (UNU-INRA) supported a study that evaluated the acceptability of the bio-sand filter in rural communities in Ghana and assessed its potential for eco-business development. The findings revealed that, out of 150 rural households sampled, nearly half of the respondents lacked access to improved water supply. Similarly, a majority of the respondents (82%) did not apply any form of treatment to their drinking water. Interestingly, cultural reasons, cost and difficulty of treatment emerged as the main reasons that discouraged point-of-use water treatment. These findings call for education especially in rural communities, to promote the use of water treatment technologies like the bio-sand filter in rural households, particularly in developing continents like Africa.
Education on household water treatment and storage interventions could be intensified in community health outreach programs, especially in communities that lack access to improved drinking water.
Water is unsafe when it contains germs, worms, or toxic chemicals (for more about toxics, see Chapters 16 and 20). Germs (tiny living things, too small to see, that cause many kinds of illness) and worms, such as whipworm, hookworm, and roundworm, cause many serious illnesses.
Germs and worms live in human and animal waste (urine and feces) and can cause serious and long-lasting illnesses when: • there is not a good way to get rid of human and animal wastes. • water supplies are not protected and kept clean. • there is not enough water to wash.
Some of the illnesses they cause, such as cholera, spread quickly and can cause many deaths. Other illnesses from germs and worms can cause years of sickness and lead to other health problems such as dehydration, infections, anemia (weak blood), and malnutrition. Because the most common sign of illnesses from germs and worms is diarrhea, these illnesses are sometimes called diarrhea diseases.
Njoki lived in a village with her one-year-old son Timothy. Like the other villagers, she collected water from a tube well built many years before by a development group. Back then, when the pump would break, the development workers brought new parts to repair it. But after the development workers left, no one in the village knew how to repair the pump or where to get parts. And they had no money to buy parts anyway.
So when the pump broke, the women had to go collect water from a water hole outside the village. The water hole was also used by animals, and was contaminated with worms and germs. After drinking water from this hole, Timothy became sick with severe watery diarrhea. He grew weaker and weaker. Njoki had no money to take him to the health center many hours away. Within a few days, Timothy died.
Dehydration from diarrhea diseases is the most common cause of death for children in the world. The discussion of how people get diarrhea diseases continues on the next page.
The "But why…?" activity (see pages 7 and 12) can help to understand the different causes of Timothy's illness and death. What caused Timothy's death? Diarrhea and dehydration. But why did he have diarrhea? There were germs in the water. But why were there germs in the water? It was an unprotected water hole contaminated with germs and worms. But why did Timothy drink from an unprotected water hole? The village pump was broken. But why couldn't it be repaired?
Continue the "chain" until you run out of questions. You can also return to an earlier link and ask for more underlying causes. For example:
But why didn't Njoki make the water safe to drink? There was little firewood to boil the water and no money to disinfect it with chlorine.
The "But why…?" questions continue as people come up with reasons for Timothy's death. A chain of causes drawn on paper or on a chalkboard, or made of cardboard or flannel, can show how each cause is connected to the other causes. For each reason given, a link is added to the chain. In this way, people can understand the different causes of illness, and how these causes can be prevented.
1.A man has diarrhea outside 2.A dog eats the man's feces. 3.A child plays with the dog and gets feces on his hands. 4.The child starts to cry and his mother comforts him.he wipers his hands on her skit.
Sometimes it is easy to know where germs and worms are, especially on unclean things such as feces, rotting foods, dirty toilets, and so on. But sometimes they are in places that look clean, like clear water, or on our hands.
Germs and worms can pass from person to person through touch, and through the air with dust or when people cough or sneeze. They can spread through food and drinking water, or be carried by flies, other insects, and animals. They may also live on uncooked or poorly cooked food. Some worms can be passed by drinking, stepping into, or washing with contaminated water, or eating uncooked shellfish or plants from contaminated water. Germs and worms that cause diarrhea travel on these paths:
One way to remember the paths germs travel is they are all words beginning with the letter F : fingers, flies, feces, fields, foods, and fluids (water) 5. The mother cooks. The germs on her skirt get on her hands. She serves the food with her hands .6.The family eats the food. 7. Later, the whole family has diarrhea.
This activity helps to show how germs that cause diarrhea pass from person to person. People make drawings and put them together to form a story.
Time: 1 to 1½ hours
Materials: Small drawing paper, large drawing paper, colored pens or markers, sticky tape, sample drawings
1. Form groups of 5 to 8 people.each person draws a picture that shows something about how she thinks people get diarrhea.Each drawing should show just one part of the story of how diarrhea spreas.If a person has difficulty drawing,she can write a word instead or get help from someone else .It may help to have sample drawings to stimulate group discussion.
2.Each person shows her drawing in her small group. The other people in the group tell what they see. This is so every person understands the drawings
3. Each group puts their drawings in an order that makes a story about how germs spread. If the group sees there are drawings missing, they make new drawings to fit the story. When the drawings are in order, tape them to a larger piece of paper. Draw arrows between the drawings to make a chart that tells a story of how germs spread.
4. Each group shows its chart to the other groups. The group showing the drawings tells the story of how diarrhea passes from one person to another.
5.The whole group discusses the activity. Is every group's story the same? How are the stories different? Why? Talk about the ways diarrhea spreads. How do economic and social conditions put people at risk? What behaviors and beliefs put people at risk? What other ways do diseases spread that were not illustrated in the activity?
Most diarrhea diseases are caused by a lack of water for personal cleanliness, toilets that are not clean and safe, and contaminated water and food
The most common sign of diarrhea disease is frequent, runny or liquid feces. Other signs include fever, headache, trembling, chills, weakness, stomach and intestinal cramps, vomiting, and swollen belly. What treatment to give depends on the kind of diarrhea a person has.
These signs can help you know which diarrhea disease a person has:
• Cholera: diarrhea like rice water, intestinal pain and cramping, vomiting. • Typhoid: fever, severe intestinal pain and cramping, headache, constipation or thick diarrhea (like pea soup). • Giardia: diarrhea that looks greasy, floats, and smells bad, intestinal pain, low fever, vomiting, gas, burps sometimes smell like rotten eggs. • Bacterial dysentery (Shigella): bloody diarrhea 10 to 20 times a day, fever, severe intestinal pain and cramping. • Amebic dysentery: diarrhea 4 to 10 times a day, often with white mucus, fever, intestinal pain and cramping, and diarrhea right after eating. • Roundworm: swollen belly, weakness, large pink or white worms that may come out in feces or through the mouth and nose . • Hookworm: diarrhea, weakness, anemia, pale skin. Children with hookworm may eat dirt . • Whipworm: diarrhea, thin pink or grey worms in feces.
