Well Disinfection to Prevent Cholera Outbreaks

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I used to work as a WASH coordinator in a community and do regular well disinfection to prevent potential cholera outbreaks and other waterborne diseases.

We train community health workers in doing so through calculations and measures which is never easy. 

Could anyone suggest a reliable, simple and practical technology or method for less educated staff to maintain well disinfection in a region threatened constantly by cholera outbreak?

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24 Answers

  1. We have developed a mechanical method of disinfection which has no maintenance required and lasts for over 20 years. 

    This technology is being used to provide clean drinking water to over 2,000,000 people in developing countries across Asia as of this year.

    If you are interested in finding out more, please email me at andrew@waterandoilsolutions.com.au

  2. The Speedy Breedy microbial detector is able to test toxigenic vibrio cholerae down to 1 cfu in a 100ml sample. The tester is small, portable, easy to use, with minimal preparation steps. Please see the sample preparation and starting a test videos on http://www.speedybreedy.com/videos/sample-preperation/ which demonstrates how simple to use the tester is. Please contact me if you require further information. Best regards, Clive Chelsom-Pill

  3. The Speedy Breedy microbial detector is able to test toxigenic vibrio cholerae down to 1 cfu in a 100ml sample. The tester is small, portable, easy to use, with minimal preparation steps. Please see the sample preparation and starting a test videos on http://www.speedybreedy.com/videos/sample-preperation/ which demonstrates how simple to use the tester is. Please contact me if you require further information. Best regards, Clive Chelsom-Pill

  4. The Water Network research team has consolidated an answer to the above question. 
    Further input from members is welcome and appreciated.   
     

    Cholera is an infection of the small intestine due to the Vibrio cholera bacterium . It causes acute diarrhoea and in some cases vomiting and muscle cramping. Symptoms can vary from none, mild to severe.

    Cholera causes dehydration and electrolyte imbalance which can have severe consequences – researchers estimate that between 21.000 and 143.000 of people die due to cholera every year, while 1.3 to 4 million get infected.

    The incubation period is from a few hours to 5 days so the disease can spread rapidly.

    Areas especially prone to risk are slums without proper infrastructure, camps for refugees and disaster-struck areas without proper sanitation and hygiene.

    Cholera is often caused by consuming water which contains faecal matter or improper hygiene.

    Groundwater and wells can easily get contaminated if open defecation is practised or if pit latrines are too close to the well. Pit latrines and surface and ground water should be as far away as possible. It is recommended that the well is at least 30 m away from the pit latrine.

    Also, you are advised to check if the septic system is malfunctioning , if the area has one, since this might be causing the outbreaks.

    To prevent cholera outbreaks it is important to highlight hand-washing since some people can be asymptomatic but contagious.

    Furthermore, cholera can spread by food since bacteria multiplies faster on food than in water. Safe food chain should be promoted.

    Disinfecting a well on a regular basis to prevent a cholera outbreak before it happens is inefficient.

    We suggest you train the community health workers to teach the locals about the importance of hygiene – handwashing and the secure food chain as well as how do build sanitation facilities and toilets.

    Disinfecting the well as a method of cholera outbreak prevention is not a good method since the amount of water in the well may vary so the dose of the substance used for disinfection varies and would need to be calculated every time.

    Additionally, after taking out a portion of treated water, it is replaced with untreated water and mixed with the treated one.

    Chlorination is the most efficient method for disinfecting a well if cholera has already been detected in a water source.

    It is important to stress chlorine does not kill all the pathogens, but it successfully gets rid of cholera.  

    It is advised to treat a well (or another contaminated water source) with shock-chlorination after cholera has already been detected.

    Chlorination is a method of disinfecting a water well with regular household bleach or chlorine.

    The chlorine is released immediately and residual chlorine is an indicator of whether the water is safe to drink.

    Free residual chlorine of about 0.5 mg/l is advisable.

    Shock chlorination is NOT a recommended method for treating recurring bacteria problems.

    Shock chlorination should be a "one time only" occurrence.

    Levels of chlorine in water will be high after shock chlorination. Therefore, it is not recommended for drinking and an alternative source should be provided. The treatment should last for 12 to 24 hours and in that period, water should not be used.

