QUALITY AND SUITABILITY OF GROUND WATER FOR DRINKING PURPOSES IN THE WESTERN FRINGE (PERI-URBAN) OF KHULNA CITY, BANGLADESH Study Team: Coordinator Professor Dilip Kumar Datta, Ph.D Environmental Science Discipline, Khulna University, Khulna-9208 Supervisor Masudur Rahman Assistant Professor, Environmental Science Discipline, Khulna University, Khulna-9208. Research Intern Md. Muhyminul Islam B.Sc. Student, Environmental Science Discipline, Khulna University, Khulna-9208 with Khondakar Arifuzzaman MS Graduate, Environmental Science Discipline, Khulna University, Khulna-9208 Project Water Security in Peri-Urban South Asia: Adapting to Climate Change and Urbanization December 2011
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QUALITY AND SUITABILITY OF GROUND WATER FOR DRINKING PURPOSES IN THE WESTERN FRINGE (PERI-URBAN) OF KHULNA CITY, BANGLADESH
Study Team: Coordinator Professor Dilip Kumar Datta, Ph.D Environmental Science Discipline, Khulna University, Khulna-9208 Supervisor Masudur Rahman Assistant Professor, Environmental Science Discipline, Khulna University, Khulna-9208. Research Intern Md. Muhyminul Islam B.Sc. Student, Environmental Science Discipline, Khulna University, Khulna-9208 with Khondakar Arifuzzaman MS Graduate, Environmental Science Discipline, Khulna University, Khulna-9208
Project
Water Security in Peri-Urban South Asia: Adapting to Climate Change and Urbanization
December 2011
ABSTRACT
This study has conducted to assess the quality and suitability of groundwater for drinking purpose in peri-urban area of Khulna City which is situated in the south-western part of coastal Bangladesh. To complete this research work, 20 ground water samples of 10 shallow aquifers and 10 deep aquifers, were collected from 5 different sampling spots which are located on the both banks of the Mayur River. The analysis reveals that the chemical composition of the groundwater in this area is variable, with electrical conductance ranging from 813 to 9800 µs/cm. The pH values range from 7.02 to 8.44. Most of the groundwater is weakly alkaline. Higher value of electrical conductivity (EC) and concentration of sodium ion suggest that water quality of shallow aquifer in this locality is quite unsatisfactory and exceeds the standard guideline value of drinking water of DoE, Bangladesh and WHO. But the major parameters concentration of deep aquifers meets the both standards and is quite satisfactory in respect to drinking purposes.
1. INTRODUCTION
1.1 Background of the Study
The quality of drinking water is a powerful environmental determinant of the health of a community. The problem of the quality of water resources in general, and groundwater resources in particular, is becoming increasingly important in both industrialized and developing nation. In developing countries like Bangladesh the essential concerns as regards water resources are their quantity, availability and suitability. Nevertheless, experience in the more highly developed industrial nations tells us that it is necessary, or at least desirable, to adopt modernization that is compatible with the environment, that is, that will have a sustainable impact. When aiming for environmental sustainability, groundwater and surface water play a leading role because they are of fundamental importance to all living things (Fiorucci, 2007).
Although water is the most frequently occurring substance on earth, lack of safe drinking water is more prominent in the developing countries. Groundwater is the main source of water supply throughout the world. Due to increasing world population, extraction of groundwater is also increasing for irrigations, industries, municipalities and urban and rural households day by day. During dry season extensive withdrawal of groundwater for irrigation purpose is lowering the water table in the aquifer and also changing the chemical composition of water quality (for different aquifer chemistry) (Saha et al.,2007).