To learn more about treating diarrhea diseases and worm infections, see Chapters 12 and 13 in Where There Is No Doctor.
Diarrhea is best treated by giving plenty of liquids and food. In most cases, but not all, no medicine is needed. (For more information, see a health worker or a general health book such as Where There Is No Doctor.) • Amebic dysentery is best treated with medicines . • Typhoid is best treated by antibiotics because it can last for weeks and lead to death. • Cholera is best treated with rehydration drink, lots of fluids, and easyto-digest foods to replace nutrients lost through diarrhea and vomiting. Medicines may be used to prevent cholera from spreading.
If a person has bloody diarrhea, fever, or is very sick, he or she needs to go to a health center right away.
Many people die from diarrhea diseases, especially children. Most often, they die because they become dehydrated.
People of any age can become dehydrated, but serious dehydration can happen very quickly to small children and is most dangerous for them. Any child with watery diarrhea is in danger of dehydration. Give lots of liquids and take young children with signs of dehydration to a health center right away.
Thirst and dry mouth Little or no urine, or dark yellow urine Sunken and tearless eyes Sagging of the soft spot in infants Sudden weight loss Lift the skin between two fingers, like this If the skin does not fall right back to normal, the child is dehydrated. Loss of stretchiness of the skin
To prevent or treat dehydration
When a child has watery diarrhea or diarrhea and vomiting, do not wait for signs of dehydration. Act quickly. • Give lots of liquids to drink, such as a thin cereal porridge or gruel, soup, water, or rehydration drink (see next page). • Keep giving food. As soon as the sick child (or adult) can eat food, give frequent feedings of foods he likes. To babies, keep giving breast milk often — and before any other foods or drinks. • Rehydration drink helps prevent or treat dehydration. It does not cure diarrhea, but may support the sick person until the diarrhea stops.
How to make rehydration drink
Here are 2 ways of making rehydration drink. If you can, add half a cup of fruit juice, coconut water, or mashed ripe banana to either drink. These contain potassium, a mineral that helps a sick person accept more food and drink.
Give a child sips of this drink every 5 minutes, day and night, until he begins to urinate normally. A large person needs 3 or more liters a day. A small child usually needs at least 1 liter a day, or 1 glass for each watery stool. Keep giving the drink often, and in small sips. Even if the person vomits, not all of the drink will be vomited. After one day, discard the drink and make a new mixture if necessary.
(powdered rice is the best .But you can use finely ground maize,wheat flour,sorghum,or cooked and mashed potatoes) In 1 liter of clean water put half of a level teaspoon of salt. and 8 heaping teaspoons of powdered CEREAL .Boil for 5 to 7 minutes to form a liquid gruel or water porridge.Cool the drink quickly and begin to give it to the sick person.
CAUTION: Taste the drink each time before you give it to make sure that it has not spoiled. Cereal drinks can spoil within a few hours in hot weather.
. Made with sugar and salt. (you can use raw,brown or white sugar or molasses) In 1 liter of clean water put half of a level teaspoons of salt, and 8 level teaspoons of SUGAR. Mix well. CAUTION: Before adding the sugar, taste the drink and be sure it is less salty than tears.
Stop the spread of diarrhea
This activity uses the stories from the activity "How diarrhea diseases spread" (page 50) to show how to prevent diarrhea from being spread. Time: 30 minutes to 1 hour Materials: large sheet of drawing paper, colored pens or markers, sticky tape, pictures from the activity "How diarrhea diseases spread" (page 50) 1-Work in the same small groups as in the previous activity, "How diarrhea diseases spread." Each group looks at the pictures from "How diarrhea diseases spread." They then talk about how to stop the spread of disease by washing hands, using toilets, protecting food and water, and so on. Each of these actions is a barrier that blocks the spread of diarrhea. 2-When the group has agreed on what barriers will stop the spread of germs, have the group draw pictures that show the different ways to stop the spread of diarrhea diseases .3- The group then talks about how to change the story from "How diarrhea diseases spread" to "Stop the spread of diarrhea." Where do the new drawings fit in the story so that they will stop the spread of illness? The new drawings are taped in place in the old story to show how the story can change .4- Each group shows its new stories. The whole group talks about which disease barriers they use and which ones they do not use. Do all the disease barriers work all the time? Why, or why not? Why is it hard to use some of these barriers? How can the community work together to make sure that diarrhea diseases do not spread?
Guinea worm is a long, thin worm that lives under the skin and makes a painful sore on the body. The worm, which looks like a white thread, can grow to be more than 1 meter long. Guinea worm is found in parts of Africa, India, and the Middle East.
A painful swelling usually on the ankle or leg, but can develop elsewhere on the body. A few days to a week later, a blister forms which then quickly bursts open and forms a sore. This often happens when standing in water or bathing. The end of a white thread-like guinea worm can be seen poking out of the sore. The worm works its way out of the body over the next week. If the sore gets dirty and infected, or if the worm is broken by trying to pull it out, the pain and swelling spread and walking can become very difficult.
Guinea worm is spread from person to person like this:
1-An infected person with an open sore wades into a water hole. The worm pokes out of the sore and lays eggs in the water. 2. Tiny water fleas eat the worm eggs. 3. Another person drinks the water and swallows the fleas and the worm eggs in the water . 4. Some of the eggs develop slowly into worms under the skin. After a year, a sore forms when a worm breaks through the skin to lay eggs.
To treat guinea worms, see a health worker or a general health book such as Where There Is No Doctor. Also, take steps to prevent new contact with worms.
To prevent guinea worms, protect water sources (see pages 75 to 85) and filter water (see pages 94 to 97). If nobody wades or bathes in water used for drinking, the infection cannot be passed on and will eventually disappear from the area.
This infection is caused by a kind of worm that gets into the blood through the skin after wading, washing, or swimming in contaminated water. The illness can cause serious harm to the liver and kidneys, and may lead to death after months or years. Women have a greater risk of infection from blood flukes because they spend a lot of time in and around water — collecting it, washing clothes, and bathing children.
Sometimes there are no early signs. A common sign in some areas is blood in the urine or in the feces. It can also cause genital sores in women. In areas where this illness is very common, even people with only mild signs or belly pain should be tested.
1. Infected person urinates or defecates in water. 2. Urine or feces has worm eggs in it. 3 Women eggs hatch and worms go into snails. 4. Young worms leave snail and go into another person. 5. In this way, someone who washes or swims in water where and infected or defacated also becomes infected.
