Chronic Arsenic Poisoning:


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June 27th 2010

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    Providing Pure Water
Distinction between different Countries.

    It is important to distinguish the problems in most of the world, where high arsenic levels are rare, from the problems in Bangladesh and Bengal.   In most of the world, once arsenic has been discovered in drinking water,  the most important action is to provide pure water to those who have been  drinking from the wells.  This was the action taken, for example, in Taiwan, in Chile, and in Inner Mongolia (as soon as the problem was understood).    In the developed countries (in which we include Chile and Taiwan) provision  of pure water is simple, and not overly expensive.  In the United States of America, only a few water supplies have levels of arsenic above 50 ppb, and even the number with levels above the standard of 10 ppb should be easily manageable.   In our listing of remediation technologies we must distinguish methods appropriate for the U.S.A. (and large cities) and those appropriate for villages in Bangladesh West Bengal and Southeast Asia generally.    We concentrate on the latter and Bangladesh in particular.


    A tubewell such as that shown above is simple to drill and seems to get pure water.  BUT  one quarter of the wells drilled in Bangladesh tap an aquifer containing too much arsenic.    This page outlines the different ways that people are using to address the problem and provide arsenic free pure water to all the people in the world, particularly in SEAsia and Bangladesh.    This is a massive effort.    There is of course no exact number, but as of the year 2000 there were 70 million people drinking water with arsenic above the "old" US EPA standard of 50 parts per billion, and 35 million drinking water with levels above the new US EPA and WHO recommended standard of 10 parts per billion.        WHO has an excellent discussion of the scientific issues involved on their website at   

The number of people supplied by each system  varies and the total number of Bangladeshis is therefore not certain.  It is probably less than 10% of the number of  Bangladeshis who need pure water.   This depends upon the nature of the supply systems.  It would be useful if there was a continuous monitoring of the number of systems needed.    This webmaster believes that in all cases it is necessary to monitor the solution.  Is it indeed providing arsenic free water,  bacteria free water a year later?  Measurement is therefore an essential part of any remediation method.     

In Bangladesh there was intensive discussion in 2003 followed by the release in 2004 of a National water policy  with various  annexes and supporting files.  Professor Dipankar Chakraborti of Kolkata outlined in 2005 his strategies for mitigation of the arsenic problems in West Bengal and Bangladesh.   See also a thoughtful description of the alternatives is by Professor Feroze Ahmed of Bangladesh University of Engineering Technology (BUET), in a paper presented at that conference in Dhaka,   and  Professor Ahmed's  edited volume of various recommendations on the problem that is available from ITN, BUET in Bangaldesh.   Anotherimportant report in 2003 was by "NGO's Arsenic Information and Support Unit"  (NAISU).  As we discuss the methods below,  we note that all  will work but need various degrees of care in their implementation.    In all cases it is important to discuss these in the context of the geology of the country, and region concerned.  See the report for the Government of Bangladesh
Quaternary Geology and Aquifer Systems in the Ganges-Brahmaputra-Meghna Delta Complex, Bangladesh  
   In the view of this webmaster,  the most important feature is that the villagers must be fully involved with the decision (a so-called buy in) and be responsible for continued maintenance and monitoring.   There must, of course, be organizations with expertize to advice and help when requested.   A decision between these alternatives should include a discussion of the available follow-up

    Eventually each technology should be subjected to a risk assessment - comparing risks and benefits of the various options.   Even in developed countries such risk assessments are rare and can be misunderstood.   Since the major risk is not of death, a measure must be found of sickness.  Two measures are in use for this "Quality Adjusted Life Years " lost (QALYs) and "Disability Adjusted Life Years" lost (DALYs).  See for example page 12 of "Risk Benefit Analysis"  A  paper using such a procedure has been presented to APSU,  "Risk Assessment of Arsenic Mitigation Options (RAAMO)".    The report finds that the risks of improper use of surface waters outweighs the risk of badly installed deep tube wells.    A more complete report was presented to the Arsenic Policy Support Unit (APSU), now defunct,  in 2006 by MF Ahmed, G.Howard, D. Deere S.G Mahmud, and SKJ Shamsuddin.     It must be noted that the bacteria concentration numbers in the APSU reports for  dugwells is very pessimistic, because a collection of wells was used, some built according to WHO standards and some not, and it appears that none used chlorination.    Moreover the coefficients relating the bacteria concentrations to risk came under very heavy criticism by Professor Allan Smith  in the March 2009 conference in Bangkok and maybe  overestimates.  
Well switching

Left. a well painted green(water safe) and, right, one marked red(arsenic content  is toxic).

    This is in many ways the simplest, cheapest and most effective method of remediation.  It is important to understand the causes of the availability of arsenic in the tube wells and the extent to which the problems can be avoided by careful choice of wells.   John McArthur of University College, London, emphasizes that 75% of the shallow wells are doing what was intended - providing pure water.    The general view is that 33% of the people in Bangladesh villages have switched wells in response to the general advertisement of the problem.  The team of Columbia Uiversity and University of Dhaka scientists find that in Ariahazar Upazilla, where they have been working, 68% of people have switched wells.  This well switching is the cause of the biggest number of persons now drinking arsenic free water who were not before.  Yet in a Government of Bangaldesh survey, this still leaves 1400 villages without any well that is free of arsenic.  Obviously, these villages are priority villages for the pilot projects for the various technologies discussed below.   This issue was discussed by the Arsenic Policy Support Unit (APSU) now defunct in a report "not just red or green".