Land use has significant impacts on ground water quality. Typical observed changes include increased nitrate concentrations and detection of pesticides in agricultural areas (Burkhart and Kolpin, 1993; Anderson, 1993; Keeney and DeLuca, 1993; Bauder et al., 1993; Cain et. al, 1989), increased nitrate concentrations and pesticide detections in residential areas (Anderson, 1993; Geron et al., 1993; Eckhardt and Stackelberg, 1995), and increased nitrate concentrations and volatile organic compound (VOC) detections in commercial and industrial areas (Eckhardt and Stackelberg, 1995) compared to undeveloped land use settings (Haycock and Pinay, 1993; Anderson, 1993). Some mega or big-cities are allocated near shore or the groundwater resources are underlain by salt waters. In these cases excessive groundwater abstraction may force salt water to move either laterally or vertically into the freshwater, so deteriorating groundwater quality. (Megic et al., 2004). The Khulna City Corporation (KCC) in southwest Bangladesh lies on young Holocene-Recent Alluvium of the Ganges deltaic plain in north and Ganges tidal plain in south. The area is composed of coarse to very fine sand, silt and silty clay up to a depth of 300m with peaty soil and calcareous as well as non-calcareous soil at the top (Roy et al., 2005). Vulnerability of coastal aquifers due to saline water intrusion and other anthropogenic pollution is one of the major environmental hazards restricting availability of fresh water in most coastal cities of the world. KCC is one such city where the aquifers are subjected to
marine influence due to intense anthropogenic pressure from within and outside the region (Datta and Biswas, 2004). And within the KCC areas, only 30% of households are under piped water supply, where the rest are self-managed and many of the people face extreme water crisis. For this reason all the peri-urban dwellers along the both banks of the Mayur River are totally dependent on the GW (ground water) sources for drinking and other household purposes. So quality assurance for groundwater has become the most prior concern in this fringe of the KCC. 1.2 Objectives of the study To monitor the physico-chemical and biological characteristics of the GW of the
western fringe of the KCC area; and
To determine the health risk of GW by assessing its suitability for drinking purpose.
2. MATERIALS AND METHODS 2.1 Component One: Problem Identification Groundwater is the only reliable water resource for human consumption throughout the different parts of the country. Moreover when aiming for environmental sustainability, ground-water plays a leading role because it is of fundamental importance to all living things. So it is urgent to monitor and determine the quality and characteristics of the ground water in an area where the community people are mostly dependent on this source of water. 2.2 Component Two: Study Area Selection Studies for the assessment of the GW quality in the KCC area have already been done but particularly in this western fringe are not still done. Virtually there is a possibility of ground water pollution by the polluted water of Mayur River as the aquifers along the banks might be recharged by river water also. The communities living on the banks of this river are directly dependent on groundwater sources for their drinking purposes. For this reason assessing of the quality and suitability of the ground water for drinking purposes in this area study is now a matter of urgency. 2.3 Component Three: Collection of Water Sample 2.3.1 Selection of the sampling locations The study was conducted on the both banks of the Mayur river. The samples were collected from 5 different sampling locations of the both banks of the Mayur river from Rayer-Mahal to Sachibunia at an approximately same distance of 2 Km.
Fig 2.1: Sampling locations (on the both banks of the river)
2.3.2 Number and frequency of water samples From each sampling location ground water samples will be collected for 4 times at an interval of 2 months from August, 2011 to May, 2012. Each sampling location includes 2 deep-tube wells and 2 shallow tube wells on each bank of the river and 1surface water sample from the middle of the river. 2.3.3 Collection methods 2.3.3.1 For physico-chemical analysis It is the most important part of the present study for the degree of accuracy of analytical results. Every possible precaution was taken to obtain a representative sample. Water samples were collected in 1 L plastic bottles. The bottles were washed 6-7 times with household water and then 2-3 times with distilled water and again entering 1-2 ml of 95-98% industrial sulfuric acid with water (for free foreign chemicals in bottles) in to every bottles and sealed well and preserved for one night. After one night preservation, every bottle was properly washed with shaking by water again 6 or 7 times. Then the bottles were dried in room temperature. Before collection the tube well water was pumped out for at least 5 minutes so that the sample could represent the ground water from which the well is fed. The bottle was then sealed by the tapes. Aeration during sampling was avoided as far as possible. From each bank of the river groundwater samples were collected from the tube-wells which are within 150 feet radial distance from the river.
Fig 2.2: Distance of the sampling tube-wells from the river
2.3.3.2 For microbiological analysis The water samples will be collected during the post monsoon using sterile 250ml sized glass sampling bottles. Samples will be transported to the laboratory in ice for analysis. 2.3.4 Present status of water sample collection Water samples for 3 times (shown in red colour) have already been collected and other samples will be collected in the following months (shown in white colour).
Table2.2: Time of sample collection
2.4 Component Four: Analysis of Water Sample
2.4.1 Parameter selection To measure quality of the collected sample the following tests were performed in respect to health hazard in the ground water of the study area.
Table 2.3: Selected Physico-chemical and Biological parameters for analysis
No. Types Parameters No. Parameters a. Physical i. Temperature
ii. pH iii. EC (Electric Conductivity) iv. TDS v. DO
b. Chemical Cations i. Na+ ii. K+ iii. Ca2+ iv. Mg2+
Anaions i. Cl- ii. HCO3- iii. SO42- iv. PO43- v. NO3- vi. H4SiO42-
c. Biological i. Total Bacterial Counts (TBC) ii. Total Coliform Counts (TCC)
2.4.2 Analytical procedures
For physical, chemical and biological analysis of those water samples a number of sophisticated instruments were used and following established world recognized analytical methods were followed (Table 2.4).