Treatment
Blood flukes are best treated with medicines. See a health worker about which medicines to use, or a general health book such as Where There Is No Doctor. Genital sores and blood in the urine are also signs of sexually transmitted infections (STIs). Some women will not seek treatment because they are afraid they will be blamed for having an STI. Lack of treatment can cause other serious infections and can make women infertile (unable to become pregnant).
Blood flukes are not passed directly from one person to another. For part of their life, the blood flukes must live inside a certain kind of small water snail. Community programs can be organized to kill these snails and prevent blood flukes. These programs work only if people follow the most basic preventive step: never urinate or defecate in or near water.
While germs and worms are found everywhere,there are simple steps that every person can take to help prevent illness.To stop the spread of germs and worms:
• Protect water sources and use clean water for drinking and washing. Unless you know water is safe, it is best to treat it (see pages 92 to 99) • Always wash hands after using the toilet, and before handling food. Use clean water and soap if available. If not, use clean sand or ash. Cut fingernails short. This will also help keep hands clean. • Use a toilet. This puts germs and worms out of contact with people. If there is no toilet it is best to defecate far from water sources, in a place where feces will not be touched by people or animals. Cover feces with dirt to keep flies away. • Use clean and safe methods of preparing and storing food. Wash fruits and vegetables, or cook them well before eating them. Feed left-over food scraps to animals, or put them in a compost pile or toilet. Get rid of spoiled food, keep meat and seafood separate from other foods, and make sure meat, eggs, and fish are cooked well before eating. Wash dishes, cutting surfaces, and utensils with hot water and soap after using them, and allow them to dry well in the sun if possible. • Keep animals away from household food and community water sources. • Wear shoes to prevent worms from entering through the feet. • Make fly traps and cover food to prevent flies from spreading germs. Toilets that control flies or stop them from breeding can also help (see Chapter 7).
1-Tape or glue paper to make an open cone, then fit the cone inside a plastic or glass jar or bottle. 2- Seal around the opening of the bottle so there is no space between the cone and the bottle. 3- Hang the bottle from string or wire, or attach it to a stick in the ground. 4-Put some sweet bait, like fruit or fish, just under the trap. Flies will land on the food and then fly through the cone and into the bottle. 5-To empty the trap, turn it mouth up, remove the cone, fill with water to make sure the flies are dead, and then empty it into a toilet or compost pile.
To reduce flies, hang this trap near toilets and places where food is prepared
The pathogens are the important part of water filtration. These pathogens are bacteria and protozoa which can infect our digestive systems, causing diarrhea and dehydration. Left long enough, they can cause death by dehydration. More than anything, they are the ingredient hiding in most fresh water sources, which can make us ill. So, that has to be our focus.
Untreated water may contain potentially pathogenic agents, including protozoa, bacteria, viruses, and some larvae of higher-order parasites such as liver flukes and roundworms. Chemical pollutants such as pesticides, heavy metals and synthetic organics may be present. Other components may affect taste, odor and general aesthetic qualities, including turbidity from soil or clay, color from humic acid or microscopic algae, odors from certain type of bacteria, particularly Actinomycetes which produce geosmin, and saltiness from brackish or sea water.
Common metallic contaminants such as copper and lead can be treated by increasing the pH using soda ash or lime, which precipitates such metals. Careful decanting of the clear water after settlement or the use of filtration provides acceptably low levels of metals. Water contaminated by aluminum or zinc cannot be treated in this way using a strong alkali as higher pHs re-dissolve the metal salts. Salt is difficult to remove except by reverse osmosis or distillation.
Most portable treatment processes focus on mitigating human pathogens for safety and removing particulates matter, tastes and odors. Significant pathogens commonly present in the developed world include Giardia, Cryptosporidium, Shigella, hepatitis A virus, Escherichia coli, and enterovirus. In less developed countries there may be risks from cholera and dysentery organisms and a range of tropical enteroparasites.
Giardia lamblia and Cryptosporidium spp., both of which cause diarrhea are common pathogens. In backcountry areas of the United States and Canada they are sometimes present in sufficient quantity that water treatment is justified for backpackers,[3] although this has created some controversy.[4] (See wilderness acquired diarrhea.) In Hawaii and other tropical areas, Leptospira spp. are another possible problem.[5]
Less commonly seen in developed countries are organisms such as Vibrio cholerae which causes cholera and various strains of Salmonella which cause typhoid and para-typhoid diseases. Pathogenic viruses may also be found in water. The larvae of flukes are particularly dangerous in area frequented by sheep, deer, or cattle. If such microscopic larvae are ingested, they can form potentially life-threatening cysts in the brain or liver. This risk extends to plants grown in or near water including the commonly eaten watercress.
In general, more human activity up stream (i.e. the larger the stream/river) the greater the potential for contamination from sewage effluent, surface runoff, or industrial pollutants.Groundwater pollution may occur from human activity (e.g. on-site sanitation systems or mining) or might be naturally occurring (e.g. from arsenic in some regions of India and Bangladesh). Water collected as far upstream as possible above all known or anticipated risks of pollution poses the lowest risk of contamination and is best suited to portable treatment methods.
There are several effective treatment options including chemical treatment, boiling, solar and ultra-violet light, and bio-sand filters.
+ the simplest method
- Water needs aeration after purification
- Filtering of particles still required
- Difficult to boil enough for family use
+ Quick
- Uses dangerous chemicals
- Less effective than other methods
- Leaves an after-taste of the chemicals
+ Uses readily available materials
+ Close to 100% effective
- Treated water easily contaminated
+ Easily built with common materials
+ Effectiveness increases over time
- Requires periodic maintenance
- Biological component not understood
+ Easy to build
- UV light not readily available
- Not 100% effective
Look before you drink.
Where did it come from?
Is it clear?
Does it smell?
Generally speaking things that make water undrinkable also make it misty or colored or bad smelling and the things that are toxic that don't affect the appearance of water are rare in open countryside, particularly in a mountainous area. Clean water does not smell or taste bad. If it has a metal or chemical taste, is oily, or smelly, it may be contaminated.
Sterilization of water (killing all living contaminants) is not necessary to make water safe to drink. You only need to kill the intestinal pathogens (bacteria and worms) which are both too small to be seen.
Heat kills disease-causing micro-organisms, with higher temperatures and/or duration required for some pathogens. Boiling does not remove most pollutants and does not leave any residual protection.
It's hard to purify enough water by boiling to meet a family or group's survival needs and you would still have to filter the particles;
The Health Organization (WHO) states that bringing water to a rolling boil then naturally cooling it is sufficient to kill pathogenic bacteria, viruses and protozoa.
