How can we best provide safe water in Bangladesh?
Some responses


1- The scientists at Columbia University have published a comment that can be accessed here.

2- Dr. Meera M Mira Smith of the University of California and worker in West Bengal writes:

3.  John MacArthur of University College London Comments below:

4.  Richard Wilson of Harvard  University . comments: 


  

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  1-

  

   The scientists at Columbia University have published a comment that can 
be accessed here 

  

  
  http://www.earthinstitute.columbia.edu/news/2003/story07-18-03.html

  
  

  

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  2-

   

   Dr. Meera M Mira Smith of the University of California and worker in West
 Bengal writes as follows:

   

   Future of the tube wells: The 15,000 tube wells, depending on their depth,
 may get contaminated with arsenic within one year followed by installation
 of filters to remove the arsenic in the water. Within the following year,
 these filters will be labeled as "out-of-order" due to improper management,
 and back to square one. What a waste of funds! 

   

   It is indeed extremely difficult to say what is the best option because 
the  options need to be suitable for the specific area.  

   

   According to my opinion the best, long-term option is distribution of
water  by pipelines stored in the overhead tanks. The water from the third
aquifer  needs to be accessed very cautiously, to avoid cross contamination,
and pumped  up to overhead tanks. 

   

   Until the implementation of such huge projects to cover the whole country 
 the best option, for the interim period, is harvesting of rainwater. Awareness, 
 training and management are the three main components to run these projects 
 successfully in the beginning. The objective of Project Well is to make the
 dug well project sustainable at the village level. To make it sustainable, 
 a team of three field staff has been involved who would train and supervise 
 the users of 26 dug wells only for one year. 

   

   To increase the crop production during the period of green revolution
methods  like workshops organized by local NGOs, programs broadcasted on
the radio  mainly for the farmers (chasi bhaid'eyr bolchhi) were/are used
to promote  the use of high yield variety of seeds and the use of fertilizers
and pesticides.  These informative methods can be used for training the users
of dug wells.  As the farmers know today when to apply fertilizers and pesticides
to their  crops, similarly the dug well users would know how to maintain
their dug wells, community or private, in few years. Rome was not built in
one day. 

   

   Suggestions for the schools: 

   a) If there is a pond nearby, preserve it and install a bacteria removal 
 filter before supplying water to the school tap. Many families in the villages 
 of the district of South 24 Parganas, West Bengal, use pond water >for 
 cooking that constitutes 25% of their daily water usage. 

   b)Try excavating a couple of shallow dug wells using the guidelines used 
 by Project Well and test the water for arsenic, quarterly. (Details are available
 on the web site). The arsenic level in water of 5 concrete, shallow dug
wells provided by Project Well were monitored for one year (ending July 2003)
and it was found that in all the five wells arsenic level was lower than
50 PPB throughout the year except for one which increased to more than 100
PPB in the driest months of April and May. During this period the consumers 
were requested to collect water from other sources that are located far. According
to the users, it is worth having an arsenic safe water source that would
provide water for ten >months rather than having no source at all in their
locality. Project Well is trying to assess the cause of the increase in arsenic
in this particular well. Suggestions from the experts would be a great help.
The bacteria can be removed by filtering the water if the use of Theoline,
a disinfectant, is not preferred.

   c) During the monsoon period rainwater can be collected for drinking.
There  are several methods practiced in many parts of the world. If none
of the rainwater harvesting methods can be implemented then properly installed
deep tube wells (refer to John McArthur's suggestion circulated to arsenic
crisis group on 14th July,2003) can be an option. But extra caution need
to be taken in detecting the level "deep". It is also important to strictly
supervise the drilling, insertion of the pipes, to avoid cross contamination
and detecting the safe depth.

