Abstract

Safe water is essential for life. Consumption of arsenic and manganese contaminated water poses a range of health effects to humans. Physico-chemical and bacteriological characteristics of groundwater at five administrative upazillas in Kushtia District, Bangladesh, have been studied to evaluate the potability of water for drinking purpose from 32 randomly selected tube wells (TWs). APHA (2012) standard analytical methods were applied for analyses of the physico-chemical and bacteriological parameters of the water samples. Arsenic, iron, and manganese content were analyzed by atomic absorption spectroscopy (AAS). The investigated parameters of water samples were found as pH 6.81–8.12, electrical conductivity (EC) 520–1,995 μs/cm, total dissolved solids (TDS) 357.8–1,372.6 mg/L, chloride 10–615 mg/L, total hardness 285–810 mg/L, arsenic (As) 0.001–0.098 mg/L, iron (Fe) 0.04–1.45 mg/L, manganese (Mn) 0.01–6.32 mg/L. About 56.25% of TWs were highly contaminated with fecal coliform (FC) and 68.75% were found to be contaminated with total coliform (TC). Results were compared with World Health Organization (WHO) and Bangladesh Drinking Standards (BDS). The concentrations of water quality parameters are much higher as compared to WHO and BDS standards. This may cause acute public health risks and make water unsuitable for direct human consumption without treatment.

INTRODUCTION

Water is the most fundamental commodity to the survival of life (WHO 2011a). Therefore, major requirements are not only to have sufficient supply, but also to have quality water that must be considered safe for human consumption (Amanatidou et al. 2007). This is a vital promise for public health and also essential to environmental security and sustainable development certainty (Eze & Madumere 2012). Groundwater is the world's largest source of fresh potable water (Howard 1997). Worldwide it provides an estimated 1.5 billion people everyday (DFID 2005) and is a fundamental resource for meeting rural water demand (MacDonald & Davies 2002; Harvey 2004). With ever-increasing water demand, the preference for most people in rural areas of Bangladesh is for groundwater and to abstract water through tube wells (TWs) for industrial, agricultural, and domestic use. However, the quality of groundwater resources varies from place to place, sometimes depending on seasonal changes (Trivede et al. 2010; Vaishali & Punita 2013; Juwarkar 2015) and the types of soils, rocks, and surfaces through which it flows (Thivya et al. 2014). As groundwater flows through sediment metals from different sources can be dissolved and may later be found in high concentrations in the groundwater (Moyo 2013). Human activities can influence the composition of groundwater with the use of chemical fertilizer and microbial substances on the land surface and into soils, or through injection of wastes directly into groundwater. Industrial discharges (Govindarajan & Senthilnathan 2014) and urban activities can affect groundwater quality. Thus, pesticides and fertilizers applied to lawns and crops can coagulate and migrate to water tables which affect the physical, chemical, and bacteriological quality of water.

In rural areas, the familiar type of sanitation, pit latrines, pose a great risk to the bacteriological quality of groundwater. A septic tank can introduce bacteria into water. Poor sanitary completion of TWs may lead to contamination of groundwater. Proximity of some TWs to solid waste dumpsites and animal droppings being littered around them (Bello et al. 2013) could also contaminate the quality of groundwater.

Residents, especially in rural areas, depend on groundwater resources. The quality of water from these sources is unpredictable; usually in some areas it may contain high quantities of arsenic (Von Brömssem et al. 2014) which is of particular concern (Van Vuuren 2013) to us. In some articles, high levels of iron, manganese and hardness problems in groundwater elsewhere have also been reported (Rahman et al. 2016). As far as we are aware, no report has been published concerning the physico-chemical and bacteriological properties of these areas.

The objective of this research was to monitor the water quality of this area for human potability concerning physico-chemical and bacteriological contaminants and possible impact on human health.

MATERIALS AND METHODS

Study area

Kushtia district is located in the Khulna administrative division of the western part of Bangladesh. It is bordered by the mighty Padma River to the north, Jhenaidah district to the south, Rajbari district to the east, Meherpur, Chuadanga districts and Nadia and Murshidabad districts of West Bengal (Indian State) to the west. The latitude (N) and longitude (E) position of each location was confirmed by GPS Meter (Garmin eTrex 10) reading which is given in Table 1.

