Ministry of health and sanitation District Health Management Team Chlorination of wells and Disinfection of Latrines

Transcription

1 Ministry of health and sanitation District Health Management Team Chlorination of wells and Disinfection of Latrines Manual for Community Health Promoters, NGO workers and qualified personnel. Freetown, Sierra Leone February 2008

2 Chlorination of wells and disinfection of latrines ACF / DHMT 2 Introduction The Ministry of Health and Sanitation carries out health related activities through the District Health Management Teams (DHMT). The DHMT-Western Area has been working in close partnership with Action Contre La Faim on domestic water management diagnosis related to cholera prevention activities in Freetown urban. Over the past months, ACF and the DHMT have successfully mapped out all the water points within the Freetown Urban Area. As a result of this, there is a need to carry out massive community sensitisation and disinfection of water points and latrines. It is with this background that this manual was developed. The objective of this manual is to teach Community Health Promoters to appropriately chlorinate wells and disinfect latrines in their various localities. Chlorination of water points and disinfection of latrines are major preventive actives in the control of cholera. Doctor Amara Jambai, Ministry of Health District Health Management Team

3 Chlorination of wells and disinfection of latrines ACF / DHMT 3 1. Did you know that - The Origin of Cholera and other Diarrhoea is EXCRETA (human and animal faeces) - This is because ONE single gram of human faeces can contain up to: Remember: Infectious Diarrhoea (running stomach, dysentery, cholera, typhoid ) are caused by infectious agents like: VIRUS BACTERIA PARASITES These agents get into human system via the mouth and are passed out in faeces. This is called contamination. In fact, contamination can be avoided easily. Let us see how!

4 Chlorination of wells and disinfection of latrines ACF / DHMT 4 2. What is Cholera? Cholera is a severe infection of the intestine. It is caused by a bacterium called Vibrio Cholera. This bacterium produces a strong toxin within the intestine, immediately after contamination. This toxin will spread quickly on the lining of the intestine, preventing its functions: The intestine will not be able to digest the food intake; instead it will produce massive liquid stools (diarrhoea). If no treatment is administered quickly, the patient will pass too much water in the stools, and dehydration shock will occur within a few hours, eventually causing death. This is one picture of the bacterium called Vibrio responsible for Cholera. The Vibrio of cholera can be transmitted in food, water or direct contact with a contaminated person. This is why it is a highly contagious disease that can spread quickly in the general population. The germ of cholera (and any other pathogen agent) can be destroyed by: - Cooking the food: the heat kills it. - Boiling the water one will drink: again, the heat will kill it. - Chemical action of disinfections: the chemical reaction will kill it in water (shock chlorination). If you use treated water (with chlorine) you can also kill it by washing hands, clothes, floor, latrines, etc. (contact chlorination).

5 Chlorination of wells and disinfection of latrines ACF / DHMT 5 3. What are chlorination and disinfection? Some water sources contain disease-causing organisms, which need to be removed or killed before the water is safe to drink. Such water is called contaminated and is not safe for drinking. The action to kill the organisms with chlorine is named chlorination. If carefully undertaken and monitored, chlorination is an effective means of removing such organisms. Chlorine is the most widely used disinfectant, and one of the most easy to use. Chlorine purifies the water by damaging or destroying the cell structure of bacterial pollutants, thereby killing them. The most common sources of chlorine are the High Test Hypochlorite (HTH), which is a white powder containing 65 or 70 % of active chlorine and the bleach, a transparent liquid containing from 2 to 10 % of chlorine. Bleach can be purchased in shops and supermarkets, it costs around Leones per gallon. It is used for laundry and other household s applications. When you buy bleach, check out the label for the concentration of active chlorine, indicated in %. If, for any reason, one cannot use HTH or bleach to treat the water, the only other option is to filter AND to boil the water before consumption. Water from Guma Valley Company is normally treated at the source with chlorine; it is therefore good for consumption without any more treatment. Disinfection of latrines and shower is the contact action of a solution containing chlorine on the walls, slab and floor of the latrines and showers. It will clean the surface, by destruction of any germ or bacteria. 4. Safety use of the chlorine Chlorine is a powerful chemical that can cause damage to your skin or eyes. When operating with chlorine, always take the following safety precautions: Delimitate a safety perimeter around the operational area. Only two authorized personnel can enter, with proper protection equipment. Place 2 members of the committee to deny the access to passer-by. Do not let children play with the chlorine. While operating the chlorine, wear goggles, mask and plastic gloves. If you do not have such items, wear at least sunglasses and wrap a piece of fabric on your face. Before starting the operation, fill a 5 gallons rubber with clear water and keep it under hand. If chlorine accidentally comes in contact with anybody s eyes or skin, use this fresh water to flush the affected area for minutes. If this does not help, go to see a doctor. If chlorine is swallowed, do not induce vomiting. Give large quantities of water to drink. Never give anything by mouth to an unconscious person. Refer to hospital as soon as possible. Although not a danger for health, be aware that chlorine and chlorine solution can bleach your clothes. Wear old clothes, overall or rain gear.