Various remediation Systems
Small (Household) Scale Arsenic Removal

Use of deeper wells
Surface waters
        Sanitary dugwells
        River Sand Filters
        Pond Sand Filters
Rainwater collection and Storage
Large Scale arsenic filtration

Small (Household) Scale Arsenic Removal

    At the first  International Conference  on Arsenic in drinking water, held in Dhaka in February 1998 simple methods for each household to filter the water were suggested as an immediate short term solution.  They have in common a series of containers.  Water is poured into  the top container and filters  through sand and iron chips to the bottom container where the water is now free  of arsenic.  It was hoped that these methods would be easily used by villagers,  would use local materials,  and be affordable.    Several groups  claim lasting success.  
Here is a 2001 report of several systems by an independent company, WR Akins.

Guy Howard of the Bangladesh Arsenic Policy Support Unit pointed out that there were, in August 2005,  100,000 household arsenic removal units in Bangladesh.   Dr Abul Hussam of George Mason University, with his brothers in Kushtia and Dhaka,  designed and market the  SONO/MSUK filter. 21,000 SONO filters have been distributed throughout Bangladesh by May 2006.   They are marketed from their base in Kushtia.  400,000 people drink water from these filters from may parts of Bangladesh as shown in themap..   PDF files of photographs and other details of the SONO filter can be downloaded.   Professor Abul Barkat of the University of Dhaka comments that they "have collected  data for last four years (that's how long some of these filters are running).   More than a billion liters of water has been consumed from these filters. The  filter has been optimized to last for seven years minimum at a cost of $35.00"     The system is continuously being modified and updated.   The importance of the back up that is provided for the SONO filter is the example of a dozen filters that were supplied in the village of Eurian in eastern Bangladesh where Dr Chakriborti of Kolkata and DCH are working.   The tests, in 2005,  of these filters in the field by DCH were far from satisfactory.   Dr Hussam believes this was due to a manufacturing defect that has now been corrected and the group has replaced the filters at no charge.   The test results of the replacement  filters are excellent.  This emphasizes the importance for this method, of  expert back up. The need for expert back up  probably applies  for all mitigation methods!   A recent independent report on the SONO filter shows that this filter is playing a major role in reducing the Bangaldesh arsenic problem. Additional data on the tests on the SONO filter installed by BAMWSP-DPHE in Hagijang, Chandpurhas can be found here. Furthermore, the water quality test report on the SONO filter installed by the BAMWSP-DPHE in Gojaria, Munishijang  can be found here.   The SONO filter by itself does not grow bacteria as shown in tests  by Village Education Resource Center (VERC),

In other locations problems arose.   According to the 6th report by the Jadavpur University team, 80% of Arsenic Removal Systems (ARS) in West Bengal are not functional.  Not only is it a waste of several millions of dollars but also it is a tragedy of false hopes.      It was noted as early as 1998 that the systems then proposed all had a problem of "breakthrough"    After a certain time, the filtering action ceases, and even some of the arsenic previously trapped comes back.   The existence of the "breakthrough" was a primary reason that the filters were proposed, as stated on this site at the time, solely as a short term solution.    A possible reason for the failures is explained in this note from Professor McArthur.  "Do they know the water is Fe-rich? If not, find a way to tell them. It might change their view of the matter, because, unless Fe is removed before the As plant, it messes up a good deal of the removal technology currently available: and, as an Fe-removal plant aerates and precipitates FeOOH, it removes most of the As. This is standard (old) technology. If they fund someone who does not know the water is Fe-rich (and most don't) they may put a big sum into methods doomed to fail. Attached is a good example: a year old and doomed to follow 20 or so other clones now abandoned that litter my field area in West Bengal. Raw feed is 900, output 300 and climbing, blocked by Fe most of the time: a disaster."    Another reason may be that villagers found them too complex to use.

    In this connection it is very encouraging that the SONO filter has so far experienced no breakthrough.    Whether the break though will come in 7 years, 20 years or not within a lifetime is unknown.   But this gives a user, and those recommending their use, enormous confidence.   It seems clear that the reliability and effectiveness of Arsenic Removal Systems depends upon the water chemistry, and probably on the maintenance.   It is also unclear whether laboratory experience is predictive of performance in the field.  It is unclear to this webmaster whether the SONO or other filters work on all waters in Bangladesh;  and if a particular ARS only works on some waters how to decide whether it will work on a particular village water and how to explain all of this to the villagers affected.

  In 1978 the Government Of Bangladesh   instituted a program now called BETV-SAM (Bangaldesh Environment Technology Verification-Support to Arsenic Mitigation) to verify the claims regarding the efficacy of Arsenic Removal Technologies and  appointed BCSIR ( Bangladesh Council of Scientific and Industrial Research) to carry out this program. BCSIR is being assisted by OCETA (Ontario Center for Environmental Technology Advancement) of Canada. This program was supported by CIDA and BAMWSP (Bangladesh Arsenic Mitigation Water Supply Project financed by the World Bank).      Under the current GOB regulations, no arsenic removal technology may be deployed in Bangladesh unless it is cleared by the BETV-SAM program.    In February 2004 the first four technologies were approved for "provisional" use and are now being sold -READ-F, SONO 45-25 (the system noted above designed by Dr Hussam for which he has been awarded the Grainger challenge prize ), Sidko and MAGC/ALCAN.   For three years the webmasters unsuccessfully tried to obtain a copy of the report but now  the report of  BETV-SAM has now been posted on the BAMWSP website and is copied here.  

     It is noteworthy that  releases of the test results failed to note the important fact that only the SONO filter had no 'breakthrough". 
In Nepal, the KANSHAN filter has been deployed by Susan Murcott but the webmasters have no test data thereon.

    A new system, Electrochemical Arsenic Removal (ECAR) has been developed at Lawrence Berkeley Laborotary is is now being tried in the field both in India and in Bangladesh.    This webmaster has no opinion yet on the relative advantages and disadvantages. 