Table 1

Location, latitude, longitude, and sample ID of the sampling points

Sl. no. Upazilla Union Village Latitude (N) Longitude (E) Sample ID Sample collection date 
Kushtia sadar Jhaudia Ashtanagar 23°46′58″ 89°04′47″ D-1 17/09/2017 
Kushtia sadar Jhaudia Badunathpur Matpara 23°45′58″ 89°04′25″ D-2 17/09/2017 
Kushtia sadar Alampur Kathulia 23°50′44″ 89°05′36″ D-3 17/09/2017 
Kushtia sadar Alampur Alampur Karigar Para 23°49′43″ 89°05′52″ D-4 17/09/2017 
Kushtia sadar Barakhada Mangalbaria 23°55′03″ 89°06′48″ D-5 17/09/2017 
Kushtia sadar Barakhada Mongolbaria 23°55′02″ 89°06′57″ D-6 17/09/2017 
Kumarkhali Chandpur D-Chandpur 23°45′56″ 89°11′16″ D-7 18/09/2017 
Kumarkhali Chandpur Jongoli 23°45′27″ 89°09′02″ D-8 18/09/2017 
Kumarkhali Jagannathpur Doyrampur 23°53′30″ 89°15′30″ D-9 18/09/2017 
10 Kumarkhali Kaya Baniapara 23°55′15″ 89°'09′35″ D-10 18/09/2017 
11 Kumarkhali Panti Krishnopur 23°47′32″ 89°'13′43″ D-11 18/09/2017 
12 Kumarkhali Chapra Varora 23°51′00″ 89°12′07″ D-12 18/09/2017 
13 Khoksha Khoksha Rotonpur 23°49′17″ 88°16′27″ D-13 20/09/2017 
14 Khoksha Osmanpur Komorvog 23°46′31″ 89°15′29″ D-14 20//09/2017 
15 Khoksha Osmanpur Komorvog 23°46′55″ 89°16′09″ D-15 20//09/2017 
16 Khoksha Janipur Biharea 23°45′33″ 89°18′50″ D-16 20//09/2017 
17 Khoksha Ambaria Ambaria 23°52′30″ 89°20′30″ D-17 20//09/2017 
18 Khoksha Gopagram Khoddosadhua 23°51′20″ 89°18′09″ D-18 20/09/2017 
19 Khoksha Gopagram Boroiechara 23°51′03″ 89°18′40″ D-19 20//09/2017 
20 Khoksha Samaspur Poddojani 23°49′49″ 89°18′35″ D-20 20//09/2017 
21 Mirpur Amla Kuhahbaria 23°53′23″ 88°56′42″ D-21 22/09/2017 
22 Mirpur Chithulia Dhubail 23°58′07″ 88°58′54″ D-22 22/09/2017 
23 Mirpur Bahalbaria Sahabnoger 23°58′06″ 89°02′24″ D-23 22/09/2017 
24 Mirpur Bahalbaria Khadempur 23°58′43″ 89°01′11″ D-24 22/09/2017 
25 Mirpur Fulbaria Mirpur 23°56′03″ 88°59′59″ D-25 22/09/2017 
26 Mirpur Poradaha Ahmmedpur 23°53′19″ 88°03′45″ D-26 22/09/2017 
27 Mirpur Kursha Kursha 23°50′16″ 88°56′59″ D-27 23/09/2017 
28 Mirpur Kursha Essalmaria 23°49′37″ 88°57′13″ D-28 23/09/2017 
29 Mirpur Kursha Essalmaria 23°49′15″ 88°57′11″ D-29 23/09/2017 
30 Bheramara Dharampur S.bhabanipur 23°00′58″ 88°57′40″ D-30 23/09/2017 
31 Bheramara Mokarimpur Fokerabad 24°04′49″ 88°58′57″ D-31 23/09/2017 
32 Bheramara Junaidaha Juniadaha 24°05′27″ 88°55′56″ D-32 23/09/2017 
Sl. no. Upazilla Union Village Latitude (N) Longitude (E) Sample ID Sample collection date 
Kushtia sadar Jhaudia Ashtanagar 23°46′58″ 89°04′47″ D-1 17/09/2017 
Kushtia sadar Jhaudia Badunathpur Matpara 23°45′58″ 89°04′25″ D-2 17/09/2017 
Kushtia sadar Alampur Kathulia 23°50′44″ 89°05′36″ D-3 17/09/2017 
Kushtia sadar Alampur Alampur Karigar Para 23°49′43″ 89°05′52″ D-4 17/09/2017 