    How much chlorine should be used depends on the amount of water in the well, which will depend on the volume of water in the well (depth of the water * well surface).

    The amount of chlorine needed increases with the turbidity of water.

    If water is visibly cloudy, the chances of it containing a great number of bacteria is bigger. Cloudiness occurs due to suspended organic and/or inorganic matter.

    Chlorine readily reacts with all organic matter, cloudy, turbid water will consume and more chlorine than clear water.

    To overcome this problem without increasing the chlorine dose, the water should be boiled or filtered, or alternatively given enough time so that the suspended matter settles.

    After chlorination, the water should not be used for 30 minutes.

    Chlorinated water may not be too palatable.

    Chlorination becomes less efficient with lower temperatures!

    Furthermore, recontamination can easily occur – as soon as the water comes in contact with the bacteria, e.g. someone carrying the disease touches the water.

    Some of our alternative suggestions:

    • Boiling water.
    • Storing water in a bigger tank and chlorinating it inside the tank.
    • Chlorination at household level.

    Boiling water may be impractical or unavailable so it may not be the best solution. However, we would like to state that boiling water will get rid of cholera bacteria.

    If possible, storing water in a tank and treating it with chlorine would be a practical way to solve your problem since the volume of water can be precisely determined so the chlorine dose can be exactly calculated.
    Consider using a product with continuously releases chlorine and maintains the chlorine level.

    Train your community health workers to teach the locals to disinfect the water at household level . They should use regular bleach which is inexpensive. This will be much more efficient and economical than treating the wellwater.

    Chlorine is harmful in high doses, but doses used for disinfection (0.5 mg/l) are safe. 


    Related Documents: 

     

  6. Is your well classified as GUDI (Groundwater Under The Influence of Surface Water)?  If so, have you completed a cost comparison on the extremely high effort of cleaning that you are doing and compared that to moving your well where the surface water is not influencing the groundwater?  I have no idea of your situation or where you're located or if you've done this already or not or on a tight budget but the bcalculation without maybe take 2 hours. GUDI water is the worst and when we come across it we generally end up relocating the well and removing the problem altogether. 

    Another problem you will undoubtedly be facing is high DBPs (disinfectant by-products) such as THMs and HAAs in the treated water due to the high amount of chlorine you are adding in front of the treatment process. As long as there is at minimum 0.1 mg/L of residual Cl in the source water...You shouldn't have any troubles in killing the Cholera. 

     

    Kurt

  7. Hi Etienne,

    It is not very easy to know the quantity of water in the well, the Chlorine/Hypochlorite-based treatable contaminants and the amount of disinfectant (Chlorine, Sodium Hypochlorite, etc) required for efficient and safe treatment.

    I therefore suggest 2 ways; (1). Extracting the water and treating it (prior to bacteriological and physicochemical analysis of the raw water to know the contaminants and if Chlorine is the appropriate disinfectant). (2). Installing the appropriate disinfectant dispenser near the wells, so that those who fetch and use the well water will take an appropriate quantity of disinfectant into their water containers before fetching the raw well water so it mixes well to disinfect the unsafe well water before they use it ( this may need simple monitoring and teaching).

    You can fill the disinfectant dispenser or treat the extracted raw water with our SaferEx - Multi-action Water Purifier that disinfects, coagulates and sediments heavy metals and particles, among other things in a single application and unit process, (https://thewaternetwork.com/_/saferex-multi-action-water-purifier-a-solution-to-water-challenges/blog-Jl6/saferex-multi-action-water-purifier-a-solution-to-water-challenges-4sjP18jNM71wltS8grBy-Q)

    Regards.

    Justin

  8. Dear etienne

    Without more information I am not sure what exactly is the problem. I do share the views of many of the responses regarding the suitability of chlorine and its practical application for well disinfection. 

    My only comment would be to suggest taking a wider view of the problem and, if you have not done so already, view chlorination as one of several barriers for producing safe drinking water. For example, can anything be put in place to avoid contamination of the wells in the first place. In addition, waterborne diseases come with sewage contamination to some extent which would exert a considerable demand on the applied chlorine dose. Some form of prior treatment may be necessary to remove / reduce organic matter to make disinfection more effective. Also, does chlorination need to be undertaken in the well itself as others have pointed out the drawbacks of this approach. Extracting water from the well before chlorination would offer more control over the process.