All bacterial pathogens are quickly killed above 60 °C (140 °F), therefore, although boiling is not necessary to make the water safe to drink, the time taken to heat the water to boiling is usually sufficient to reduce bacterial concentrations to safe levels. Encysted protozoan pathogens such as Giardia lamblia may require higher temperatures to remove any risk.
The water should be held at a rolling boil for 1 minute but at high elevations the boiling point of water drops. At altitudes greater than 6,562 feet (2000 meters) boiling should continue for 3 minutes.
Boiling is not always necessary nor sometimes enough. Pasteurization where enough pathogens are killed typically occurs at 63 °C (146 °F) for 30 minutes or 72 °C (172 °F) for 15 seconds.
Certain pathogens must be heated above boiling (e.g. botulism - Clostridium botulinum requires 118 °C (244 °F), most endospores require 120 °C (248 °F), and prions even higher).
Higher temperatures may be achieved with a pressure cooker. Heat combined with ultraviolet light (UV), such as the SODIS [1] method, reduces the necessary temperature + duration.
While boiling serves to remove the pathogens, it does not remove heavy metals, pesticides and other chemicals which may be present in the water. Water which has been boiled also needs to be aerated to restore its taste. This can be done by pouring the water back and forth between two clean containers several times or allowing the water to sit open for a period of time. Generally the first method is preferred, then pour the water into a sealed container until used.
WARNING: IMPROPER USE OF CHEMICALS CAN BE VERY DANGEROUS. CHEMICALS ARE DESIGNED TO KILL MICRO-ORGANISMS WHEN USED IN VERY SMALL AMOUNTS, BUT THEY CAN ALSO CAUSE SERIOUS ILLNESS OR DEATH IF THEY ARE OVERUSED IN WATER PURIFICATION,
Chemical purification requires that you have enough of a stock of the chemical to purify the water on an on-going basis. The methods described only require ONE of these chemicals. You should NEVER mix chemicals together unless you are very sure of what you are doing. Check our website for ordering if you cannot obtain these locally.
- Iodine Crystals
- Iodine
- Halazone Tablets
- Chlorine dioxide
- Mixed oxidant (MiOx)
- Chlorine tablets (NaDCC)
Other chemical disinfection additives
- Silver ion tablets
- Hydrogen peroxide
A standard eyedropper dispenses 0.05 ml per drop, meaning there are 20 drops in 1 milliliter
A standard watter bottle holds about ½ liter or ¼ gallon.
Chemical disinfection with halogens[2], chiefly chlorine and iodine, results from oxidation of essential cellular structures and enzymes. The primary factors that determine the rate and proportion of microorganisms killed are the residual or available halogen concentration and the exposure time. Secondary factors are pathogen species, water temperature, pH, and organic contaminants. In field-water disinfection, use of concentrations of 1-16 mg/L[3] for 10-60 minutes is generally effective.
NOTE: Cryptosporidium oocysts, likely Cyclospora species, Ascaris eggs are extremely resistant to halogens and field inactivation may not be practical with chlorine and iodine.
Iodine used for water purification is commonly added to water as a solution, in crystallized form, or in tablets containing tetraglycine hydroperiodide that release 8 mg of iodine per tablet adaptation to chronic tetraglycine hydroperiodide. The iodine kills many, but not all, of the most common pathogens present in natural fresh water sources. Carrying iodine for water purification is an imperfect but lightweight solution for those in need of field purification of drinking water. Kits are available in camping stores that include an iodine pill and a second pill (vitamin C or ascorbic acid) that will remove the iodine taste from the water after it has been disinfected. The addition of vitamin C, in the form of a pill or in flavored drink powders, precipitates much of the iodine out of the solution, so it should not be added until the iodine has had sufficient time to work. This time is 30 minutes in relatively clear, warm water, but is considerably longer if the water is cloudy / mixed with organic material or cold.
NOTE: Iodine should be allowed to work at least 30 minutes to kill Giardia.
A potentially lower cost alternative to using iodine-based water purification tablets is the use of iodine crystals although there are serious risks of acute iodine toxicity if preparation and dilution are not measured with some accuracy.
An advantage of using iodine crystals is that only a small amount of iodine is dissolved from the iodine crystals at each use, giving this method of treating water a capability for treating very large volumes of water. Unlike tetraglycine hydroperiodide tablets, iodine crystals have an unlimited shelf life as long as they are not exposed to air for long periods of time or are kept under water. Iodine crystals will lose their effectiveness if exposed to air for long periods of time.
The large quantity of water that can be purified with iodine crystals at low cost makes this technique especially cost effective for point of use or emergency water purification methods intended for use longer than the shelf life of tetraglycine hydroperiodide.
NOTE This method may not be adequate in killing Giardia cysts in cold water.
Chlorine-based halazone tablets were formerly popularly used for portable water purification. Chlorine in water is more than three times more effective as a disinfectant against Escherichia coli than iodine. Halazone tablets were thus commonly used during World War II by U.S. soldiers for portable water purification, even being included in accessory packs for C-rations until 1945.
Sodium dichloroisocyanurate (NaDCC)[4] has largely displaced halazone tablets for the few remaining chlorine-based water purification tablets available today. It is compressed with effervescent salts, usually adipic acid and sodium bicarbonate, to form rapidly dissolving tablets, diluted to 10 parts per million available chlorine (ppm av.cl) when drinking water is mildly contaminated and 20ppm when visibly contaminated.
Chlorine bleach tablets give a more stable platform for disinfecting the water than liquid bleach (sodium hypochlorite) as the liquid version tends to degrade with age and give unregulated results unless assays are carried out - not practical on the spot. Still, despite chlorine-based halazone tablets falling from favor for portable water purification, chlorine-based bleach may nonetheless safely be used for short-term emergency water disinfection.
Two drops of unscented 5% bleach can be added per liter or quart of clear water, then allowed to stand covered for 30 to 60 minutes. After this treatment, the water may be left open to reduce the chlorine smell and taste.
Common bleach including calcium hypochlorite (Ca[OCl]2) and sodium hypochlorite (NaOCl) are common, well-researched, low-cost oxidizers.
The Environmental Protection Agency (EPA) recommends two drops of 8.25% sodium hypochlorite solution (regular, unscented chlorine bleach) mixed per one quart/liter of water and let stand 30 minutes.
Two drops of 5% solution also suffices. Double the amount of bleach if the water is cloudy, colored, or very cold. Afterwards, the water should have a slight chlorine odor. If not repeat the dosage and let stand for another 15 minutes before use.
If the water is clear:
• Use bleach that does not have an added scent (like lemon). If you have 5-6% household liquid chlorine bleach
IN GALLONS. Add about a teaspoon (5 or 6 drops) per gallon of water
IN METRIC - Add about 0.5 milliliters to 3 liters of water.