Kushtia sadar Barakhada Mangalbaria 23°55′03″ 89°06′48″ D-5 17/09/2017 
Kushtia sadar Barakhada Mongolbaria 23°55′02″ 89°06′57″ D-6 17/09/2017 
Kumarkhali Chandpur D-Chandpur 23°45′56″ 89°11′16″ D-7 18/09/2017 
Kumarkhali Chandpur Jongoli 23°45′27″ 89°09′02″ D-8 18/09/2017 
Kumarkhali Jagannathpur Doyrampur 23°53′30″ 89°15′30″ D-9 18/09/2017 
10 Kumarkhali Kaya Baniapara 23°55′15″ 89°'09′35″ D-10 18/09/2017 
11 Kumarkhali Panti Krishnopur 23°47′32″ 89°'13′43″ D-11 18/09/2017 
12 Kumarkhali Chapra Varora 23°51′00″ 89°12′07″ D-12 18/09/2017 
13 Khoksha Khoksha Rotonpur 23°49′17″ 88°16′27″ D-13 20/09/2017 
14 Khoksha Osmanpur Komorvog 23°46′31″ 89°15′29″ D-14 20//09/2017 
15 Khoksha Osmanpur Komorvog 23°46′55″ 89°16′09″ D-15 20//09/2017 
16 Khoksha Janipur Biharea 23°45′33″ 89°18′50″ D-16 20//09/2017 
17 Khoksha Ambaria Ambaria 23°52′30″ 89°20′30″ D-17 20//09/2017 
18 Khoksha Gopagram Khoddosadhua 23°51′20″ 89°18′09″ D-18 20/09/2017 
19 Khoksha Gopagram Boroiechara 23°51′03″ 89°18′40″ D-19 20//09/2017 
20 Khoksha Samaspur Poddojani 23°49′49″ 89°18′35″ D-20 20//09/2017 
21 Mirpur Amla Kuhahbaria 23°53′23″ 88°56′42″ D-21 22/09/2017 
22 Mirpur Chithulia Dhubail 23°58′07″ 88°58′54″ D-22 22/09/2017 
23 Mirpur Bahalbaria Sahabnoger 23°58′06″ 89°02′24″ D-23 22/09/2017 
24 Mirpur Bahalbaria Khadempur 23°58′43″ 89°01′11″ D-24 22/09/2017 
25 Mirpur Fulbaria Mirpur 23°56′03″ 88°59′59″ D-25 22/09/2017 
26 Mirpur Poradaha Ahmmedpur 23°53′19″ 88°03′45″ D-26 22/09/2017 
27 Mirpur Kursha Kursha 23°50′16″ 88°56′59″ D-27 23/09/2017 
28 Mirpur Kursha Essalmaria 23°49′37″ 88°57′13″ D-28 23/09/2017 
29 Mirpur Kursha Essalmaria 23°49′15″ 88°57′11″ D-29 23/09/2017 
30 Bheramara Dharampur S.bhabanipur 23°00′58″ 88°57′40″ D-30 23/09/2017 
31 Bheramara Mokarimpur Fokerabad 24°04′49″ 88°58′57″ D-31 23/09/2017 
32 Bheramara Junaidaha Juniadaha 24°05′27″ 88°55′56″ D-32 23/09/2017 

Sampling and preservation

The drinking water samples from 32 randomly selected TWs (a tube well consists of a long pipe drilled subsurface or deep aquifer into the earth, with a hand pump attached at the top to obtain water) were collected for physico-chemical analyses in prewashed (with detergent, de-ionized water, diluted HNO3 and completely de-mineralized water, respectively) high density polyethylene (HDPE) bottles from 32 different sources in the region of Kushtia district. All 32 water samples were collected within a week (third week of September 2017). During sampling the weather conditions were dry (temperature was about 25–27 °C). The sampling locations are shown in Figure 1. The water samples were collected in sterilized sample bottles for bacteriological analyses (fecal coliform (FC) and total coliform (TC)) carried out within 4 h after sampling.