    Medium (community) Scale Arsenic Removal

    The pessimistic conclusions of Chakriborti and McArthur are also challenged in West Bengal by Arup Sengupta of Lehigh University ,  John E, Lee M. Blaney, Owen E. Boyd, Arun K. Deb, and the nonprofit organization Water For Peopleand colleagues in Bengal Engineering College.   Their detailed paper of the results of follow up on over 150 (now 200) medium sized systems seems convincing.    As of June 2011 their Tagiore-SenGupta Foundation was awarded the first prioze of $50,000 in the Reed-Elzevier environmental challenge for this fine West Bengal.    The cost is about $1,200 for a unit which purifies water for 300 families or about 1200 people.  This works out at $1 per person.   We are delighted that the Silver award of the Grainger Challenge Prize of $200,000 has been awarded to this details of  the award can be accessed here.    Anyone interested should call Dr Anriban Gupta at Bengal College.   As of June 2011 their Tagiore-SenGupta Foundation was awarded the first prioze of $50,000 in the Reed-Elzevier environmental challenge for this fine West Bengal.  

    In 2006 this webmaster made a  tentative conclusion:  it is vital to have a village community that is committed to follow up maintenance and hopefully a nearby institution  for expert backup information and advice.   In 2011 he is more sure of this than ever.

Subterranean Arsenic Removal

    In some places it may be possible to remove the arsenic by oxidiation of the aquifer.   This is the aim of the Subterranean Arsenic Removal (SAR) technology proposed by Mukherjee of Kolkata, India.   They cliam" This technology can transform the way arsenic is removed from groundwater in Ganges, Brahmaputra and Mekong delta where the arsenic is of arsenopyrite origin, saving millions of lives. This includes affected areas of India, Bangladesh, Cambodia, Nepal, Vietnam and Thailand. The technology is about to be implemented in Cambodia and Burkina Faso with the help of Royal University of Phnom Penh and ‘Friends in Action International’ respectively, subject to proper research. The technology is scalable from a production capacity of 10,000 litres/day (USD 4,000) to 1,00,000 litres/day (USD 20,000) for each plant, catering to the drinking water needs of 2000 to 20000 people, depending on the soil & water conditions."   A couple of years ago Harvey tried expeiments along these lines with limited success

    Use of Deep Wells

   The information from  well water surveys such as that of the British Geological Survey and Mott MacDonald   shows that many deep wells, greater than 150 meters in depth, are free of arsenic.   This seems to be confirmed by more detailed studies from an MIT/BUET (and others) group and a Columbia University group.   Dhaka and the southern part of Bangladesh (where salt water enters the shallow aquifer)  are mostly free of arsenic.  The reason appears to be that there is a clay layer below the aquifer from which most tubewells take their water and these deep wells tap a lower aquifer.   But this is not true, for example, in Jessore where there is no clay layer.   It is claimed that these deep  wells are cheaper  than most other alternatives. As of 2009 this has been the major mitigation solution and is supported by the funding agencies, World Bank and UNICEF and the Department of Public Health Engineering (DPHE).  More important, however, is that these retain much of the simplicity of the "ordinary" tubewells and require less care in construction and less maintenance than other solutions.   Details are available  in  the  report of the Ground Water Task Force, July, 2002 and a detailed report of the Deep aquifer Data base and Preliminary Deep Aquifer Map.  (Local Governme/nt Division,  GoB March 2006)  Full Final report ContentsChapters1&2  ,  Chapter3Chapter4  ,  Chapter5.1-5.4, Chapter5.4-5.44Chapter5.5 , Chapter 6Chapter7Con  , Chapter8Ref ,Chapter9Appendices. A comparison of the Bangladesh government reports in 2002 and 2006 shows the increased confidence in deep tube wells as the preferred  solution for 75% of the country.

     But there are potential  problems that should be considered in any implementation:
    - if such wells are dug carelessly, and not properly grouted, there is a possibility of "shunting" the aquifers and allowing water from the higher aquifer to contaminate the lower aquifer. 
    - it is unsure whether the lower aquifer is a "closed" aquifer from a hydro geologic point of view or whether it is as easily recharged as the upper aquifer.  
    - It is unclear whether, in a longer term, pumping from these wells would increase the arsenic level.

    These can be checked by frequent (once a year) measure of the arsenic levels.  If arsenic levels are rising,  other solutions must immediately be found.   Since money would be saved by using this cheaper method,  the money could be set aside for such eventualities in what, we all hope, would be a limited number of locations.    Such a commitment should be made in advance.     In 2002  many experts were dubious.     Dr Dipankar Chakraborti was still cautious in 2005.   The report by the Arsenic Policy Support Unit (APSU) "Risk Assessment of Arsenic Mitigation Options (RAAMO)" finds little arsenic and almost no bacteria in a selected group of deep tube wells.   Nominally they were selected randomly but that means little since it is strongly believed that the quality of deep wells is very dependent on geography.   Nonetheless this is highly encouraging and suggests that some of the caution in the use of deep tube wells may not be justified.   Indeed this reviewer would emphasize that at the worst, a deep tubewell would produce arsenic-free water for 10-20 years, and might do so for well over 100 years.   Since the cost may be lower than other alternates,  it would in most cases be well worth a try.

There are many indications that Manganese can be found in deep wells.    This can be a problem in itself.    A recent paper discusses the effect on school children
    Return to Surface waters.