6 Chlorination of wells and disinfection of latrines ACF / DHMT 6 5. Which method should I use to chlorinate a Well? Check List. There are 3 different methods to choose to chlorinate a well: - The shock chlorination (described page 7) which is used for highly contaminated wells without emptying the well. For the shock chlorination, we will apply a large quantity of chlorine, and therefore the well will have to be emptied by the users the next morning to allow consumption (otherwise the concentration of chlorine would be too high for consumption). - The contact chlorination (described page 13) which is applied after totally emptying the well with a dewatering pump. This will allow the technician to go down the well and brush the walls with chlorine solution. - The light chlorination (described page 14) is a routine chlorination suitable for lightly contaminated wells, or as prevention on a regular basis. This can be done with bleach if HTH is not available. The choice will all depends on the equipment available, the purpose of the chlorination and the type of water well / pump. To decide which chlorination, you will assess the situation in three directions: first to assess the type of water well to chlorinate (location, depth, water table, equipment ), second, the community using the well and third, to take into consideration the context of the chlorination (is it a routine chlorination, an emergency chlorination during a cholera outbreak or a chlorination after works in the well ). 1. Assess the situation with the community members and ask the following questions: Is this water point still in use for drinking purpose on a regular basis? Do you suspect any contamination in the water? Do people have an alternative source of water for the duration of the chlorination process? Is the water turbid? Are people going to organize themselves to pump half of the water in the well the next morning after the chlorination? 2. Consider the quality of the well, the type of pump installed, etc. A well with a hand pump will be easier to empty, making the shock treatment a good option. Do not forget to see if there is a latrine nearby the well. If the latrine is less than 30 meters from the well, there is a high risk of contamination. Even if you apply a shock treatment, the contamination will come back after some time. In such a case, encourage the community to ban the point for consumption or to delocalise the latrines. 3. Take into consideration the purpose of the chlorination: You are sure the well is contaminated, because a water quality test was done and showed a high level of E. coli content, or because users reported accidental contamination (dead animal in the well, object fallen in the well ) or because people are not drinking this water anymore, you will apply a shock chlorination of 100 mg / litre of water. The water will be highly chlorinated, so people will have to pump at least half of the volume of water in the well, to reduce the chlorine content before they can drink the water. If the well is newly constructed, or if some work has been done in the well, especially in the case of covered well with hand pump, you will apply systematically the same treatment before opening the well to public use. If you are not sure that the water is contaminated, if people are still drinking the water, it is better to conduct a light chlorination with a dose of 15 g of HTH for 10 litres of water for each meter of water in the well (see p. 14). This is also the methodology to explain to the communities, since it can be carried out without a lot of equipment and minimal risk. If the water in the well is turbid, it is not possible to chlorinate the well. You will need to empty it completely, and then to apply the contact chlorination described p. 13. This method is to be