Figure 1

Location map of Kushtia, Bangladesh.

Figure 1

Location map of Kushtia, Bangladesh.

Reagent and solutions

Analytical grade reagent chemicals were applied for the preparation of all solutions. Freshly prepared double de-ionized distilled water was used in all experiments. 5.0 M Hydrochloric acid (Sigma-Aldrich, USA), 0.6% sodium borohydride solution (Sigma-Aldrich, USA) reagent, 20% potassium iodide (Sigma-Aldrich, USA) solution as a reductant, inert gas argon (as a carrier gas) for HVG system (determination of As), air-acetylene as a fuel gas for direct flame system (determination of Fe and Mn), commercial grade standard solutions (CRM) of As, Fe, Mn solutions (Fluka-Analytical, Switzerland) were employed during the experiments.

Physico-chemical analyses

The physico-chemical water quality was measured in terms of pH, electrical conductivity (EC), total dissolved solids (TDS), chloride, total hardness, arsenic (As), iron (Fe), and manganese (Mn). All examinations were conducted according to American Public Health Association Standard Methods (APHA 2012).

The pH and EC of water were determined on-site using a multimeter (Model HQ 40d, HACH, USA). The meter was calibrated initially by using two buffer solutions at pH = 4.01 and pH = 7.0 followed by rinsing thoroughly using de-ionized water. The meter was verified after measuring five samples. For EC determination, the meter was calibrated by using standard 1,000 μS/cm NaCl solution and verified after five measurements. pH and EC of the samples were measured while collecting the samples. In the case of TDS measurement, the multimeter (Sension-156, HACH, USA) was calibrated by 1,000 mg/L TDS standard and measured with the same method as EC measurement.

Chloride was analyzed by the standard titrimetric (Argentometric) method (APHA 2012). Here, silver nitrate (BDH, UK) solution (0.0141N) was used as titrant and potassium chromate (K2CrO4) used as an indicator. NaCl was used for the determination of strength of silver nitrate. pH of water was adjusted so that it would fall within 7 to 10 pH units, and 1 mL of K2CrO4 (BDH, UK) indicator solution was added. Then, the obtained solutions were titrated with standard AgNO3 to a pinkish yellow end point. The titrant was standardized and reagent blank value was established (APHA 2012).

Hardness was analyzed by standard ethylene diamine tetra-acetic acid (EDTA) (Merck, Germany, 0.01 M) titration method (APHA 2012). Erichrome Black T (Merck, Germany) was used as a indicator. 25 mL of the samples were diluted to 50 mL by distilled water, and 1 mL of buffer solution (pH = 10) was added in a conical flask, as well as two drops of indicator solution. Then, the solution was titrated with EDTA, until the last reddish tinge disappeared (the solution is normally blue) (APHA 2012).

Arsenic, iron, and manganese were analyzed by atomic absorption spectrophotometric (AAS) method (APHA 2012). First, preparation of calibration curve was done by using working standard solutions of different concentrations from certified reference material (CRM). As (V) is reduced to As(III) using potassium iodide and sodium borohydride reagent to form arsine vapor by the use of carrier gas argon and detect the total arsenic at 193.7 nm wavelength. This process is called hydride vapor generation (HVG). Iron and manganese is analyzed by atomization process (direct flame) creating a flame by the combustion of air and acetylene gas (flame temperature nearly about 2,200 °C) at 248.3 and 279.5 nm wavelength, respectively.