    Kind regards

    Robert

  9. Disinfection of well water is rather tricky as amount of water is unknown, thus quantity of disinfectant cannot be decided properly. Although chlorine is the most suitable disinfectant for controlling cholera we have to depend on the chlorine releasing agents like bleaching powder / calcium hypochlorite / chlorine dioxide / sodium hypochlorite etc.; all these agents releases chlorine immediately and thus there is momentary rise in free chlorine level. This peak level slowly subsides to lowest level (even nil / zero) depending on chlorine demand of water. Since chlorine demand is not known plus water quantity is not known, treatment becomes blind. 

    What one need is controlled release of chlorine to maintain at leat 0.5 ppm free radical chlorine for prolong time, preferably all the time. Such maintenance of chlorine in continuous operation is made possible by using product CHLORITARD developed by us. It is used for maintaining chlorine continuously for period of 1 month in overhead water tank consumed and filled daily (once or twice). It has to be replaced every month by choosing pouches of various capacity ranging from 500 lit water used per day to 50000 lit water used per day. For higher capacity water use, multiples of pouches can be used. This do not require electricity or any technical support, thus illiterate or village people can use it comfortably. Kindly contact me for further details at vm@vmbiotech.com  

  11. Many responses have recommended chlorine to disinfect. While chlorine is the standard choice for treating water with cholera or better vibrio cholerae it would have a high demand as chlorine gets consumed very rapidly.

    It is better to use chlorine dioxide as SCD (Stabilized Chlorine Dioxide) with an Oxy Chlor Generator by dosing the precursor chemicals directly into the water intake pipe. The precursor chemicals are 2.5x more powerful than chlorine. 

    Besides this chlorine dioxide will have a longer residual time in the water to prevent other forms of bacterial, viral contamination.

    Most importantly when you are treating raw water in a well the raw water has presence of organics (Humic & Fulvic Acids). When chlorine comes in contact with these organics there is production of trihalomethanes, that are known carcinogens (Chloroform). This is also the case if you treat the well water with Ozone. Ozone produces bromides, that are known carcinogens.

    Chlorine dioxide when added to raw water do not form trihalomethanes, known carcinogens. 

    So while you may eradicate cholera from the well water you are creating other issues. 

  12. In addition to previous comments, I would advise caution if using household products for chlorinating water supplies - these products are not intended, manufactured or approved for consumption and may themselves cause illness.

    In the UK there are lots of approved products for disinfecting water supplies and for emergency disinfection, something like Instachlor/Steadichlor would probably be a good product to use.  These are produced in a tablet form and normally have dosing instructions on the packaging.  It would be important to at least try and follow basic chlorination principles so as per previous comments, it would be best to chlorinate into tank, ensuring all of the water is chlorinated (ensuring breakpoint chlorination is achieved - particularly if ammonia is present) ensuring minimum contact time is achieved.  It would also be a very good idea to be able to measure the free and total chlorine level in the water (and aim to achieve a difference of less than 0.2mg/l) - there are simple-to-use non electric products (comparators) produced by companies such as Palintest/Lovibond that could be utilised.

    It's also worth noting that chlorine based disinfection will not necessarily remove all harmful pathogens - there are many that even high levels of chlorine will not remove.  Effective disinfection by chlorine (like all other forms of disinfection) requires the water to be free from turbidity/suspended matter (and other challenges) - this may require further treatment such as settlement/filtration prior to disinfection.

    I would finally comment that assessing the point of supply for sources of contamination would be as important as disinfecting it; there should be no potentially contaminating activity (sewage tanks/latrines, livestock etc.) within 50m and the head-works of the asset should be raised above ground level and capped.  There is a lot of information online regarding correct protection of such assets so I will not repeat it here.

  13. Cholera is a diarrhoeal disease caused by infection with the bacteria  Vibrio cholera . It is water- and foodborne disease with person-to-person transmission resulting from poor hygiene, limited access to sanitation, and inadequate water supply, which all contribute to the rapid progression of outbreak. Cholera outbreaks can occur during emergencies, such as earthquakes and flood events, or in refugee settings when water supply, sanitation and hygiene (WASH) infrastructure is compromised.