    The reason for installing tubewells between 1980 and 1998 was to avoid the problems of sanitation and in particular to reduce cholera.   If Banglaesh is to retrun to use of surface waters Although n 2003 it was the official Bangladesh National Water Policy to return to the use of surface waters whenever possible.   Yet the Report of  the Committee on Surface Water Development and Management for Drinking Water Supply in the Arsenic affected areas of Bangladesh, July 2003  pays inadequate attention  to assuring sanitation and in most cases, chlorination.     As a result many surface water solutions were construction with inafdequate attention.     One Non Governmental Organization (NGO),  Dhaka Community Hospital, (DCH) has paid attention to sanitation from the outset and also, through its medical clinics, has considerabel community involvement.   This webmaster pays, and will pay especial attention to their work.. 

    There are three imporant steps. 
    A proper protocol for construction
    A proper protocol for maintenance
    A proper protocol for chlorination if necessary

    The first two protocols will vary with the surface wter chosen.   But the clorination procedureapplies to them all.     In the western world, water from whatever source is first filtered to remove as much organic matter as possible and then chlorinated.    These are for example discusded in a historical paper by Okun.  

    It is now clear from measurements that chlorination can keep wells free of bacteria and should be done at least every 2 weeks.   This is shown in particular by measurements by DCH of bacteria  the wells in the PABNA region   Although measurements continue, this problem which has set back the use of surface  wells is probably now solved.

    Another possibility is to accept the surface waters and filter them on a small household scale and then chlorinate the water.   This is done in the Mukti Pani filter, proposed by Meer Hussein of Kansas.   The webmasters have no measurements on the effectiveness of this and welcome any measurements that we can post on this site.    Other filters exist for large scale bacteria removal such as the Pure Safe Water using filtration and ozone.

     In the past (50 years ago) many of the villagers drank from "holy" ponds where the water was protected from animals and cattle. Many of these were unsanitary. It was to prevent water borne diarrheal diseases that the tube wells were suggested.
   A return to surface waters must therefore be done with full regard to better sanitation than before.  In particular this webmaster recommends rigid adherence to WHO standards.    Waters should be tested for coliform bacteria, not just once but regularly and in particular at the worst period - the end of the dry season.    Disinfectants such as lime can work for awhile after complete cleaning, but regular chlorination is far superior.   Use every 2 weeks is recommended.     Indeed in the USA Some wells are chlorinated daily.  Tests should be made before the disinfection, not only just afterwards,  to be representatative of the worst time.     Also in the rainy season when the ground is water logged and the ability to filter bacteria is lost.    Public confidence was lost when water from the tube wells were found to contain arsenic.  It was lost again when the Arsenic Removal Systems were not successful in many places.    Confidence once lost is hard to regain.   For that reason, among others, this webmaster recommends that in order to inspire public confidence these measurements must be available for public inspection  (for example the measurements of the dugwells installed by DCH are in a directory on this website.) 

Use of Dug Wells

  DCH Dugwells  list  details
    Before the (cheap and simple) tube well was introduced,  many villages dug wells to obtain surface water.  However,   many, if not most,   were NOT carefully installed, dug, covered, and chemically treated, and they were full of bacteria.    Successful projects involving sanitary dugwells exist in other countries, and some that may be successful have been reported but not yet in the detail to convince the skeptics that no coliform bacteria exist.  Here the webmaster reports primaily on the work of Dhaka Community Hospital (DCH) .    The site selection is the first step in a construction protocol.  Wells must be remote from latrines, old or new. 
Adetailed paper includes the detailed construction protocol.     WHO has suggested similar guidelines so has Chakriborti Grameen Bank now has a similar list. They must be covered to prevent entry of animals and refuse but is aerated to allow oxidization.  Water is taken out by a connected tube well and pump, making them as easy to use as a tube well. They are located at a distance from latrines including past latrines with their buried organic waste if possible.

    In many wells, the water is pumped by electricity to an overhead tank fro which PVC pipe leads to half a dosen taps in indididual houses or between houses.   This system of running water is popular,  but cost of electricity prevents it being run continuously.. 

    The well maintenance is crucial.     DCH has a protocol for this and will not help a village with a new well unless they agree to follow the protocol with a custodian to implement it.    But in the protocol for measurement  DCH initially made an error.   Initial measurements of 66 wells in the Pabna upazilla showed no coliform bacteria and it was incorrectly concluded that chlorination was unecessary.     But later measurements of some of the PABNA wells showed high levels of faecal coliform bacteria.   Although the cause of the error is uncertain, it seems likely that measurements were made soon after cleaning and maintenance instead of just before.   All the DCH measurements are available in a directory, DCHTests,  on this site.    DCHTests.   Chlorination tests were was begun in Pabna in 2006.    Household bleach (5.5% chlorine) was used.   The amount was determiend by a US EPA recommendation for "shock" chlorination and successfully brought the levels of coliform to zero.       It seems that three weeks after maintenance coliform levels rise again, and the recommendtion to each well custodian is to chlorinate weekly or at least biweekly.  \

The simple, portable tests for bacteria are simple yes/no devices.   If chlorination gets the level to zer, as it is in the USA,  then they work.   But in Bangakledsh this has proved difficult at a low, but non-zero level is accepted.   For this, there exists no cheap field test.

Reports on DCH work: 
List of DCH Dugwells (224) as of May 2009
2nd phase
(in html) and  (msword)
       pipingto individual houses
       layout of the piping)
third phase in (msword)
pictures from the webmaster's visit
DCH Tests
Initial tests 2001-2004 (EXCEL file)
Measurements on 48 wells in Siridjikan
Dr Chakraborti reports on tests of 483 dugwells in West Bengal confirming that most are arsenic free.   No measurements of coliform bacteria are available to this webmaster, but Dr Chakriborti recommended disinfection with chlorine once a month.