Bacteriological analyses (FC and TC)

Water samples were analyzed immediately after collection for the presence of fecal coliforms and total coliforms using membrane filtration method (APHA 2012). 100 mL from each water sample was filtered through 0.45 μm pore size filter papers. The filters were placed on mFC agar and mENDO agar and plates were incubated aerobically at 45 °C and 37 °C, respectively, for 21 ± 3 h. Blue and metallic sheen (golden red) colonies on MFC agar and mENDO agar plates were purified and used for bacteria identification tests. For all the assays, positive and negative controls were performed (ISO 1986).

Data analysis

Data for physico-chemical and bacteriological contaminants in drinking water samples were recorded and analyzed for pH, EC, TDS, chloride, hardness, As, Fe, Mn, FC, and TC. Mean and standard deviations were calculated from the results of the analysis of the three samples per sampling point. Errors were calculated to ±5%. Results were compared with the Department of Environment (Environment Conservation Rules 1997), Bangladesh and the WHO drinking water standards.

Water quality index (WQI)

WQI indicates the quality of water in terms of index number which represents overall quality of water for any intended use. It is defined as a rating reflecting the composite influence of different water quality parameters taken into consideration for the calculation of WQI. The indices are among the most effective ways to communicate information on water quality trends to the general public or to policy-makers and in water quality management. Mostly, it is considered from the point of view of its suitability for human consumption. In this study, the weighted arithmetic mean method is used for the determination of WQI.

Weighted arithmetic WQI method

The weighted arithmetic WQI method (Yisa & Jimoh 2010; Tyagi et al. 2014; Akter et al. 2016) was applied to assess water suitability for drinking purposes. In this method, water quality rating scale, relative weight, and overall WQI were calculated as per Equations (1)–(3) respectively. 
formula
(1)
where Qi, Ci, and Si indicate quality rating scale, experimental concentration of I parameter, and standard value of i parameter, respectively.
Relative weight was calculated by Equation (2): 
formula
(2)
where the standard value of the i parameter is inversely proportional to the relative weight.
Finally, overall WQI was calculated according to Equation (3): 
formula
(3)

RESULTS AND DISCUSSION

Physico-chemical characteristics

The results of physico-chemical analysis are summarized in Table 2. According to Bangladesh Drinking Standards (BDS), pH of water should be 6.5 to 8.5. Thus, as shown in Table 2, all the water samples are slightly alkaline and in the range of 7.11 to 8.12 except that for sample no. D-1 (6.91) and D-5 (6.81). Hence, the pH of the water in the study area could be classified as suitable for drinking purposes. However, these values do not compromise groundwater quality in terms of human consumption, as they only reflect the geological composition of the ground (Trivede et al. 2010). Extreme values of pH may result in irritation of the eyes, mucous membranes, and skin (WHO 1996). No health-based guideline value is proposed for pH (WHO 1996).