7 Chlorination of wells and disinfection of latrines ACF / DHMT 7 used with extreme caution if you do not have the required safety equipment (tripod, ropes, harness ). Turbid water will be a common picture in traditional shallow wells. Be careful, turbidity can increase when you mix the water in the well. In any case, do not forget to ask yourself the following questions: Is this really a water well? This question may seem strange but it is a crucial point: Do not forget that water well is a hole in the ground deep enough to reach the aquifer which is a layer of porous rock (or sand) containing water. The water in the aquifer is normally safe of contamination, because this water is naturally filtered for years and years by the soil and the different layers of rocks and sediments in the ground. Some wells and especially traditional wells in Freetown are not deep enough to reach the aquifer, they are just holes in the ground and the water is coming from a nearby stream, it is therefore a resurgence from the secondary bed of the river, not a water well. The water in such hole is NOT filtered properly by the soil and if the river is contaminated, the well will be also contaminated. To assess whether what you want to chlorinate is a real well with water coming form the aquifer or a simple hole in the ground, check the depth of the well (aquifer in Freetown is generally deeper than 5 to 10 meters). Try also to examine the geological structure of the well. Examine the walls of the well, if it is not lined. If you do not see any difference in the layers of the well there is a great chance that the well did not reach the aquifer. Also check if there is a river or a stream nearby the water point: if that is the case, and if the well is not deep enough, there is also a large probability for the water of the well and the water of the river to be the same. In such a case, the chlorination may be useless if the contamination is coming from the river. What time of the day is it? This question again may seem strange but it is also crucial: to adjust the amount of chlorine to the quantity of water in the well, we will have to measure the water column. In Sierra Leone, most of the users go to fetch water in the morning hours. Therefore, if you take the measurement in the afternoon, there is a strong probability that the well would be almost empty, inducing a wrong measurement and therefore a smaller amount of chlorine that what is needed. When the well will recharge after the chlorination, the water table will come in contact with the parts of the wall that may be contaminated, and there will not be enough chlorine to address this contamination. The only way to avoid this problem is either to organize the chlorination (or at least the measurement) early in the morning before the user s arrival, or to ask the owner of the well to close it until the chlorination team arrive. Is this a well? What time is it? Which method are we Going to use?

8 Chlorination of wells and disinfection of latrines ACF / DHMT 8 TURBIDITY TEST The first step of any chlorination is to assess the turbidity of the water, using a turbidity meter. If turbidity meter is not available, we can fill a plastic bottle with the water and examine it through the daylight. Turbidity characterises a cloudy condition in the water caused by particles in suspension (organic residues, clays, microscopic organisms, etc ). Turbidity is a major constraint for chlorination, as pathogens associated with particles are protected from oxidation. International standards recommend turbidity under 5 units (upper mark of the test) to enable effective chlorination. If turbidity is more than 5 units, or if the water you examine in the plastic bottle is cloudy, you should sensitize the community to alternative option such as household treatment of the water by filtration and boiling or bleach use.

9 Chlorination of wells and disinfection of latrines ACF / DHMT 9 6. Shock Chlorination without emptying the well Shock chlorination is the chlorination of the volume of water contained in the well by introduction of an adequate quantity of chlorine solution in order to reach, in the well, a concentration of 100mg of active chlorine per litre of water. Two important things to remember: We must calculate the right quantity of chlorine to apply. If we put too much chlorine, the water will not be good for consumption, if we do not put enough, the chemical reaction will not function. For this, we MUST estimate the volume of water in your well. We will see how. The chlorine will treat the water by contact: therefore we ll have to mix carefully ALL the water in the well, so that contact is granted everywhere. For this reason, we DO NOT pour the chlorine powder directly in the well. This is useless. We will need to pre-mix the powder in water buckets and pour this solution in the well, and then you ll need to pump to allow circulation of the solution in the well. Always estimate the volume of water in the well and put adequate quantity of powder. Never pour the powder directly in the well. Mix it first in buckets and pour the solution in the well. Items needed Rope and ballast, measuring tape, five 10 l. plastic buckets, one 5 gallons rubber, gloves, goggles, bleach / HTH, brush, plastic spoon, wooden spoon to turn the solution, hose, rubber band, calculator, pen and notebook, broom, cloth, brush. Safety Safety perimeter (only 2 people admitted inside the perimeter), goggles, gloves, mask, 5 gallons rubber with water to wash one s eyes Attention Do not just pour the powder into the well: the chlorine powder is acting by contact with the water. It means that the water, to be decontaminated, must touch the powder. If you pour the powder in the well, only the water located on the surface of the well will be decontaminated. For this reason, you must first prepare a solution of concentrated chlorine prior to the chlorination, and you will pour this solution in the well and pump water up and down. This will allow the chlorine to circulate in the total volume of water in your well. The HTH powder is not always easy to dissolve. We recommend to use plastic bottle and to mix in the bottle the powder and the water. Shaking the bottle will ease the dissolution process. The shock chlorination is done in 2 steps: Step One: To clean the upper part of the well, the pump (if there is one) and the bucket, the rope, the surroundings of the well. This is done with solution A, 200 mg/l Step Two: To disinfect the water in the well, and thereby the walls and bottom of the well. This is done with solution B, to reach 100 mg/l inside the well.