» For 8.25% household liquid chlorine bleach - add a little less than 1/8 teaspoon (6 drops or about 0.5 milliliters) to 1 gallon (16 cups of water).
• Mix well and wait at least 30 minutes or more before using.
If the water is cloudy:
• Use bleach that does not have an added scent (like lemon).
» For 5-6% household liquid chlorine bleach - add a little less than ¼ teaspoon (16 drops or about 1 milliliters) of household liquid bleach to 1 gallon (16 cups) of water.
» For 8.25% household liquid chlorine bleach - add 12 drops (or about 1 milliliter) to each 1 gallon (16 cups or water).
Remember that containers may need to be cleaned and sanitized before using them to store safe water:
1. Clean the container and rinse it out.
2. Use bleach that does not have an added scent (like lemon).
3. Add 1 teaspoon (64 drops or 5 milliliters) of household liquid bleach to 1 quart
(32oz, 4 cups, or about 1 liter) of water.
4. Pour this into a clean storage container, cover tightly, and shake well. Make sure the solution coats the entire inside of the container.
5. Let sit at least 30 seconds, and then pour out solution.
6. Let air dry OR rinse with clean water that has already been made safe, if available.
7. Pour clean water into the sanitized container and cover with a tight lid.
■ Never mix bleach with ammonia or other cleaners.
■ Open windows and doors to get fresh air when you use bleach.
NOTE: Neither chlorine (e.g., bleach) nor iodine alone is considered completely effective against Cryptosporidium, although they are partially effective against Giardia. Chlorine is considered slightly better against Giardia.
A more complete field solution that includes chemical disinfectants is to first filter the water, using a 0.2 µm ceramic cartridge pumped filter, followed by treatment with iodine or chlorine, thereby filtering out cryptosporidium, Giardia, and most bacteria, along with the larger viruses, while also using chemical disinfectant to address smaller viruses and bacteria that the filter cannot remove. This combination is also potentially more effective in some cases than even using portable electronic disinfection based on UV treatment.
Chlorine dioxide can come from tablets or be created by mixing two chemicals together. It is more effective than iodine or chlorine against giardia, and although it has only low to moderate effectiveness against cryptosporidium, iodine and chlorine are ineffective against this protozoan. The cost of chlorine dioxide treatment is higher than the cost of iodine treatment.
A simple brine {salt + water} solution in an electrolytic reaction produces a powerful mixed oxidant disinfectant (mostly chlorine in the form of hypochlorous acid (HOCl) and some peroxide, ozone, chlorine dioxide).
This method requires equipment which is beyond the scope of this book. It is an ideal setup for a community based water purification system. See our website for details and videos on implementation.
Sodium dichloroisocyanurate or Troclosene Sodium more commonly shortened as NaDCC, is a form of chlorine used for disinfection. It is used by all major NGO's[5] such as UNICEF[6] to treat water in emergencies, and widely by social marketing organizations for household water treatment where household sources of water may not be safe.
NaDCC tablets are available in a range of concentrations to treat differing volumes of water to give the World Health Organization's recommended 5ppm available chlorine. They are effervescent tablets allowing the tablet to dissolve in a matter of minutes.
An alternative to iodine-based are silver ion/chlorine dioxide-based tablets or droplets. These solutions may disinfect water more effectively than iodine-based techniques while leaving hardly any noticeable taste. Silver ion/chlorine dioxide-based disinfecting agents will kill Cryptosporidium and Giardia, if utilized correctly. The primary disadvantage of silver ion/chlorine dioxide-based techniques is the long purification times (generally 30 minutes to 4 hours, depending on the formulation used). Another concern is the possible deposition and accumulation of silver compounds in various body tissues leading to a rare condition called argyria that results in a permanent, disfiguring, bluish-gray pigmentation of the skin, eyes, and mucous membranes.
In ozone water disinfection, microbes are destroyed by ozone gas (O3) provided by an ozone generator. Common in Europe, ozone gas is now becoming widely adopted in the United States. It is emerging across a wide array of industries; from municipal water treatment plants, to food processing plants, to healthcare organizations. It is being adopted due to its ability to sanitize water and surfaces without wasting water, and because there are no by-products. When its job is done, ozone gas quickly degrades into oxygen. Ozone is more effective than chlorine in destroying viruses and bacteria.
In 1990, the Organic Foods Production Act (OFPA) identified aqueous ozone as a substance that is allowed for use in organic crop and livestock production. In 1997, it was approved by the FDA as an antimicrobial agent for use on food. In 2002, the FDA approved ozone for use on food contact areas and directly on food with its Generally Regarded as Safe ("GRAS") designation.
Ozone is most commonly created by a process called "corona discharge", which causes oxygen molecules (O2) to temporarily re-combine into ozone (O3). This gas is very unstable, and the 3rd oxygen molecule reacts with pathogens by penetrating the cell walls of bacteria and viruses. This destroys the organisms.
Ozone is effective against pollutants for the same reason; it will react with long-chain carbon (organic) molecules, and break them down into less complex (and typically less harmful) molecules through oxidation.
Advances in ozone generation techniques, coupled with filtration, make this a viable new portable water purification method.
One recent study has found that the wild Salmonella which would reproduce quickly during subsequent dark storage of solar-disinfected water could be controlled by the addition of just 10 parts per million of hydrogen peroxide.
This is a proven and recommended method for purifying water that can provide for a household on an on-going basis. It is used and recommended by the American Red Cross and often referred to as a bio-purification method. It has little cost and can be implemented with readily available materials.
The water filter consists of four five gallon buckets that work to filter successively smaller particles out of the water, until you're left with relatively clean and safe drinking water. This is a relatively low-cost solution and in most circumstances preferable over having to boil water.
· A drill with 1″ and 2″ hole saws
· Four 5-gallon buckets
· Screening (the type used to replace a torn window screen)
· Three ceramic wall tiles (the type you use for a bathroom)
· Scissors
· Something to use for a stand
· Sand to fill one of the buckets within 4 inches of the top. Coarse sand is best with a combination of very small and pebble size grains.
· Pea gravel to fill one of the buckets within 4 inches of the top. Granite or other hard stone is best. Limestone and other soft stone should be avoided
· Activated charcoal or carbon (volume should be roughly equal to the sand and gravel)
· Epoxy glue
GRAVEL
SAND
CHARCOAL
PURE
WATER
A fourth bucket or other container that can be sealed or covered with a cloth should be used to hold the purified water. Care should be taken to not allow this water to become recontaminated.