Table 2

Physico-chemical analyses of groundwater samples

Sample ID pH EC (μs/cm) TDS (mg/L) Cl (mg/L) Hardness (mg/L) As (mg/L) Fe (mg/L) Mn (mg/L) 
D-1 6.91 710 488.5 55 290 0.003 0.04 0.09 
D-2 7.11 560 385.3 18 340 0.02 0.04 0.11 
D-3 7.13 612 421.1 97 355 0.001 1.45 0.11 
D-4 7.10 490 337.1 10 423 0.064 0.11 1.94 
D-5 6.81 704 484.3 30 462 0.028 0.16 6.32 
D-6 7.20 690 474.7 48 485 0.079 0.04 0.98 
D-7 7.81 750 516 20 398 0.016 0.1 0.87 
D-8 7.93 620 426.6 19 295 0.004 0.05 0.31 
D-9 7.85 670 461 21 440 0.098 0.05 0.34 
D-10 7.87 720 495.4 24 390 0.001 0.61 0.09 
D-11 7.67 840 578 22 430 0.011 0.39 0.59 
D-12 7.49 1,830 1,259 490 690 0.006 0.07 0.12 
D-13 7.81 960 660.5 55 485 0.005 0.04 0.09 
D-14 7.92 780 536.6 20 392 0.002 0.10 0.09 
D-15 7.73 770 529.8 40 410 0.013 0.05 0.30 
D-16 7.81 800 550.4 58 350 0.005 0.04 0.12 
D-17 7.83 840 578 40 425 0.009 0.05 0.30 
D-18 7.66 890 612.3 30 440 0.02 0.52 4.72 
D-19 7.82 840 578 20 435 0.027 0.04 3.64 
D-20 7.82 830 571 65 410 0.022 0.75 4.93 
D-21 8.11 580 399 20 290 0.001 0.09 0.01 
D-22 7.92 680 467.8 22 395 0.001 0.42 0.01 
D-23 7.54 1,590 1,094 335 740 0.001 0.09 0.01 
D-24 7.48 1,230 846.2 202 505 0.007 0.22 0.01 
D-25 7.85 550 378.4 30 403 0.02 0.09 0.01 
D-26 7.91 520 357.8 21 285 0.007 0.92 0.18 
D-27 7.72 700 481.6 20 401 0.024 0.49 4.05 
D-28 7.63 1,995 1,372.6 615 810 0.002 0.04 0.20 
D-29 7.91 700 481.6 50 380 0.001 0.04 0.01 
D-30 7.72 894 615.1 110 545 0.003 0.81 1.02 
D-31 7.91 660 454.1 20 360 0.022 0.04 0.01 
D-32 8.12 910 626.1 70 392 0.006 0.04 0.10 
WHO (2011a)  6.5–8.5 – – 250 500 0.01 0.3 0.5 
Environment Conservation Rules (ECR 1997)  6.5–8.5 – 1,000 600 500 0.05 1.0 0.1 
Sample ID pH EC (μs/cm) TDS (mg/L) Cl (mg/L) Hardness (mg/L) As (mg/L) Fe (mg/L) Mn (mg/L) 
D-1 6.91 710 488.5 55 290 0.003 0.04 0.09 
D-2 7.11 560 385.3 18 340 0.02 0.04 0.11 
D-3 7.13 612 421.1 97 355 0.001 1.45 0.11 
D-4 7.10 490 337.1 10 423 0.064 0.11 1.94 
D-5 6.81 704 484.3 30 462 0.028 0.16 6.32 
D-6 7.20 690 474.7 48 485 0.079 0.04 0.98 
D-7 7.81 750 516 20 398 0.016 0.1 0.87 
D-8 7.93 620 426.6 19 295 0.004 0.05 0.31 
D-9 7.85 670 461 21 440 0.098 0.05 0.34 
D-10 7.87 720 495.4 24 390 0.001 0.61 0.09 
D-11 7.67 840 578 22 430 0.011 0.39 0.59 
D-12 7.49 1,830 1,259 490 690 0.006 0.07 0.12 
D-13 7.81 960 660.5 55 485 0.005 0.04 0.09 
D-14 7.92 780 536.6 20 392 0.002 0.10 0.09 
D-15 7.73 770 529.8 40 410 0.013 0.05 0.30 
D-16 7.81 800 550.4 58 350 0.005 0.04 0.12 
D-17 7.83 840 578 40 425 0.009 0.05 0.30 
D-18 7.66 890 612.3 30 440 0.02 0.52 4.72 
D-19 7.82 840 578 20 435 0.027 0.04 3.64 
D-20 7.82 830 571 65 410 0.022 0.75 4.93 
D-21 8.11 580 399 20 290 0.001 0.09 0.01 
D-22 7.92 680 467.8 22 395 0.001 0.42 0.01 
D-23 7.54 1,590 1,094 335 740 0.001 0.09 0.01 
D-24 7.48 1,230 846.2 202 505 0.007 0.22 0.01 
D-25 7.85 550 378.4 30 403 0.02 0.09 0.01 
D-26 7.91 520 357.8 21 285 0.007 0.92 0.18 
D-27 7.72 700 481.6 20 401 0.024 0.49 4.05 
D-28 7.63 1,995 1,372.6 615 810 0.002 0.04 0.20 
D-29 7.91 700 481.6 50 380 0.001 0.04 0.01 
D-30 7.72 894 615.1 110 545 0.003 0.81 1.02 
D-31 7.91 660 454.1 20 360 0.022 0.04 0.01 
D-32 8.12 910 626.1 70 392 0.006 0.04 0.10 
WHO (2011a)  6.5–8.5 – – 250 500 0.01 0.3 0.5 
Environment Conservation Rules (ECR 1997)  6.5–8.5 – 1,000 600 500 0.05 1.0 0.1 