Project Well  in West Bengal, directed by Dr Meera Smith,  has published details on about 170 sanitary dugwells in West Bengal;   A detailed listing showed high initial levels of arsenic in two wells.  These high levels went down with time.  According to the most recent report suggests that they are chlorinated every 2 weeks,   and no high bcteria lvels re reported.   But it seems that the bacteria levels are not brought to zero

Meer Husain of Kansas has also joinned in recommendations for surface watrers  with filtration and chlorination.

The status of the chlorination and coliform measurements is unclear to this  webmaster.

    CRITICISM of dugwells

The  Arsenic Policy Support Unit (APSU), a Bangladesh Government group, reported in June 2004 that 1,524 dugwells  had been dug by 6 groups:  BAMWSP, DPHE-Unicef, DPHE-Danida, World Vision, WATSAN, and Asia Arsenic Network.  By 2009 it was orally reported that 4000 new dugwells had been built.   Of these many, perhaps half, have been abandoned.   Of the  240 DCH wells only 7 have been abandoned for various reasons.    This webmaster has been unable to find details of these other wells.

    The dugwells, with pipeline,  are a further step in matching the history of the water supply in the small English village in which Richard Wilson lived from 1953-1955.  For several centuries, a village well existed from which everyone drew water in a bucket.  In the 1930s, the well was covered and a windmill installed to pump water to a storage tank with water supply to one tap in each cottage.  The cottages were "modernized" by installing staircases to the upper floors to replace the ladder.  In the 1940s a small petrol (gasoline) engine supplemented the windmill when the wind died down, and a bathroom was installed in the cottage in which Richard Wilson lived.  In the 1960s, the main water supply pipe to the city of Oxford was brought within 1/2 mile and the village connected to main water.   

    In 1998 it was a puzzle to many geologists,  and even some hydrogeologists,  why the surface wells were free of arsenic. For they seemed to be sample the same water as the shallower tube wells, and in many locations shallow tube wells showed concentrations of arsenic concentrations increaing with time.   Why does this not happen in dugwells?   This question, asked 6 years ago has never been satisfactorily answered.   There are several possible answers.  Firstly, over centuries people used dugwells, mostly unsanitary, but no arsenic problems were ever reported.  Secondly the experience of DCH, Meera Smith and Dipenkar Chakraborti suggest a difference.   
They claim that the shallow dug wells were likely to be less polluted than shallow tube wells because, being wider (often over a meter diameter) they allowed access of oxygen and so would oxidize dissolved ferrous iron and that would scavenge arsenic from the water.  Also the top of the aquifer is the freshest, youngest water,   which has been most recently recharged by flood (rain) water,    and so the least likely to be polluted by iron reduction.   On coming to the surface in a dug well the water oxidizes and deposits arsenic,  by co-precipitation with FeOOH or sorption onto existing FeOOH in the sediment.    This argument may not apply to a small dugwell where water is continually coming in from the side and aeration may not be complete.     

    The dug wells generally sample water that is shallower than the shallow tube wells. Dug wells are dug until the water table is hit, plus a bit more. Those dug in December, when the water table is high,  sometimes went dry in a dry year.  They were often a bit shallower than those dug in May at the end of dry season.  Shallow tube wells are sunk until the first good clean aquifer sand in found, then are made 20 foot deeper to accommodate the screen,   Much of the pipe comes in 20 feet lengths, so that "shallow" tube wells may be 20 to 30 meters deep (5-7 pipe lengths, including screen).

River Sand Filters

    DCH River Sand Filters.
River water is often pure, but in tropical countries it is usually not.   Nonetheless it may be collected and filtered.    For example in 2002-2004 Dhaka Community Hospital using funds provided by UNICEF constructed 6 River Sand Filters in the Saridjekan upazilla.    Water is pumped into a series of 6 tanks containing sand, from which it is pumped up to an overhead storage tank before being fed to a number of taps for the villagers.   Although the supply for each of these systems is adequate (6 liters per person per day) for 250 families, only 107 use the water from the River sand filter (RSF1).    The custodian of the system spontaneousyy told this webmaster on his 11th January 2009 visit that he and the  villagers are very happy with the system.   Tests of water quality in 2007 through 2013 show consistently good quality in PSF1 to RSF4, but in RSF5 the coliform bacteria rose in the monsoon and the top layer of sand has to be replaced.   But in 2008 to 2013 this is under  control. Normally such cleaning is done every six months.   Details of the construction, and Measurements are available on this site.

Pond Sand Filters


    It seems logical to collect river water in a pond, and then filter it naturally.  Again this has been done for centuries.  Then it can be filtered as it goes into a second pond by sand or soil.  A pond sand filter can purify water for several hundred people so that the overall cost (per person)  is about the same as a deep tube well, but it probably needs more careful maintenance.    The webmaster photographed one system in 2004.   At first it was not bacteria free but it was improved and is bacteria free now.   The Phase 2 report of May 2005 by the Arsenic Policy Support Unit (APSU) "Risk Assessment of Arsenic Mitigation Options (RAAMO) tests 42 Pond Sand Filter systems and found that 95% had bacteria both in the monsoon and in the dry seasons.  They attribute this to inadequate maintenance and poor filter depth.  Again no indication was given that disinfectant (lime or chlorine) was used.    The webmasters have no record of tests with chlorination for pond sand filters, but suggest that chlorination be at least as often as the tests in dugwells.

The abstract of a comparative field study on the effectiveness of arsenic removal from groundwater by household sand filters is available on the ACS website.  