Step one: Drill a one inch hole at the bottom of three of the four buckets Step two: Use a two inch hole saw and drill a hole in the lids of two of the buckets. Do not drill a hole in the lid for the top bucket, The holes do not need to sit in the same places as the 1 inch holes.
Step three: Take the screening and cut out a couple of three inch squares of the screening material for each of the buckets.
To give it added strength, use more than one. Use the epoxy to put these squares in place on the inside of the buckets, so that they cover the one inch holes. You may need to use something to hold the scrit eening down, while the epoxy is curing.
Step four: Put the ceramic tiles on the screening, shiny side up. Use a small amount of epoxy in the corners to fix the tiles in place.
Step five: Prepare the filter medium. If the activated charcoal is not crushed,, crush until you have very small pieces of up to a few millimeters in size.
Clean your filter medium. Put it in a bucket full of water and watch whether the water becomes cloudy. Keep rinsing the filter material until the water ceases to get cloudy. Do this for the gravel, the sand and the activated charcoal. When one of the filter mediums is clean, put it in a bucket, until you have all the filter mediums in a separate bucket.
Step six: Put the lids on the charcoal and sand buckets. The charcoal bucket should stand at the bottom, on top of something so the hole at the bottom isn't covered, the sand bucket on top of it and the gravel bucket goes on top of the sand bucket.
Step seven: With your buckets in place, start pouring water onto the top gravel bucket, using your fourth bucket. At first, the water will come out cloudy. This is simply dirt that you didn't manage to remove from your filter medium right away. Over time however, clean water will start to come out, that you can drink.
Activated charcoal is an amazing material. It is charcoal or carbon, in which the pores have been opened, expanding the surface area A reasonably good activated charcoal (such as the powder pictured here) will have 125 acres of surface area per pound. That's what makes it so effective. The large surface area traps the pathogens, preventing them from passing through.
Where do I get activated charcoal?
Activated charcoal can be purchased commercially, but it can also be made.
The easiest way to make it is to treat charcoal with a strong base. Common household salt is ideal but lemon juice can also be used. This will cause the pores in the charcoal to open up. The wood is usually impregnated, by soaking the wood in it, before burning. Then, as the wood burns, the pores are opened. Most any hardwood wood can be used, but bamboo and coconut shells makes especially good sources.
If you are beginning your process with charcoal which you already have, soak the charcoal in saltwater which is 1/3 salt and 2/3 water. The charcoal should be allowed to soak for 6 to 8 hours. If you are beginning to make charcoal with wood, soak the wood before making the charcoal.
Once the charcoal has soaked, place in a pot and allow it to cook on a very hot fire until most of the liquid has evaporated and you are left with a more dense charcoal material which is mostly carbon.
Use a mortar and pistle to pulverize the charcoal into a very fine powder, then rinse it to remove as much of the salt as you can.
Add more saltwater to the charcoal powder until you have the consistency of paste. Return this to the fire in a steel or glass container and allow it to boil dry. This step actually activates the charcoal, opening up the pores making it effective.
Once this process is completed, rinse the activated charcoal again with clean water. It is now ready to use as a filtering material.
This chapter describes a system which is essentially the same as the 4 bucket method described in the previous section but designed for more permanent use. [8]
Bio-sand filters (BSFs) are the best low-cost systems for point-of-use water treatment. Sand filtration has been used for centuries and most closely mirrors the way water is purified in nature. It is simply a concrete container, enclosing layers of sand and gravel whose purpose is to eliminate sediments, pathogens and other impurities from the water. It is in use in homes in over 70 countries around the world.
While sand has been used for centuries to purify water, the sand preparation method and active biological layer of BSFs are uniquely effective at filtering heavily contaminated water. The process removes virtually all parasites and almost all bacteria and viruses. Because filters must be made locally, they offer other benefits to the community such as employment opportunities, business growth for local suppliers who can provide raw materials for the filters as well as providing a source of community pride.
In conjunction with the introduction of bio-sand filters to communities, the filter has been tested by various government, research, and health institutions, as well as by non-governmental agencies.
Overall, these studies have shown that the BioSand filter removes:
• Up to 98% of fecal coliform
• 100% of protozoa and helminths
• up to 67% of iron and manganese
• most suspended sediments
• Removes up to 98.5% bacteria, 99.9% parasites
• Removes turbidity, some iron, manganese
• Quality of water improves with time
• Costs US $85.
• High flow rate - 24 liters/hour
• No on-going costs - no replaceable parts
• Durable & robust- lasts forever
• Fabricated from local materials
• Opportunity for local businesses
• Water tastes & looks good
• Easy to maintain
Not only will treatment options like the bio-sand filter be beneficial to rural communities, but urban areas, especially areas that lack potable drinking water, can also consider using the bio-sand technology to treat water before drinking.
While there are many water purification methods, nearly all of them rely on a source of power, complex manufacturing processes, frequent maintenance or replacement, or a continuous supply of chemicals.
Bio-sand filters can easily be made out of readily available materials. They essentially duplicate the same process that a water treatment plant uses to purify water, but on a much smaller scale.
A bio-sand filter consists of a concrete or plastic container, filled with specially selected and prepared sand and gravel to help in removing unwanted substances from water.
This multi-stage process removes dissolved and suspended solids, as well as almost all water borne pathogens.
· have no moving parts or mechanical or electrical components and require no fuel or electricity
· are significantly less expensive than other options
· require very simple maintenance
· are constructed from materials available in almost every community
· are virtually indestructible and too heavy to steal.
A single bio-sand filter can purify up to 60-80 liters of water per day, enough to supply the needs for a household of 10 or more people. For all these reasons, BSFs are extremely well-suited to purify water in rural regions of the developing world.
The Bio-sand filter is an innovation on traditional slow sand water filters, having been specifically designed for intermittent use.
Operating the filter is very simple: remove the lid, pour a bucket of water into the filter, and immediately collect the treated water in a container. Because of its smaller surface area, the filter can produce up to 36 liters/hour
When water is poured into the top of the filter, a diffuser plate placed above the sand bed dissipates the initial force of the water. Traveling slowly through the sand bed, the water then passes through several layers of gravel and collects in a pipe at the base of the filter. At this point, the water is propelled through plastic piping encased in the concrete exterior, and out of the filter, ready for drinking.
The removal of pathogens occurs in the BioSand filter due to a combination of biological and mechanical processes.
When water is poured into the top of the filter, the organic material it is carrying is trapped at the surface of the fine sand, forming a biological layer or ‘schmutzdecke' [9].
