Arsenic contamination and Mitigation in Bangladesh


Water supply in Bangladesh is predominately based on groundwater sources. In the context of very high prevalence of diarrhoeal diseases in Bangladesh, bacteriological quality received priority as a criterion for drinking water supply. Groundwater is free from pathogenic microorganisms and available in adequate quantity in shallow aquifers for development of low cost tubewell based water supply for scattered rural population. Bangladesh achieved a remarkable success providing 97% of rural population with bacteriologically safe tubewell water. This was considered as the largest population coverage by safe water supply in the region. Water is universal solvent and capable of dissolving almost everything to a certain extent but the possibility of having arsenic at high concentration had never been considered seriously in the past. Unfortunately, arsenic contamination of shallow aquifers in many parts of the country has made shallow tubewell water unsafe for drinking.

Fundamental of Arsenic:

  • Arsenic is widely distributed throughout the Earth’s crust, most often as arsenic sulfide or as metal arsenates and arsenides. It is the 20th most abundant element in the earth’s crust.
  • Arsenic is introduced into drinking-water sources primarily through the dissolution of naturally occurring minerals and ores.
  • Most important route of exposure is through the oral intake of food and beverages. There are a number of regions where arsenic may be present in drinking-water sources, particularly groundwater, at elevated concentrations.
  • Arsenic in drinking-water is a significant cause of health effects in some areas, and arsenic is considered to be a high-priority substance for screening in drinking-water sources.
  • Concentrations are often highly dependent on the depth to which the well is sunk.
Identification of Arsenic in Bangladesh:

  • Arsenic in Tubewell water was first Identified in 1993.
  • At Present Prevalence of Arsenic in Drinking Water has been identified in 61 out of 64 Districts of the Country. (Except, Hilly Districts)
  • However the Degree of Contamination varies from 1% to over 90% with an average contamination of 29%.
  • Arsenic in drinking-water is a significant cause of health effects in some areas, and arsenic is considered to be a high-priority substance for screening in drinking-water sources.
  • In 268 (at present 271) out of 463 Upazilas of the country the Problem identified from the Survey of DPHE-UNICEF & DPHE-BGS (British Geological Survey). Survey of DPHE–UNICEF in 198 safe Upazilas identified 12 more Upazilas having arsenic problem.
Health Effect:

  • Excess amount of Arsenic intake above the permissible limit in Human body makes Arsenicosis diseases.
  • Maximum permissible limit for Bangladesh 0.05 mg/l
  • WHO guideline value = 0.01 mg/l
Fact from WHO Guidelines

  • Provisional guideline value 0.01 mg/litre (10 µg/litre). The guideline value is designated as provisional in view of the scientific uncertainties.
  • Occurrence Levels in natural waters generally between 1 and 2 µg/litre, although concentrations may be elevated (up to 12 mg/litre) in areas containing natural sources.
  • Basis of guideline: There remains considerable uncertainty over the actual risks at low derivation concentrations, and available data on mode of action do not provide a biological basis for using either linear or non-linear extrapolation
  • Limit of detection 0.1 µg/litre by ICP/MS; 2 µg/litre by hydride generation AAS or FAAS
  • Treatment achievability: It is technically feasible to achieve arsenic concentrations of 5 µg/litre or lower using any of several possible treatment methods. However,this requires careful process optimization and control, and a more reasonable expectation is that 10 mg/litre should be achievable by conventional treatment, e.g., coagulation.
Scale of the Problem:

  • Mostly Shallow Tubewells are contaminated 29% of the sampled Tubewells are found contaminated nationally.
  • Deep Tubewells (>150m depth) are generally safe.
  • Survey findings indicated that irrigation is not the major cause of the Ground water Arsenic Problem (DPHE-BGS Study, 2000).
  • 30-35 millions people are expected to be exposed to Arsenic contamination.
  • The worst affected Districts:





Health Hazard:

Primary stage Secondary stage Final stage



Arsenic Mitigation activities

  • Awareness Building.
  • Testing of Tube well Water.
  • Marking of Contaminated and Uncontaminated ube wells.
  • Providing Alternative Water Supply Options.
  • Patient Identification & Management

Awareness Building

Disseminate Knowledge about arsenic posioning through multi-media channels.
  • TV
  • Inter Personal Comm.
It is not contagious

Testing of Tubewell by Field Kits.

Chemical Used
  • KI
  • SnCl2
  • Zn
  • HCL

Green <0.05mg/l

National Screening Summary

  Upazilas screened: 270
  Total tubewells (TW): 5.07 million
  TWs screened: 4.95 million
  TWs found green: 3.50 million (71% of screened)
  TWs found red: 1.44 million (29% of screened)
  Estimated total TWs: approx. 8.61 million nationwide (90.3% private)
  Nationwide tubewell contamination: approx. 20%
For detail information visit web site

Arsenic by well type

Based on data in 15 upazila study

Four Steps of Mitigation

A. Awareness Building : DPHE, DGHS and NGO Partner.
B. Testing of tubewell and marking of contaminated & uncontaminated tube well : DPHE with NGO Partner
C. Patient Identification and management : DGHS
D. Providing alternative water supply option: DPHE with NGO partner

Alternate water supply option

The following option were identified as Arsenic mitigation option. These are categories as two group: a) Non Chemical b) chemical.

Non Chemical Option

Pond Sand filter : Treat pond water

Ring Well/ Dug well

Oldest method to abstract water by digging a hole and using bucket with rope. Now it is upgraded by setting hand pump and covering the top of the well.

Mostly suitable in shallow depths above the contaminated aquifer. But it has a secondary risk of bacteriological contamination.

Dug well should be installed with safety from sanitation where deep tubewells are not successful.


Ring Well/ Dug Well

Chulli Water Purifiers (CWP)

  1. Innovative household treatment
  2. Waste heat from oven »» pasteurization
  3. Low Cost (450 Tk)
  4. High flow rate (30 lph)
  5. Three pilot phases: 2,640 installed

chulli water purifier


Village Piped Water Supply

Surface water or Ground water source will be used. Existing Irrigation well which is arsenic safe can also be used where available .


Chemical option:

Surface water or Ground water source will be used. Existing Irrigation well which is arsenic safe can also be used where available .

SIDKO (Community) Read-F (household) AlKAN(household) SONO (household)


  • To date 106,939 point source & 97 piped water ( source : APSU report)
  • Overall alternate options covber 38% in affected Upazilas.



Rapid Assessments of Arsenic Mitigation Option


  • ITN-BUET conducted a health risk assessment of different non-chemical alternative options with the assistance of APSU, a DFID funded government project.
  • Four options namely Dug well, PSF, Rain water Harvester and Deep Tube well were
  • Microbiological contamination was very high in Dug wells and PSFs.
  • More than 90% dug wells and PSFs were found to contain TTC
  • Microbiological contamination was least in Deep tube wells.
  • Only 8% Deep tube wells were found to contain TTC
  • Microbiological contamination was found moderate in rain water harvesters.
  • 40% - 60% rain water harvesters were found to contain TTC.
  • No or very low chemical contamination was found in Rain water harvesters

Conclusion on Alternative water Options


  • No universal alternative options to provide safe water to the people.
  • Neither ground water nor surface water can be chosen blindly as safe water source.
  • Appropriate technology is to be selected considering both risks of chemical and microbiological contamination, affordability, user-friendly O&M, year round availability etc.




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