Table 2.4: The methods/instruments, book references used to measure the parameters
2.4.2 Present status of water sample analysis Groundwater and surface water samples of two times have already been analyzed and third samples are being analyzed in the laboratory following the above (Table 2.4) methods or instruments.
Parameters Unit Methods /Instruments References Temperature o
C Centegrade Mercury Thermometer Ramesh and Anbu, 1996 And APHA, 1992
pH - Microprocessor pH meter (HANNA instruments, pH
211) EC µs/c
m TDS meter (H1-9635, portable water proof Multirange Conductivity/TDS meter, HANNA)
TDS ppm TDS meter (H1-9635, portable water proof Multirange Conductivity/TDS meter, HANNA)
Salinity ppt Salinity meter DO mg/l DO meter Ca2+ mg/l Titrimetric method Ramesh
The quality of groundwater is assessed by analyzing the composition of the groundwater and
the mechanism which govern its chemistry. The chemical composition of groundwater
samples in the study area are shown in the following tables (Table 3.2 and Table 3.4).
Table 3.1: Physical parameters of samples in the month of August, 2011 (Sample: 01)
Note: S₁R₁= Sample of Reyermahal, S₁S₁= Sample of Shonadanga, S₁G₁= Sample of Gollamari S₁M₁= Sample of Mohammadnagar, S₁C₁= Sample of Sachibunia. * Red Color marks exceed the recommended limit for drinking water.
Sample ID Type of Tubewells
EC (μs)
TDS (gm/L) pH DO (mg/l)
Temp ( C)
F1 F2 S₁R₁ Deep 1300 0.909 0.649 8.19 1.5 25.4 S₁R₂ Deep 1060 0.743 0.531 8.08 1.3 25.4 S₁R₃ Deep 1093 0.764 0.546 7.11 1.0 25.4
Table 3.3: Physical parameters of samples in November, 2011 (Sample: 02)
Note: S₁R₁= Sample of Reyermahal, S₁S₁= Sample of Shonadanga, S₁G₁= Sample of Gollamari, S₁M₁= Sample of Mohammadnagar and S₁C₁= Sample of Sachibunia. * Red Color marks exceed the recommended limit for drinking water.
Sample ID Type of Tubewells
EC (μs)
TDS (gm/L) pH DO (mg/l)
Temp ( C)
F1 F2 S₁R₁ Deep 1250 0.875 0.625 8.19 1.5 28 S₁R₂ Deep 986 0.688 0.492 8.08 2.0 28.2 S₁R₃ Deep 1055 0.738 0.527 7.11 2.9 28.6
Drinking water quality in respect to consumer health safety refers to that water which is free from any potential health hazard to the consumers. To assess the suitability of groundwater for drinking purposes, in this study two standards, namely the WHO (World Health Organization) and Bangladesh standards were considered to compare with the analyzed data (Table: 3.1 & Table: 3.2) for different parameters.
3.2.1 Description of the Physical parameters
Temperature has no health significance (EPA, 2001) and generally, it is climatologically influenced (in the absence of thermal discharges). Temperatures in all samples were within the standard both in August and November, 2011.
The pH, physical characteristic of all waters or solutions, has no health significance except that extreme values will show excessive acidity or alkalinity, with organoleptic consequences (EPA, 2001). pH in all samples were within the both standard (Table 3.1 and Table 3.3).
Electrical conductivity (EC), which has no direct significance on health, reflects mineral salt content of water (EPA, 2001). EC values of all deep-tubewells were within the standards in the month of August and November, 2011 except S2R1 which exceeded the range in the month of November. But all the shallow aquifer groundwater samples exceeded the standards both in August and November, 2011. DO is the natural characteristic of clean waters. The value of DO in all samples was within the standard both in August and November, 2011.
3.2.2 Description of the Chemical Parameters
Sodium is also an essential dietary requirement and the normal intake is as common salt (sodium chloride) in food; daily consumption may amount to 5 grams or more. The main reason for limiting is the joint effect which it exercises with sulphate but too excessive intake can cause hypertension (EPA, 2001). All samples except S₁R₃, S₁Rs, S ₁S₃, S₁Ss, S₁G₂, S₁Gs, S₁M₄, S₁Ms, S₁C₁ and S₁Cs exceeded both the WHO and Bangladesh standard in August and November, 2011. The highest value of sodium may be due to intrusion of saline water into the aquifer system.