   

   Use of arsenic removal filters is the last option if none of the above 
works.  There are problems with all methods suggested so far for the long-term 
disposal  of arsenic waste. The 'green' disposal method recently developed 
by Naval  Materials Research Laboratory ( NMRL), DRDO, Ministry Of Defence, 
Shil-Badlapur  Road, Addl. Ambernath-421506 "A SIMPLE AND ENVIRONMENTALLY 
SAFE DRINKING WATER FILTER FOR ARSENIC REMEDIATION" sounds very good but who
knows that the construction industries that would use the non-leachable cement
blocks made >from the arsenic sludge would not face the same fate as the
asbestos industries are facing today. 

   

   Use of a checklist in prioritizing the methods suitable for the schools 
based  on its location would be a good start.

    

   Thanking you.

   

   Dr. Meera M Hira Smith 

     


  3.   Comment by John Macarthur, University College London

   

   Does not the answer to the question "how can we provide safe water" depend
 on the area of the country under consideration and include the following? 
 

   

   Reliance on:

   

   1] The 75% of shallow wells that are not polluted with arsenic,

   2] Deep wells,

   3] Traditional dug wells, modernised as appropriate, and

   4] Rainwater harvesting.

   

   The last may be a good option for schools, where the children might incorporate
 a knowledge of, and maintenance of, the water system as part of  their
 curriculum.  Certainly, deep wells, properly constructed, have much
to offer, and this is an option employed much in West Bengal (my definition 
 of  a "deep" well  is a well completed entirely in sands beneath
 the Holocene/latest Pleistocene transgressive surface).  

   

   Provided the wells are constructed so as to prevent leakage between the 
upper  and lower aquifers, it is likely that they will be free of arsenic 
(and other undesirables) for the foreseeable future, particularly if they 
are screened several tens of metres below the top of the deep aquifer. There 
are several  reasons why this should be so; they range from geochemical considerations 
 to 

   an observation, based on the DPHE database (DPHE 1999, 2001) and summarised
 in the accompanying table, that deep wells seem to remain free of arsenic. 
 Isolated instances of pollution in deep wells have ready explanations in 
casing failure, contamination, leakage etc.

   

   Area       No.    Age, 
range   As, range  Depth, range  % Shallow wells

              DTW       
 (y)       (ug/L)         
 (m)        > 50 As ug /L

   Chandpur    4        
2-  3         0-6        
 221-269         98

   Lakshmipur  6        3-10         
 0-8        183-318         
 64

   Noakhali    6        
5-15          2-10       
246-292          79

   

   

   No doubt all of this has been gone over many times.  What is not
often   stated is that 75% of wells in the Bengal Basin are doing the
job for which  they were intended - providing good quality water for public
consumption:  proof enough that, in the right place and at the right depth,
the tubewell  has a future in water supply in the area.

   

   Sincerely,

   

   John McArthur

     



 
  

 

   4.  Richard Wilson of Harvard  University comments:

  

  
   At first sight it seems obvious that one should use deep wells (into an 
arsenic  free aquifer) for drinking and continue to use shallow wells for 
irrigation.    (If one used deep wells for everything one would soon 
reduce the ability  to get water therefrom).   But I am very nervous 
about any large program  to indiscriminantly install new tube wells.  It 
is likely that 90% of  them would be sunk by local people.  If cement 
were provided for grouting  them, the cement might well be used for the more 
urgent needs such as laying  a kitchen floor or otherwise fixing up a house. 
 Failure to grout even   20% of the proposed wells would lead to 
disaster as arsenic laden water  from the upper aquifer leaked into the lower 
one    The disaster  would be compounded by the fact that measurement 
of arsenic in the field is still very inaccurate, and very infrequent.  It 
might be a few years  before the realization set in that Bangladesh had once 
again taken the wrong  route on the basis of foreign advice.  The crisis 
is not merely one of arsenic but of capacity of the villagers to cope with 
the problem (as outlined in the report by Ms Patel listed in the references). 
   It is for this reason that DCH now recommend for more general 
use the use of sanitary dug wells which have been shown to be arsenic free. 
 I agree.   Measuring for coliform bacteria, to check on the sanitary 
conditions, is much more reliable than measuring arsenic concentrations, and
cheaper.    Sanitary dugwells cost about twice as much as a deep tube
well, but that cost may well be worthwhile.

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