10 Chlorination of wells and disinfection of latrines ACF / DHMT 10 Step One: To clean the upper part of the well. Prepare solution A with a concentration of 200 mg / l of Chlorine in a separate container. If you are using powder chlorine, this will be: If you are using Bleach, this will be: For 10 litres buckets ONE teaspoon (2 g) For 5 gallons rubbers (22,5 litres) 2,5 teaspoons For 10 litres bucket 50 ml (+/- one small tomato cup) For 5 gallons rubbers (22,5 litres) 105 ml (+/-2 small tomato cups) Fig. 2: Preparation of solution A: One teaspoon for one 10 litres bucket. Use this solution for brushing any accessible part of the well, inside and outside. Do not forget the pump and / or the bucket, the rubber, etc. If you can reach it, brush the inside of the walls (be careful not to fall in the well ). If you can do it, open the pump and brush the inside of the pump. Ask a pump caretaker to assist in this operation. Take this opportunity to also brush with the solution the containers people use to fetch the water. Fig. 3: Use the solution to brush the upper part of the well, the bucket, rope, and access cover

11 Chlorination of wells and disinfection of latrines ACF / DHMT 11 Step 2. Chlorination of the water in the well. A. Calculation of the volume of water in the well. For proper chlorination, we need to estimate the quantity of water in the well. This is very important to apply the right quantity of chlorine in the water. If we apply too much chlorine, the water will have bad taste, if we do not apply enough chlorine, the process will not work. To estimate the volume of water is not too difficult. We need an electronic calculator, a nylon rope and a measuring tape like the one the tailors are using. 1. Take the rope and the measuring tape. Do one simple knot with the rope to every meter. This will help to see the height of the water in the well. 2. Attach a weight (a stone, a piece of iron ) at the end of the rope to allow it to sink faster in the water. 3. Wash carefully the rope and the stone with chlorine from the first A solution, to avoid contamination of the water. Do not leave this rope on the floor, do not step on it. 4. Drop the rope in the well. It will sink until the weight will meet the bottom of the well. You will feel it in your hand. Put your eyes on the last knot above the water. 5. Bring back the rope. Count the number of knots. One knot = one meter. Write the figure to not forget it. This is called the water column height. 6. Measure now the diameter of the well, by using the same rope or a measuring tape. 2 persons are needed for this operation, to hold the rope on each side of the well. 7. Write this figure, it is called the diameter of the well. Now, divide this figure by 2 with the calculator. This new figure is called The radius of the well. It is this one you will use for the calculation. 8. Take the radius of the well. Multiply the figure by itself. (i.e. if the radius is 1,5, multiply 1,5 by 1,5; this is 2,25). Write this new figure, it is called square radius 9. Multiply now the figure 3,14 by the new figure of the square radius by the water column height. You will have the volume of water in the well in cubic meters (m3). One m3 is 1000 litres of water. This formula is also noted: Volume = 3,14 x radius² x water column height. Write somewhere the figure of the volume of water in the well, in m3 and litres (litres = m3 x 1000). B. Calculation of the amount of chlorine powder to add in the volume of the water in the well. We are now going to pour chlorine in the well so that the water in the well will reach a concentration of 100 mg of chlorine per litre. To reach this concentration with the HTH powder we need an amount of 140 grams of powder per 1000 litres of water. To reach this concentration with bleach, we need 2,5 litres of bleach per 1000 litres of water. For HTH, Multiply 140 by the litres of the well and divide the result by x Litres in the well = grams of powder to mix 1000 For Bleach, Multiply 2,5 by the litres of the well and divide the result by ,5 x Litres in the well = litres of bleach to mix 1000

12 Chlorination of wells and disinfection of latrines ACF / DHMT 12 Do not pour the product directly in the well. Always pre-mix it with water from the well in clean buckets. It is advisable to share the amount of grams by 100 or by 50 to know how many buckets we will prepare. We will then put 100 or 50 grams of chlorine per bucket or rubber. Round up the last container. One tomato cup of HTH = 50 g of HTH. One teaspoon of HTH = 2 or 3 g of HTH. One tomato cup of bleach = 70 ml of bleach. Example 1. Clean the measuring rope and the plumb head with chlorine solution, dry it with a clean tissue. 2. Take the measurement in the well. In that case, the water table is 1, 5 meters.