Table 3.5: Chemical composition of Groundwater in the month of August, 2011 (Sample: 01)
Note: Red colored values show the exceeding standards for drinking water.
Remark S₁S₃, S₁G₂, S₁C₁ , S₁M₁, S₁M₄, S₁C₁ are within standards
All deep tube-well samples satisfy the standards
Without S₁C₄, & S₁C₂ others satisfy standards
Most of the samples satisfies the standards
Most of the samples satisfy the standards
All samples are within standards
All samples are within standards
All samples are within standards
All samples exceeded the standards
Potassium has no significant health effects except at gross level (EPA, 2001). All samples except S₁C₂, S₁C₄, S₁G₃, S₁S₄, and S₁S₁ exceeded both the WHO and Bangladesh standard in August and November, 2011.
High levels of calcium may be beneficial and waters which are rich in calcium (and hence are very hard) are very palatable. This element is the most important and abundant in the human body and an adequate intake is essential for normal growth and health. The presence of the element in a water supply is beneficial to health because it helps to reduce the heart disease (EPA, 2001). All values Without S₁C₄, S₁C₂ & S₁M₂ were within the standard (Table 3.5 and Table 3.6).
Magnesium is the second major constituent of hardness and it generally comprises 15-20 per cent of the total hardness expressed as CaCO3. Its concentration is very significant when considered in conjunction with the sulphate and it has indirect effects on health (EPA, 2001).The shallow water sample of S₁C₄, S₁M₂, S₁M₃, S₁C₂, S₁G₃ exceeded both the WHO and Bangladesh standard in August and November, 2011. From the reconnaissance survey it was evident that, consumers were suffering from eczema due to use of excess hard water. A suggested explanation relative to hard water is that increased soap usage in hard water results in metal or soap salt residues on the skin (or on clothes) that are not easily rinsed off and that lead to contact irritation (WHO, 2010).
Chloride does not pose a health hazard to humans and the principal consideration is in relation to palatability (EPA, 2001). Without S₁C₄, S₁C₂, S₁M₂, S₁M₃, S₁G₃ others satisfied the Bangladesh standard while most of the samples are exceeding the WHO standard (Table 3.5 and Table 3.6).
Excess sulphate has a laxative effect, especially in combination with magnesium and/or sodium (EPA, 2001). The values were within the standard (Table 3.5 and Table 3.6).
Most importantly, high nitrate levels in waters to be used for drinking will render them hazardous to infants as they induce the "blue baby" syndrome (methaemoglobinaemia) (EPA, 2001). The values were within the standard (Table 3.5 and Table 3.6). Phosphorus occurs widely in nature in plants, in micro-organisms, in animal wastes and so on. It has no significance on health (EPA, 2001). The values were within the standard (Table 3.5 and Table 3.6). Silica is not a water pollutant but excess of silica in groundwater indicates the active degradation of silicate minerals (Appelo and postma, 1993). The silica content of natural water is usually 1-30 ppm. In the study area the concentration of silica varies from 2.9848 mg/L (S₁R₁) to 21.4712 mg/L (S₁M₂) (Table 3.5 and Table 3.6).
4. CONCLUSION
In the present study, the groundwater quality and its chemical composition have been made to characterize the water in the shallow and deep aquifer in respect to community health in the western peri-urban fringe of Khulna city. The groundwater shows a very variable chemical composition, e.g. electrical conductance ranges from 813 to 9800 µs/cm. However, the chemical quality of the water with respect to sodium ion concentration at most sampling points exceeds the WHO and Bangladesh drinking water standards. Magnesium ion concentration in respect to carbonate hardness is high in shallow aquifers. The water is therefore not suitable for laundry. This study confirms that major chemical parameters of groundwater in Khulna meets the Bangladesh and WHO standard and reflect the suitability of drinking and domestic purposes. However, continuous assessment and monitoring is needed to verify the temporal as well as special variability of the groundwater resources in Khulna for water security and public health.
ACKNOWLEDGEMENTS This study is a part of the research project titled “Water Security in Peri-Urban South Asia: Adapting to Climate Change and Urbanization” supported by the International Development Research Centre (IDRC). We are grateful to Professor M.S. Khan, Professor, Institute of Water and Flood Management (IWFM) of Bangladesh University of Engineering and Technology (BUET) for giving the opportunity in joining with this research project and conducting this study. Thanks are given to IDRC for their support in the development of the study. We are particularly indebted to Dr. Dilip Kumar Datta, Professor and Head, Environmental Science Discipline, Khulna University, Khulna for his continuous invaluable assistance during the study.
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