    In India,  
the Jal-TARA Slow Sand Filter is a common water purification systems comprise of chlorination, coagulation and sand filtration techniques. Of all these techniques, sand filtration offers a chemical- free, reliable and economical treatment. Jal-TARA Slow Sand Filter is designed to treat drinking water using slow sand filtration technique as per the specifications of World Health Organisation (WHO). Jal-TARA filter is a biological filter merged with advanced technique of fabric protection to improve and simplify the traditional process of slow sand filtration. Two type of filtration act together to improve the quality of water: It consists of a gravel filter to remove turbidity, and sand bed filters to completely remove pathogenic bacteria from raw water.   

    Meer Husain of Kansas has developed the Mukti Pani filter for filtering surface water and removing pathogens.   He recommends chlorination of the water after filtration.   This seems similar to the 
Jal-TARA Slow Sand Filter noted above.   The webmasters have no information about any measurements of either filter.  We would welcome any measurements to post on the site.

Rainwater Harvesting


Household tanks with a capacity of 3200 litres. Photo courtesy of UNICEF-Bangladesh.

     Rainwater harvesting is extensively practiced in India (W Bengal). Attached is a comment by Dr Meera Smith.

    For anyone unfamiliar with the cycle of monsoon rain and long dry season, it is puzzling why there is a problem  in Bangladesh at all.  One of the web masters lived in an English village where rain water harvesting and storage was usual. But storage was only needed for several weeks.   In Bangladesh water must be stored for several (none!) months.   The size of the tank must be increased tenfold,  and it becomes difficult, although vitally important, to keep the water pure during storage.  Nonetheless it is a solution for many communities where other alternates are not available.  Particularly in southern Bangladesh, where there is frequent flooding, it is almost impossible to make a sanitary surface well, because it is not possible to keep the latrines at a distance from the wells.   Rainwater harvesting is being advocated by UNICEF as reported by Dr Colin Davis at the 5th International Arsenic Conference in San Diego in July 2002.
   As of February 2004,   1000 new rainwater harvesting units were being installed by UNICEF and DCH

    Simple storage of rainwater is not as simple a solution as it may appear from the above description. In some high-iron waters little or no arsenic is found.  Everyone who has looked for microbiological contamination of such stored waters has found gross contamination - water containers act as incubators in the house, especially when they are uncovered or do not have taps. After 12 hours, fecal coliform can be more than 10,000/100ml, or even 'TNTC' (too numerous to count).       
The Phase 2 report of May 2005 by the Arsenic Policy Support Unit (APSU) "Risk Assessment of Arsenic Mitigation Options (RAAMO) tests 42 rainwater harvesting systems.  While less than half were contaminated by coliform bacteria in the monsoon period, this increased markedly during the dry season.         A test of a rainwater collection system on the roof of Dhaka Community Hospital showed that chlorination reduced fecal coliform to less than 10 fc/100ml but they rose drastically again after 3-4 weeks.   Chlorination of all rainwater tanks every 3 weeks seems desirable.                             

Large Scale Arsenic Removal Systems

    There are several  arsenic removal methods, which are appropriate for a large scale (small town) or a medium (village) scale. They are particularly appropriate for countries which have developed a central water supply and can therefore use the economy of scale.   Those must be tested in the field , and attempts must be made to manufacture equipment locally to make them affordable. The web masters have not done so and merely list them below.  A list of larger scale technologies.

    In Bangladesh, UNICEF have helped the Department of Public Health Engineering (DPHE), Government of Bangladesh, to install over 40 community-based arsenic removal plants in different parts of Bangladesh, and  they are running well with the active participation of the community.   Each plant can produce approximately 3,600 liters of filtered water every 15 hours. The arsenic contained in the treated water is below 0.01 mg/L,  which is below the WHO and the new EPA guidelines.   The communities each employ one caretaker for each plant. They are paying salary to the caretaker, the electric bill, incidental expenses, and generating funds to purchase the chemicals in the future.    This experience is very promising for communities of 10,000 people or more where people are willing to walk to the central purification system to collect their water.  Again the webmasters have no up to date report of the success of these purification methods.

The long term future including long term waste

    In 1998 there was a confusing controversy by some over enthusiastic people  (e.g. see the article by Bridge and Husain
) that  the problem is a barrage on the Ganges river.   However this seems to be reliably repudiated (by Dr McArthur from UCL among others).    TIn the longer term (50 year time scale) a national water policy was promulgated  in 2004 to replace the previous one which produced the arsenic problem.   It emphasized use of surface waters.   Yet many more people are uaing  deep tube wells than surface waters.    Many hydrologists see no problem with this but it must be monitored.  The long term, will presumably use water piped from a central system of some sort, and the village size piped systems being pioneered by DCH seem to be a step in this direction.T.

    Whenever arsenic is brought from the subsurface to the surface there becomes an issue of disposal of the toxic waste in the long term.   If merely allowed to salty on the surface, it could contaminate all agricultural products and be a disaster.   This problem arises, of course, with any procedure for arsenic filtration.   It is probably far worse if tube well waters at the 40 m aquifer are used for irrigation, because so much water is so used.  Then water can enter the crops.   A rough guess, based on US data where arsenic used to be spread on crops as an insecticide and forgotten, and some preliminary measurements in Bangladesh,  suggests that this is, at present, equivalent to less than 10% of the allowable (50 ppb in water) arsenic intake.   But it must be monitored.

Improving the Diet

    An important issue for coping with arsenic exposure  is the effect of diet.  A general issue can be stated:  there  is frequently more than one cause of a cancer or a lesion.  For example lung cancer can be caused by cigarette smoking or asbestos or both together,  in  a synergistic  way such that the risks multiply (rather than add) when  both  are present.   In the USA it has been found that people who  have  a good diet of fresh fruit and vegetables  (5 servings per day) have half  the risk of many cancers, including  lung cancers   caused by cigarettes,  as  those without a good diet.  By  analogy,  one might expect that the  lung  cancer risk from arsenic will be less among those with a good diet,  but this is not yet supported by direct data.  Indeed, there are  anecdotal  indications from Bangladesh that a good diet reduces  skin lesions also.  Clearly,  it is a good approach  for many reasons,  but epidemiological studies  to confirm this are highly desirable.

