Stichting Connect I nternational
Factsheet
3.5
Clean and Safe Water
Water treatment: other
methods
Information for VAG Leaders
Preparations:
- The VAG leader should read through the factsheet and make sure that he/ she
understands the content.
- This is a continuation of Fact Sheet Series Clean and Safe Water
- In this factsheet, the members will learn more possibilities of making water Clean
and safe.
- in the last fact sheet on filtering was discussed as a method to make the water
clean and safe
- In this fact sheet Boiling water, use of chlorine, Solar Disinfection (SodiS) and use
of Lemon or lime will be discussed as methods of treating water to make it safe
for drinking.
- Bring 5 pens and sheets of paper, an empty plastic bottle, household bleach, a
container for 1 L of water, some mother solution and a lemon/ lime.
Why is it important to treat (i.e. disinfect) our drinking water?
Contaminated water contains germs (tiny organisms) that can make people sick.
Water from protected water points, such as boreholes or protected wells, could be
safe to drink, but you are only sure if the water has been tested. If not the water
should be treated before drinking. Water from open water sources, such as rivers,
pools, wells, etc. should always be treated before drinking, as there is a possibility
that it has been contaminated. Disinfecting water kills germs. If done correctly,
disinfection makes water completely safe to drink.
What are the most effective methods for treating our water?
Discuss the different methods of treating water with the community.
Stichting Connect I nternational
Factsheet
3.5
1. Boiling
Do people in our community treat their drinking water by boiling it? Is
it a good method, and why?
Let the members discuss.
How long should we boil our drinking water before it is safe for
drinking?
Let the members come up with answers first. Then explain:
- Boiling water is very effective in killing germs. If you boil water for 1 minute it will
be safe. Bring water to a rapid, rolling boil. Once it starts boiling, let it boil for 1 full
minute before taking the pot off to cool.
- After the water has cooled off, pour it into a bottle and shake it strongly. This will
add air to the water and will improve the taste.
- The disadvantage of boiling water is that you need a lot of firewood, fuel or
electricity to boil enough drinking water for the whole family. It also takes quite
some time to boil the water, and it takes a long time to let it cool down. So it
cannot be used straight away.
2. Clorine
What is chlorine and how can it be used for treating drinking
water?
Chlorine is a mineral that comes in different forms, for instance in
bleaching powder and household liquid bleach. If added to water, it
kills most germs and other tiny organisms and it dissolves in the
process. It's cheap and easy to use.
Do people in our community use chlorine to treat drinking water? Is it a good
method, and why?
Let the members discuss. If chlorine treatment is uncommon, you need to
demonstrate the method for 1 L of water. You need to prepare some mother solution
before the meeting, to save time. Go through the following:
Using chlorine:
1. Be mindful of how much chlorine to add to the water.
The amount of chlorine needed to disinfect water depends on how contaminated the
water is (how many and what kinds of germs it contains). The more germs you have,
the more chlorine you need to get rid of them. It is important to add enough chlorine
so that some of it is still left in the water after the germs are killed. The chlorine that is
left is called free chlorine. This will kill any new germs that enter the water. If the
water has free chlorine in it, it will smell and taste just slightly of chlorine. This tells
you it is safe to drink. If it has too much, the smell and taste will be strong and
unpleasant.
2. Get rid of solid matter in the water.
If there is a lot of solid matter in the water the chlorine will be less effective in killing
germs. To ensure that chlorine is most effective, you either filter the water or let the
water settle so solid matter sinks to the bottom. Pour the clear water off into a clean
container before you add chlorine.
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Factsheet
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3. Make the mother solution.
Household bleach is the most common form of chlorine. Household bleach may
contain different amounts of chlorine, so you need to determine how much you need
of it. The easiest way to do this is to first make a mother solution and then add this
solution to the water you want to disinfect. To prepare the mother solution:
- Add 1 cup (e.g. teacup) of bleach to a clean, empty bottle.
- Fill the bottle with clean water.
- Shake the bottle for 30 seconds.
- Let it sit for 30 minutes.
- Your mother solution is ready.
4. Disinfect the water.
Add the following amounts of the
mother solution to the water and
wait at least 30 minutes before
drinking it:
- For 1 L: 3 drops of chlorine
(demonstrate and use the water
in the exercise later on);
- For 4 L: 12 drops of chlorine;
- For 20 L: 1 teaspoon of chlorine;
- If the water is cloudy, you need
twice as much of the mother
solution.
The difficulty with chlorine is that if too little is used it will not kill germs or make the
water safe. If too much is used, the water will taste bad and people may not want to
drink it. Therefore, chlorine treatment is a very precise method that you have to
practise carefully.
3. Solar disinfection (SODIS)
What is meant by solar disinfection, or SODIS?
Solar disinfection is a very effective, easy and
cheap way to treat water with sunlight and a bottle.
Contaminated water is filled into transparent plastic bottles and exposed to full
sunlight for 6 hours. The sunlight destroys the germs in the water.
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Factsheet
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Show the SODIS illustration and indicate the separate steps during your explanation.
SODIS works as follows:
1. Take a clean and transparent plastic bottle.
2. Fill the bottle with water up to ¾ and close the lid tight.
3. Shake the bottle for 20 seconds, and then fill the bottle to the top. The air bubbles
will help to disinfect the water faster.
4. Place the bottle in an open place, where it is exposed to full sunlight (e.g. the roof
of your house).
5. Leave the bottle in the sun for at least 6 hours, or 2 days if it is cloudy.
6. Store the water in the same bottle and drink directly from it, or from a clean cup.
This will prevent possible contamination from hands or other vessels.
7. If the water is very dirty, it is best to filter or settle the water first, before starting
SODIS.
Do people in our community use SODIS to treat drinking water? Is it a good
method, and why?
Let the members discuss; don't forget the practicalities of this method (for instance,
the availability of bottles).
4. Lime or lemon juice
Do people in our community use lime or lemon juice to treat
drinking water? Is it a good method, and why?
Let the members discuss; don't forget the practicalities of this
method (for instance, the availability of limes and lemons!).
How to use lime or lemon juice:
Adding the juice of 1 lime or lemon to 1 litre of drinking water will kill most cholera
and other germs. Using lime or lemon juice does not make water completely safe, but
it's better than no treatment in areas where cholera is a threat. Adding lime or lemon
juice to water before using solar disinfection (SODIS) will improve its effectiveness.
Exercise: comparing the methods.
Divide the VAG into 5 groups, and let each group discuss the advantages and
disadvantages of one of the methods for treating drinking water. They may write
these down if they want (distribute the pens and paper).
Group 1 - filtering the water
Group 2 - boiling water
Group 3 - chlorine
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Factsheet
3.5
Group 4 - solar disinfection (SODIS)
Group 5 - lime or lemon juice.
After 10-15 minutes, let the groups present their comments. After the presentations,
have a general discussion on what the members think is the best way to disinfect
their drinking water, if there is one. Then ask whether the knowledge they have
gained about the treatment of water, should lead to action points, for example
informing the rest of the community, or a communitywide experiment with different
methods.
If 30 minutes have passed since the chlorine demonstration, the chlorinated water
may be tested by the members.
Concluding notes.
- Ask if there are any further questions.
- Remind the members on the action points they have decided on.
- Agree on the date, time, place and topic of the next meeting.
- Close the meeting.