Over a period of one to three weeks, micro-organisms colonize the schmutzdecke, where organic food and oxygen derived from the water abounds. Biological processes remove pathogens and other contaminants in this filter:
• Predation
• Natural death
• Adsorption
• Mechanical trapping
The schmutzdecke micro-organisms consume bacteria and other pathogens found in the water, thereby providing highly effective water treatment. It mirrors the process that is used in nature to purify water.
Pathogens are removed due to food scarcity and less than optimal temperatures.
Viruses are absorbed (become attached) to the sand grains. Once attached, they are metabolized by the cells or are inactivated by antiviral chemicals produced by the organisms in the filter. Certain organic compounds are also adsorbed to the sand and thus removed from the water.
Sediments, cysts and worms are removed from the water by becoming trapped in the spaces between the sand grains. When precipitated, the filter can remove some inorganic compounds and metals from the water.
Slow sand filters have been proven to almost entirely remove the disease-causing organisms found in water in both laboratory and field tests.
Made from concrete, sand, and gravel, BSFs consist of a chimney-like container about 1 meter tall with a 20 cm square opening. The container is filled with several centimetres of coarse and fine gravel followed by carefully prepared fine sand. When the filter is filled with water the sand and gravel layers are fully submerged. In two to four weeks, a layer of microorganisms (the ‘biological layer') grows on the surface. At this point the filter is ready for use.
BSFs purify contaminated water by several mechanisms. When dirty water from a contaminated stream or well is poured into the BSF:
· Dirt and larger particles are trapped at the top of the sand layer the biological layer ‘eats' a significant portion of the parasites and other microorganisms within the water fine sand traps remaining bacteria where they suffocate due to lack of oxygen.
· Gravity then pulls the purified water to the gravel layer at the bottom and up a standpipe to a spigot. Water that exits the filter is clear, clean and safe (and even cool!).
The Centre for Affordable Water and Sanitation Technology www.cawst.org (CAWST) in Calgary, Canada, provides training and resources to organizations working to build Bio-sand Filters and to provide clean water in developing countries.
The following article explains how to build a bio-sand water filter.
A bio-sand filter is a three stage filter, allowing each stage to provide a finer level of filtration.
In solar water disinfection (SODIS), microbes are destroyed by temperature and UVA radiation provided by the sun. Water is placed in a transparent plastic PET bottle[10] or plastic bag, oxygenated by shaking partially filled capped bottles prior to filling the bottles all the way, and left in the sun for 6-24 hours atop a reflective surface.
SODIS METHOD
The SODIS method is ideal for treating water for drinking in developing countries. All it requires is sunlight and PET bottles.
Clear PET bottles are filled with the water and set out in the sun for 6 hours. The UV-A rays in sunlight kill germs such as viruses, bacteria and parasites (giardia and cryptosporidia). The method also works when air and water temperatures are low.
People can use the SODIS method to treat their drinking water themselves. The method is very simple and its application is safe. It is particularly suitable for treating relatively small quantities of drinking water.
Research
Many scientific studies confirmed the effectiveness of the SODIS method. It kills germs in water very efficiently. The method has even been shown to improve the health of the population. Research into training strategies gave insight about which communication methods are most suitable. It has also been proven that the use of PET bottles in the SODIS method is harmless.
International recognition
The World Health Organisation (WHO), UNICEF, and the Red Cross therefore recommend the SODIS method as a way to treat drinking water in developing countries.
"Solar disinfection is an example of another measure with proven health impact that requires little capital investment on the part of end-users, and is thus appropriate for the very poor." WHO, 2007
"UNICEF promotes a variety of treatment methods such as user-friendly filtration, simple solar water disinfection (SODIS) and home chlorination. These are all low-cost, effective and manageable at the household level." UNICEF, 2009
Red Cross Prize, 2006: "The jury considers SODIS an impressive way of contributing by the simplest means to making water supplies better and safer, thereby reducing diarrhoea and other diseases like it, and mortality in developing countries." Red Cross, 2006
https://www.sodis.ch/methode/index_EN
Solar Distillation
Solar distillation relies on sunlight to warm and evaporate the water to be purified which then condenses and trickles into a container. In theory, a solar (condensation) still removes all pathogens, salts, metals, and most chemicals but in field practice the lack of clean components, easy contact with dirt, improvised construction, and disturbances result in cleaner, yet contaminated water.
Reverse Osmosis is a system which relies on a ceramic filter with very fine holes about the 1/1000th of a human hair. Water is forced through the system under pressure. The filter removes everything except the smallest molecules (hydrogen and oxygen) resulting in ultra-purified water.
The downside of Reverse Osmosis is that it removes EVERYTHING including trace minerals such as Iron, Magnesium, and Potassium which the body needs and generally gets from drinking water. The special filters needed and the power needed to run the pumps make this a less than ideal method of treatment. Many cities aroiund the world use this method however, augmented by chemical treatment and UV light to assure purification.