    The treatment and distribution of water for safe use is one of the greatest achievements of the twentieth century. Before cities began routinely treating drinking water with chlorine  cholera, typhoid fever, dysentery and hepatitis Meeting the goal of clean, safe drinking water requires a multi-barrier approach that includes: protecting source water from contamination, appropriately treating raw water, and ensuring safe distribution of treated water to consumers’ taps.

    During the treatment process, chlorine is added to drinking water as elemental chlorine (chlorine gas), sodium hypochlorite solution or dry calcium hypochlorite. When applied to water, each of these forms “free chlorine,” which destroys pathogenic (disease-causing) organisms.

    Chlorine readily combines with chemicals dissolved in water, microorganisms, small animals, plant material, tastes, odors, and colors. These components "use up" chlorine and comprise the chlorine demand  of the treatment system. It is important to add sufficient chlorine to the water to meet the chlorine demand and provide residual disinfection.

    Halazone Tablets are available in the following strengths:

    4 mg To treat 1 liter water.

    20 mg To treat 5 liter water

    40 mg To treat 10 liters water.

    80 mg To treat 20 liters water.

    100 mg To treat 25 liters water.

    200 mg To treat 50 liters water.

    400 mg To treat 100 liters water.

    Calcium Hypochlorite based Chlorine Tablets

    Chlorination of water is one of the worldwide-accepted method of disinfection and purification of water to make it potable. For inexpensive, economical and timely purification of drinking water, under the various schemes of protected water supply in rural areas, Chlorine Tablets are highly effective. This is the easiest method of disinfection and purification of water.

    In addition to controlling disease-causing organisms, chlorination offers a number of benefits including:

    Reduces many disagreeable tastes and odors;

    1. Eliminates slime bacteria, molds and algae that commonly grow in water supply reservoirs, on the walls of water mains and in storage tanks
    2. Removes chemical compounds that have unpleasant tastes and hinder disinfection; and
    3. Helps remove iron and manganese from raw water.thogenic (disease-causing) organisms.

    it would be ​far more ​effective to ​train health ​workers or well ​attendants to ​chlorinate the ​water one In such cases, it is the monitoring of the sudden drop in the  chlorine  residual that provides the critical indication to  water  system operators that there is a source of contamination in the system.  Water  treatment transforms raw surface and groundwater into safe drinking  water .

    Emergency Disinfection of Drinking Water. ...

    METHODS OF EMERGENCY DISINFECTION.

    Chemical treatment: When boiling is not practical, chemical disinfection should be used. ...

    CHLORINE BLEACH: Common household bleach contains a chlorine compound that will disinfect water. ...

    GRANULAR CALCIUM HYPOCHLORITE. ...

    CHLORINE TABLETS.

     

     

    ​

  14. etienne kayonga 

    i do not understand why you would chlorinate tbe well directly, this is terribly inefficient and almost impossible to get right, as your experience indicates. the mass balance in the well is not static, as chlorinated water is removed it is replaced by unchlorinatef ground water, diluting the chlorine solution and rendering it ineffective as a disinfectant. There is no need to clorinate a protected well, and chlorine solution should be used to wash the well lining, rather than chlorinate the water in the well. 

    it would be far more effective to train health workers or well attendants to chlorinate the water one it is in collection & storage vessels. more effective still would be to train health workers to train households to filter and chlorinate their own water. 

    in terms of controlling cholera trying to maintain a disinfection dose in a well is ineffective and wasteful, you are quite literally throwing your expensive chlorine down a hole in the ground. if you are committed to chlolera prevention a more effective approach would be:

    1. Support chlorination at household level.

    2. Increase storage capacity at house hold level (storage for 18-24 hours would be a significantly more reliable treatment than disinfecting the well water, see WHO water Quality Guidelines)

    3. Place emphasis on the safe food chain (cholera transmission requires a highi infectious dose, and food is a more likely route than water as if food is contaminated the bacteria can multiply more readily on the food than in water)

    4. Emphasis on handwashing (the majority of people infected are asymptomatic but contagious)

    Please stop throwing your chlorine down the well, it is wasteful and ineffective.

    Please note that I have over 20 years of experience in WASH, and was a global technical adviser for Oxfam for several years. I include this to let you know that I am not making the preceding points up. As far as I am aware there is no evidence that chlorinating wells is an effective approach to cholera prevention, but there is significant evidence that the approaches outlined above are.