13 Chlorination of wells and disinfection of latrines ACF / DHMT Take measurement of the diameter of the well. In that case, the diameter is one metre; therefore the radius is 0,50 metre. The square radius is 0,25 (0,5 x 0,5) We will calculate the amount of water in the well as follow: 3,14 x 0,25 x 1,5 = 1, 1775 m3 = 1 177,5 litres of water. We will now calculate the quantity of THT to apply to reach the concentration of 100 mg/l of active chlorine. Since we use HTH containing 70% of active chlorine, we need to apply 140 g / 1000 litres. 140x1177, 5= 164,8 g of HTH, rounded up to 165g In that case, we decided to use 3 buckets of 10 litres each to pre-mix the powder. The two first buckets are mixed with one tomato cup each (50g) to meet 100g of chlorine. The last bucket is mixed with one tomato cup (50g) plus 5 teaspoons to meet 15 g. (one tea spoon = 3g, 3x5 = 15g).

14 Chlorination of wells and disinfection of latrines ACF / DHMT 14 B. Introduction of the solution in the well. We have seen how to calculate the amount of water in the well and how to prepare the right amount of chlorine to introduce in the water. The next step is to introduce the water in the well and create agitation to insure proper mix of the chlorine in the water. For this, turn the solution in the well and try to create as much agitation as you can. Splash the walls of the well. Once the buckets are turned in the well, pump water up and down as much as you can to mix the water. Close the well for the night. Introduction of the solution in the well. Note If the water point is equipped with a hand pump it is advisable to attach a hose (2 metres) to the outlet of the pump, going back in the well through the access cover. This will allow you to pump several times the water in and out the well to effectively chlorinate the pump and mix the water. Important remark. The methodology above mentioned is based on a concentration of 100 mg of chlorine per litre. This dose is strong; it will chlorinate the well but is too high for human consumption. It means that, the next morning, people will have to pump water to empty at least half of the water contained in the well, in order to reduce the chlorine concentration before consumption. This operation is long and difficult if the well is not equipped with a hand pump. If you are not 100% sure that the users will do that in the next morning, it is preferable, from the beginning, to reach a concentration of 50 mg / litre of water in the well. For this, keep the same method of calculation and just divide the final result by half (in that case, 165 g / 2 = 83 g). The other option is to rather undertake a light chlorination. You will do so in the following cases: There is one water point only for the community and people will need to fetch water early in the morning. The well is not equipped with a hand pump; the extraction system is not very efficient (the bucket is damaged ) or the well is very deep, meaning the pumping of half the water will be difficult. People are not willing to pump for a long time in the morning, because they have other activities to carry In any case, use your common sense and discuss with the community to assess the situation and find the best solution.

15 Chlorination of wells and disinfection of latrines ACF / DHMT By emptying the well contact chlorination Whenever it is possible, it is advisable to empty the well and to clean it inside. However, this method requires professional equipment and strong safety regulation, since it implies to send a man in the well. We will mention this method in this manual, but we do not recommend using this method if not done by a professional company or an NGO with all needed equipment and knowledge. Warning. For this method you will need a system to access the bottom of the well: a tripod with a strong rope. Do not consider this method if you do not have such equipment. Only professional agents trained and equipped can use this method. The methodology is as follow: - Prepare a solution with one teaspoon for 10 litres in a bucket. Use it to clean the whole upper part of the well as in the previous method. - Empty the well totally. If the well is equipped with a hand pump, pump until dry. If you can access one, use a dewatering pump. - Send a man in the well with a tripod. The man should be equipped with a safety harness (3 points harness: belt and 2 legs); a safety hook, a helmet, gloves, mask (for chlorine vapours), goggles, all needed tools. The tripod should be equipped with a winch and a brake, and should be operated by 2 persons. - Brush the lining with chlorine solution (one teaspoon / 10 litres). - Remove any items that may have fallen down in the well. - If needed, remove mud from the filter bed of the well. - If needed, open holes of the intake with a 8 mm iron rod. - Clean again everything with chlorine solution before leaving the well. - Let the well recharge.