    There are several specific chemicals that have been suggested that would either (i) help to prevent arsenic lesions by rapid removal of arsenic from the body or (ii) help to cure arsenic lesions.  Encouragement of methylation of the arsenic probably accelerates methylation, but the methylation has been suggested as a cause of internal cancers.  
The specific chemical that has come to the mind of many health experts is selenium.   It was noted in the 1930s that effects of excess selenium can be counteracted by adding arsenic to the diet because As and Se combine.   Does the inverse take place?  It  is  reported that areas with high incidence of arsenical lesions have  low selenium  in the water.  Some victims have low selenium levels.   Does adding selenium to the diet really help, either to prevent the lesions from forming (likely), or to treat them afterwards (less likely)? We have,  with help from others, compiled a list ofreferencesand arecent paper  on the subject.    Professor Zuberiof Rajshashi University has suggested methionine to reduce the arsenic lesions.  Dr OGB Nambiar has suggested that ferrous sulphate, after conversion to sulfide by bacteria in the colon, absorbs arsenic and assists safe excretion.   The evidence for these remains indirect, and there may be (as suggested above) competing adverse effects.  Only good epidemiology can tell.

UNU/BUET meeting

Discussion of technologies in May 2001,
primarily in the context of Bangladesh,  in the following talks which can be downloaded:


top of page


Partial List of Projects both Govt. and non-Govt from M.L.R.Chowdhuri's book

Two reports on 4 small scale systems (
READ-F, SONO 45-25, Sidko and MAGC/ALCAN). are available: one from GMU  and a  poster from OCETA .

Early reviews of Arsenic Removal Technologies by Susan Murcott of MIT:
1999 paper, 2000 abstract

Review of arsenic removal by U.S. EPA

Early Finnish Comparison of various test methods
Finnish review of arsenic removal from groundwater

Small Systems

SONO Filter, a modification of the 3 jar Kalshi filter, developed by Dr Hussam in USA and extensively used in Bangladesh particularly near Kushtia .  His brothers Abul Munir, of Kushtia, and Abul Barkat of the University of Dhaka help to deploy it in Bangladesh.  As noted above it has been approved by the Government of Bangladesh.   It costs approximately $30. 

        Tel:071-61335,61909           Mob:0171-275041             Fax:088-071-61235
We link here to several pdf files about using the filter.
Paper by Khan et al. abut the filter

 As filtration pictures.pdf
 Sono Filtering 4000 ppb As.pdf
Abul Hassam, inventor of the SONO filter has won the $1,000,000 Grainger Challenge Gold Award for 2007
The SONO filter by itself does not grow bacteria as shown in tests  by
Village Education Resource Center (VERC), B-30, Ekhlas Uddin Khan Road,Anandapur, Savar, Dhaka-1340, Bangladesh .

Arup K. SenGupta, of Lehigh University and colleagues  John E. Greenleaf, Lee M. Blaney, Owen E. Boyd, Arun K. Deb,
and the nonprofit organization Water For People have developed and colleagues at Bengal Engineering College in Howrah, West Bengal, have installed alumina filter systems for $1250 for 300 households or $1 per person  Their detailed paper of the results of follow up on over 150 medium sized systems seems convincing.   They were awarded The Grainger Challenge  Silver award for 2007 of $200,000

The Children's Safe Drinking Water Program
at Procter & Gamble Co. (P&G), Cincinnati, receives the Grainger Challenge Bronze Award of $100,000 for the PUR™ Purifier of Water coagulation and flocculation water treatment system.

The detailed report by the organization  BETV-SAM set up by the Bangladesh Government to approve such devices is now available on the BAMWSP website

Javed Iqbal, Ho-Jeong Kim, Jung-Seok Yang, Kitae Baek, and  Ji-Won Yang. Removal of arsenic from groundwater by micellar-enhanced ultrafiltration (MEUF).Chemosphere, July 31, 2006.

Central Electrochemical Research Institute (CECRI), Karaikudi, India with the sponsorship of Department of Science and Technology (DST),New Delhi, India has developed a Domestic 2A capacity Electro Arsenic Purifier for Drinking Water, which can treat 2L of drinking water per one hour. This unit will reduce the arsenic level from 3ppm to 20ppb (WHO standard). This can also be operated with the use of Solar Energy. The Novelty of the Arsenic Purifier is this will removal both

arsenite and arsenate with high efficiency (reduce to 10ppb level). CECRI also developed a Community model Electro Arsenic Purifier for Drinking water, which can treat 40L of drinking water per one hour.The cost of the one 2A Arsenic Purifier is Rs.6,000. The cost of treatment of water is 3 paise.Those who are all interested may contact:
Electroinorganic Chemicals Division
Central Electrochemical Research Institute
Karaikudi – 630 006
Phone: 91 4565 227550 – 227559; Fax: 91 4565 227779Mobile: 9442552441
Email: svdevan_2000 @, vasudevan65 @

MAGC/ALCAN This is uses activated alumina and a a qualitatively different system from most of the ones in use.   It will not suffere from the problems facing iron filters in the Bangladesh environment.   It was favorably reviewd by Akins in 2001and by NAISU in 2003, and it has been approved by  the BETV program Government of Bangladesh,  although the final approval certificate appeared with the usual bureaucratic speed.     Mr M. Saber Afzal claims that it is the cheapest system with a cost of Taka 1,950 ($32,50)  which includes everything.    It is reported to have been well reviewd for the bGrainger Challenger award, but did not make the final cut.   It does not seem to be widely used for reaons which are unclear..