References
1. ^ Problem Organisms in Water: Identification and Treatment, 3rd Ed. (M7). Amewrican Waterworks Associan. 2004. 2. ^ Geldreich E. Drinking water microbiology—new directions toward water quality enhancement. Int J Food Microbiol 1989;9:295-312. 3. ^ Boulware DR, Forgey WW, Martin WJ (2003). "Medical risks of wilderness hiking". The American Journal of Medicine. 114 (4): 288-93. doi:10.1016/S0002-9343(02)01494-8. PMID 12681456. 4. ^ Welch TP (2000). "Risk of giardiasis from consumption of wilderness water in North America: a systematic review of epidemiologic data". International Journal of Infectious Diseases. 4 (2): 100-3. doi:10.1016/S1201-9712(00)90102-4. PMID 10737847. 5. ^ "What is Leptospirosis?" (PDF). Hawaii State Department of Health. September 2006. Retrieved 26 November 2009. 6. ^ Jump up to:a b Ericsson, Charles D.; Steffen, Robert; Backer, Howard (1 February 2002). "Water Disinfection for International and Wilderness Travelers". Clinical Infectious Diseases. 34(3): 355-364. doi:10.1086/324747. PMID 11774083. Retrieved 3 June 2018 - via cid.oxfordjournals.org. 7. ^ Clayton D.B:date=1989. Water pollution at Lowermoore North Cornwall. Lowermoore incident health advisory committee, Cornwall District Health Authority. p. 22. 8. ^ http://www.who.int/water_sanitation_health/dwq/Boiling_water_01_15.pdf?ua=1&ua=1 9. ^ Jump up to:a b c d "A Guide to Drinking Water Treatment and Sanitation for Backcountry & Travel Use". Centers for Disease Control and Prevention. 10 April 2009. Retrieved 19 March2018. 10. ^ Backer, H. Water Disinfection for International and Wilderness Traveler. Clinical Infectious Diseases. (2002) 34 (3): 355-364. Available from: http://cid.oxfordjournals.org/content/34/3/355.full 11.^ Lawley R (1 January 2013). "Cryptosporidium". Food Safety Watch. 12.^http://www.bellarmine.edu/faculty/dobbins/Secret%20Readings/Lecture%20Notes%20202/Chapter%2011WO.pdf 13. ^ Hoff J. Inactivation of microbial agents by chemical disinfectants. Cincinnati: US Environmental Protection Agency; 1986. EPA/600/2-86/067. 14. ^ LeMar HJ, Georgitis WJ, McDermott MT (1995). "Thyroid adaptation to chronic tetraglycine hydroperiodide water purification tablet use". Journal of Clinical Endocrinology and Metabolism. 80 (1):220-3. doi:10.1210/jcem.80.1.7829615. PMID 7829615. 15. ^ "EQUIPPED TO SURVIVE (tm) - Repackaging Potable Aqua". www.equipped.com. Retrieved 3 June 2018. 16. ^ Kahn FH, Visscher BR (1975). "Water Disinfection in the Wilderness -- a simple, effective method of iodination". Western Journal of Medicine. 122 (5): 450-3. PMC 1129772. PMID 165639. 17. ^ Zemlyn S, Wilson WW, Hellweg PA (1981). "A caution on iodine water purification". Western Journal of Medicine. 135 (2): 166-7. PMC 1273058. PMID 7281653. 18. ^ Jarroll EL Jr.; Bingham AK; Meyer EA (1980). "Inability of an iodination method to destroy completely Giardia cysts in cold water". Western Journal of Medicine. 132 (6): 567-9. PMC 1272173. PMID 7405206. 19. ^ Koski TA, Stuart LS, Ortenzio LF (1966). "Comparison of Chlorine, Bromine, and Iodine as Disinfectants for Swimming Pool Water". Applied Microbiology. 14 (2): 276-9. PMC 546668. PMID 4959984. 20. ^ EPA, OW, US (2013-02-20). "Ground Water and Drinking Water - US EPA". US EPA. Retrieved 3 June 2018. 21.^[http://phc.amedd.army.mil/PHC%20Resource%20Library/Electrochemically%20Generated%20Oxidant%20Disinfection%20in%20the%20Use%20of%20Individual%20Water%20Purification%20Devices.pdf Electrochemcially Generated Oxidant Disinfection In the Use of Individual Water Purification Devices, US Army Public Health Command, Prepared by: Steven H. Clarke, Environmental Engineer, March 2006, updated January 2011] 22. ^ "UNICEF - Progress on Drinking Water and Sanitation" (PDF). 23. ^ "Water Purification Tablets". 24. ^ "WHO - Guidelines for drinking-water quality, fourth edition". 25. ^ Sciacca F, Rengifo-Herrera JA, Wéthé J, Pulgarin C (2010-01-08). "Dramatic enhancement of solar disinfection (SODIS) of wild Salmonella sp. in PET bottles by H(2)O(2) addition on natural water of Burkina Faso containing dissolved iron". Chemosphere (epub ahead of print)|format= requires |url= (help). 78 (9): 1186-91. doi:10.1016/j.chemosphere.2009.12.001. PMID 20060566. 26. ^ USEPA, Ultraviolet Disinfection Guidance Manual for the final LT2ESWTR, Nov 2006 27. ^ "National Primary Drinking Water Regulations: Long Term 2 Enhanced Surface Water Treatment Rule". Federal Register. 71 (3): 783. 5 Jan 2006. Retrieved 17 Apr 2010. 28. ^ Mofidi AA, Meyer EA, Wallis PM, Chou CL, Meyer BP, Ramalinham S, Coffey BM (2002). "The effect of UV light on the inactivation of Giardia lamblia and Giardia muris cysts as determined by animal infectivity assay (P-2951-01)". Water Research. 36 (8): 2098-108. doi:10.1016/S0043-1354(01)00412-2. PMID 12092585. 29. ^ Campbell AT, Wallis P (2002). "The effect of UV irradiation on human-derived Giardia lamblia cysts". Water Research. 36 (4): 963-9. doi:10.1016/S0043-1354(01)00309-8. PMID 11848367. 30. ^ Linden KG, Shin GA, Faubert G, Cairns W, Sobsey MD (2002). "UV disinfection of Giardia lamblia cysts in water". Environmental Science and Technology. 36 (11): 2519-22. doi:10.1021/es0113403. PMID 12075814. 31. ^ Qiu X, Sundin GW, Chai B, Tiedje JM (November 2004). "Survival of Shewanella oneidensis MR-1 after UV Radiation Exposure". Applied and Environmental Microbiology. 70 (11): 6435-43. doi:10.1128/AEM.70.11.6435-6443.2004. PMC 525172. PMID 15528503. https://en.wikipedia.org/wiki/Water_purification https://en.wikipedia.org/wiki/Portable_water_purification https://sustainabilityactive.com/2018/01/bio-sand-filter-household-water-treatment-option-africa/https://www.bopomavillages.org/what-we-do/clean-water/bio-sand-filter/
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[1] "Solar water disinfection" - SODIS for short - thus offers a solution for preventing diarrhoea, one of the most common causes of death among people in developing countries. See page ??
[2] One of a group of chemical elements that includes chlorine, fluorine, and iodine. When placed in water they combine with the hydrogen molecules to form a salt compound.
[3] Conversion of milligrams to millileters depends on the density of the liquid, but for our discussion if the chemical is in liquid state and has the consistency of water, the relationship is 1 to 1. (1 milligram = 1 millileter). See https://vodoprovod.blogspot.com/p/weight-g-density-gcm3-volume-liters.html
[4] The Centers for Disease Control & Prevention (CDC) and Population Services International (PSI) promote a similar product (a 0.5% - 1.5% sodium hypochlorite solution) as part of their Safe Water System (SWS) strategy. The product is sold in developing countries under local brand names specifically for the purpose of disinfecting drinking water.
[5] Non Governmental Organizations
[6] Unted Nations International Emergency Fund
[7] Adapted from http://cleanwaterforhaiti.org/programs/how-does-the-filter-work/
[8] Development of this system is largely the work of Dr. David Manz working at the University of Cal-gary. (https://manzwaterinfo.ca/)
[9] German, "dirt cover" or dirty skin, sometimes wrongly spelled schmutzedecke) is a hypogeal biological layer formed on the surface of a slow sand filter.
[10] Typically, the plastic bottles used to hold potable water and other drinks are made from polyethylene terephthalate (PET)