16 Chlorination of wells and disinfection of latrines ACF / DHMT Simple Method Light chlorination This method is similar to the shock chlorination, but you do not have to calculate the exact volume of water in the well. This method is suitable for periodic routine chlorination of wells and the community members can do it with HTH or bleach. It is also preferable to use this method if you are not sure that the people will be able to pump out half of the water contained in the well the morning after the shock chlorination, to reduce the chlorine content. The steps for this method are as follow: 1. Dilute 3 g (one teaspoon) of THT or one tomato cup of bleach in 10 litres of water in a plastic bucket. 2. Use this solution to brush upper part of the well, floor, rope, bucket, etc. 3. Take the measurement of the water column as mentioned in the previous method (rope and knots). 4. Dilute 15 g (5 teaspoons) of HTH or 5 tomato cups of bleach in 10 litres for each meter of water in the well. 5. Pour the water as in previous methodology 6. Close the well for the night. In the morning, draw off few buckets until the water has a slight chlorine smell. The community, who can organize money collection to buy bleach or HTH, can repeat this operation on a regular basis.

17 Chlorination of wells and disinfection of latrines ACF / DHMT Disinfections of Latrines and showers The disinfection of latrines and showers can be done with 2 methods: - Using a sprayer - By hand (no sprayer is available) The disinfection of latrines and showers is a very effective and easy to undertake method to reduce sources of contamination by eliminating germs. You ll need to prepare a solution with one teaspoon of HTH per 10 litres in a bucket. Introduce water slowly and stir with a wooden or plastic spoon to insure proper dissolution. Once this is done, wear the usual protection equipment. Clear the area to disinfect from any food, animal, waste It is also better to broom the floor if it is dusty, to clean the walls if you see spider webs, etc. Install a security parameter to deny access to the area. If you use a sprayer, stir the solution in the tank, pump and spray. There is only one rule to apply: always start to spray on the upper part of the wall, and try to complete one level before going down. Finish by the evacuation hole or latrines hole. If you do not have a sprayer, use brush, broom and cloth to clean the whole area, also staring by the upper parts of the wall. Warning. If your latrines are connected to a septic tank, DO NOT pour chlorine solution, bleach or chlorine powder inside the latrines, as the active chlorine would destroy the bacteria in the septic tank, causing bad smell and overfilling of the tank. At household level, such an operation can be done with bleach on a regular basis (every week ). Equipment needed - Plastic bucket (10l) - One gallon of bleach or HTH powder - Brush - Gloves, mask, goggles for protection - Old clothes or overall - Sprayer - Broom

18 Chlorination of wells and disinfection of latrines ACF / DHMT Household Treatment of the water If you are not too sure of the quality of the water you are drinking there is 2 simple ways to treat it to reduce the risk of contamination To filter it, to reduce the number of particles in the water - 2. To boil it or to add bleach to it, to kill the germs. Always use the 2 methods together. One is not enough. Always start by filtration. A. How to filter the water? You ll need: - A clean bucket - A clean piece of cloth, white by colour is better (1mx1m) - A piece of string Wrap the cloth in 4. Attach it on the top of the bucket with the string. Manage to form a funnel of about 5 to 10 cm of depth. Pour slowly the water through the funnel. Clean the fabric after each use, the best way is to have one fabric for each day, and then to alternate cleaning and use. You can also boil the fabric to sterilize it. B. How to kill the germs? The germs are most of the time attached to the dirt particles. Filtration will reduce them, but some can pass through. You ll need to kill them. For this, you have 2 ways - Chlorination - Boiling For chlorination, you need bleach. Just drop HALF teaspoon of pure bleach in the bucket or container. Shake the container to ensure good mixture. Wait 30 minutes before you drink. If the taste of chlorine is too strong, dilute with more filtered water. For boiling, pour the water in a kettle and allow it to boil for 5 minutes. Leave to cool and drink.