Paul Friot, of Friot Corporation, Ayer, MA, USA has US patent 6,368,510 B2 for a "Method and Apparatus for the Removal of Arsenic from Water" using a two stage process:  manganese greensand oxidizer to convert arsenite to arsenate,  followed by an anion exchange resin. 

Dr Ashok Gadgil from Lawrence Berkeley Labs is developing a filter with coal ash

Susan Murcott at MIT has developed a sand filter called the KANSHAN filter  and has deployed it in Nepal.

Australians are developing a solar energy operated
distillation unitwhich will remove arsenic and many other pollutants.

Calgon Carbon introduces As removal systems

Silver Ceramic Water purifiers as used in Nepal:  (Nepal file)  (local file)

Recommendations for water supply in arsenic mitigation: a case study from Bangladesh. B. Hoque, AA Mahmood, M. Quamruzzaman et al. Public Health (2000), 114, 488-494

A Simple Household Device to Remove Arsenic from Groundwater and Two Years Performance Report of Arsenic Removal Plant for Treating Ground Water  with Community Participation.
  School of Environmental Studies, Jadavpur University, Calcutta-700032, India

Ferric Oxydioxide and Settling by Dr. Richard Anstiss of New Zealand and Professor Mustaque Ahmed (being tested in Bangladesh) procedure presented by Dr. Anstiss at Remediation Conference at DCH, Dhaka, Dec. 14 1998

RedoxTreatment of Groundwater to Remove Arsenic by Biorem International, Inc.

Removal of arsenic from drinking water with enhanced hybrid aluminas and composite metal oxide particles by B. Kepner, J. Spots, E. Mintz,J. Cortopassi, P. Abrahams, C. Gray, S. Mathur

A Permeable Grog for a Low Cost Water Purifier

A review of the SOS procedures for helping the villagers

BUT  be warned by the 6th report from Jadavapur University

Larger systems

ADI have another large scale removal device:   "ADI's MEDIA G2"

Membrane distillation

A Swedish Group with a new water purification technology called membrane distillation. It is able to remove all arsenic 3 and 5 completely. It has been tested at Sandia National Laboratory,  Texas University in El Paso, and in Sweden. It costs roughly what all advanced systems cost but has three advantages:
    1    Removes arsenic completely,
    2    Requires very little maintenance or component replacement,
    3    If waste heat is available, the cost of the water is very low indeed
So far we only have a description in Swedish .

SORB 33 Arsenic Removal Systems , by Severn Trent Services.

At the 5th International Arsenic Conference in San Diego, the purification systems successfully used in Vietnam (particularly in Hanoi) were described.

Apyron Technologies, formerly as Project Earth Industries, Joint Venture partners with RPM, Marketing Pvt. Ltd.
Press release 1 Press release 2

Pure Safe Water Solutions have extensive experience in water purification systems for populations of 1,000 to 10,000 people. They have added the Apyron system to enable them to remove arsenic.

August  2000 Lecture by Matt Simmons on his remediation option.
Matt Simmons' page , with a copy of the patent and the report done on mine water.

Arsenic Remediation Technology (AsRT) Environmental Research Institute (Nikos Nikolaidis, Jeffery Lackovic, Gregory Dobbs, and Larry M. Deschaine). In situ and ex situ remediation and treatment technique for soil/sediment and water. For a good description see the article 18 Mar 98: "Filter cleans arsenic tainted water ," at Environmental News Network website. (tested in the USA)

Department of Chemistry, New Mexico State University Remediation Of Arsenic Using Ferrate

Division of Land and Water Resources Spodic material for in situ treatment of arsenic in ground water

SUBRA , Copper, Chromium And Arsenic removal from tannery and timber treatment effluents

Arsenic Solutions Inc. combine skills from many groups

Water Treatment Methods by Martin Wegelin, Abdul Motaleb et al .

SODIS - an arsenic mitigation option?

SORAS - a simple arsenic removal process

Harbauer Environmental Technology
by Harbauer GmbH & Co KG

Enviro-Main Filter Inc.

HVR arsenic project -development of manufacturing capability in India to produce arsenic removal equipment.

Barry Rosen's web site

"Oxidation/direct filtration technology for arsenic, manganese, and iron in ground water" - Industry Canada Environment Affairs Branch and ADIInc.

Australian CSIRO remediation methods

"Australian science tames arsenic pollution" -

Media release, Australian Nuclear Science and Technology Organization (ANSTO)

Info & products related to solar distillation.

"Solar Water disinfection Technologies"

"Lo-tech patented arsenic removal system" Solar Purification Company Inc.

Arsenic Removal by Enhanced Coagulation and Membrane Processes (paper from Janet Hering)

Use of chitostan derived from clam shells

HYDRO-Solutions and Purification This arsenic removal system was designed to remove arsenic from Alaskan mining wastes. It is claimed by its' proponents to be the most inexpensive (both capital & recurrent costs) process for commercial, industrial, and municipal arsenic removal. They also have a selenium removal methodology."

Purification technology by Krudico

Countertop  Water Distiller

Osmosis System for removal of arsenic

Biological process for removal

Metals and Arsenic Removals Inc (MARTI)

Pollard Industries have a system involving reverse osmosis and filtration to bring mine waters with 500 ppb of arsenic down to 1 ppb.

Please provide any other useful information to

Will you Help?

    Various Charitable organizations are helping to bring pure water to Bangladesh and SE Asia.   This webmaster suggests  that you financially support one or all (any currency) and airline frequent flyer coupons gratefully accepted:

(or direct link
SOS-Arsenic has its update on their program
Another  NGO providing dugwells in India
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