    Best regards

     

    John Cody

     

     

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  15. Add 50ml un-perfumed household bleach per 100 users per day will give about 3mg/l chlorine dose. If this results in a too-strong chlorine taste, reduce amount but do not dose less than 25ml per 100 users per day. Assumptions - 25 l/person per day, and bleach is at a concentration of 15% available chlorine.  Of course all contributions below are valid, but this is a simple calculation for health workers which should be adequate for most situations. 

  18. Normal house hold liquid bleach (chlorine )is available at super markets use for washing clothes or other use,this can be USE at the village level for disinfection purpose,Use the lid as measuring tool or better still a beaker to use

  19. Normal house hold liquid bleach (chlorine )is available at super markets use for washing clothes or other use,this can be USE at the village level for disinfection purpose,Use the lid as measuring tool or better still a beaker to use

  20. First of all  you can't just dose chlorine or chlorine by products without knowing the physical and chemical  characteristics of the water you're about to disinfect, for instance the dissolved iron content and turbidity of the water. Dissolved iron because iron react with chlorine or chlorine by products and until and unless you what the iron content is or the free available chlorine after reaction you might not be able to attain efficient disinfection. Secondly, the turbidity of the water also plays a role in efficiently disinfecting the water because it shields the microbes from the lethal effect of the chlorine. So, after establishing the turbidity and to a large extent the dissolved iron content of the water, get three or five dark bottles that can contain at least 1000 ml of water.

    Dose a different quantity of the disinfectant into each bottle containing the 1000ml of the water to be disinfected, then allow it contact time and measure the free and the residual chlorine. Remember beside chlorine being an efficient disinfectant it is also a carcinogenic substance and it can also create taste in the water. So, to be fair to the people you're assisting this  series of test called " Break point Chlorination"  could be carried out for a whole year in order to establish the seasonal variation in the water quality and with that the people will not concern themselves with all the calculations you're making reference to in your question.

  21. Joe Cotruvo answered the dose requirement and chlorine sources that can be used.  However, the application depends on the system.  Is this a well that pumps water to a large storage tank?  Is this a manual well that people pump the water from themselves?  The application will determine the appropriate technique.  For a well that feeds a large tank, the simplest method is a venturi injection system.  When the well comes on the dose is consistent as long as there is a chlorine supply (tablet feeder, chlorine bleach tank, on-site generator, etc.).  If individuals are manually treating the water and have their own source of chlorine, then they need the appropriate measuring devices for bleach or chlorine tablets, etc.  Of course I am biased here, but we sell an individual or family sized 4 oz. (108 g)  small hand held electrochlorinator that operates from the on-board solar panel or USB port.  300 liters treated per charge and the device has 1, 2, 5, 10, and 20 liter settings.  The device (H2gO Purifier) automatically produces the appropriate dose (2.5 mg/L) for the volume selected.  No measuring required. Simple to use.  lasts 10 years.  Built to military specs.  www.aquaresearchllc.com. 

  22. the  poor generally store their the drinking water in a simple filter container  made of aluminium.  if they filter it through a double cotton cloth & keep a copper ring permanently in the filter vessel overnight it will kill the bacteria & make it fit for drinking & cooking. 

  23. It does not require very much  chlorine, but it must be continuous. As you well know there are numerous easy to manage methods, that vary by cost and availability in some areas.  The simplest is sodium hypochlorite (laundry bleach)  that can be purchased or  produced on site by electrolysis of salt solution, including solar source electricity. I once saw a bicycle  operated electricity generator.  Since it is a liquid, it is easy to meter in at a continuous rate. Calcium hypochlorite is stable and available, but a solid. Chlorinated isocyanurates that are often used for swimming pool disinfection, are also stable solids that  can also be used for drinking water-see WHO Guidelines. The isocyanurates are probably costly by comparison to NaOCl, but more stable. Keep in mind that the concentration x time (CT) determines the minimum dosage. For chlorine at pH 6 to 9 and at 10C, you can get 3 logs of virus removal with 1 mg/l for 4 minutes contact time. Less chlorine is need at warmer temperatures and longer contact times.

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