The amount of dissolved mineral salts in water determines the EC and is dependent on the concentration, mobility, and valence of the present ions. From the conductivity investigation, it is observed that the water from almost of all the TWs has some dissolved mineral content. From convention, drinking water has been categorized into: (i) good drinking water for humans (EC <800μS/cm), (ii) can be consumed by humans (EC <800–2,500μS/cm), and (iii) not recommended (EC >2,500 μS/cm). It is seen that 59.37% of TWs (19 out of 32) supply good drinking water and at the same time 40.63% of TWs (13 out of 32) supply drinking water that can be consumed by humans. These results clearly indicate that water in the study areas was considerably ionized and has a higher level of ionic concentration activity due to excessive dissolved solids (USEPA 2012). It is said that drinking water of higher conductivity is not always safe for regular drinking as it may be the cause of hypertension, kidney failure, and stone deposition in the intestines. According to the Drinking Water Inspectorate (2005), drinking water with conductivity higher than 2,500 μS/cm at 20 °C is not recommended for human consumption. The highest EC, 1,995 μS/cm, was found in sample no. D-28 and may be due to high concentration of ionic constituents present in the water bodies.

EC level can be used as an indirect measurement of TDS (Bityukova & Petersell 2010) that represent the amount of inorganic salts, such as calcium, magnesium, sodium, potassium, carbonate, chloride, sulfate, or nitrate, and organic matter present in water (WHO 2011a). According to WHO (2011a), in terms of palatability, water can be categorized according to the level of TDS value as excellent (<300 mg/L), good (300–600 mg/L), fair (600–900 mg/L), poor (900–1,200 mg/L) and unacceptable (>1,200 mg/L). From the investigation it is seen that no tube well is in the excellent category on the basis of TDS rating. There are 24 out of 32 (75%) TWs providing good quality of water. From the results it is noted that 15.62% and 3.13% of TWs are fair and poor categories, respectively. Only two TWs (6.25%) provide unacceptable water. According to BDS and the WHO standard value level of TDS in water, <1,000 mg/L is acceptable and >1,000 mg/L is unacceptable for drinking purposes. 90.62% (29 out of 32) of TWs are within the acceptable limit while 9.38% (D-12, D-23, and D-28) exceed the limit.

Chloride may present naturally in groundwater and also originate from dissimilar sources such as weathering, leaching of sedimentary rocks, percolation of seawater, etc. Chloride concentration should not surpass 250 mg/L according to the WHO. It produces a brackish taste at between 250 mg/L and 500 mg/L (Trivedy & Goel 1984), which makes it obnoxious for human consumption. It is seen from Table 2 that 29 out of 32 TWs, i.e., 90.62% of TWs, provide chloride up to 250 m/L. It means that 9.38% of the total TWs exceeded the WHO standard for chloride content. It is also observed that although the WHO standard value for chloride is ≤250 mg/L that for BDS value is ≤600 mg/L. From the results 31, i.e., 96.87% of TWs meet the BDS value and the rest, i.e., 3.13% (only one) exceeded the allowable limit, hence unsuitable for drinking. Many of salts, especially NaCl, are present in dissolved state in groundwater for tube well D-28. People consuming highly chloride contaminated water have a risk of heart and kidney diseases (WHO 1997). Chloride toxicity has been observed in those cases where it is impaired with sodium (WHO 1978). When excess chloride concentration is present with excess sodium, it may cause congestive heart failure hypertension (ISO 1989).

Hardness (TH) is composed by both temporary and permanent hardness and symbolizes the water dissolved calcium and magnesium salts due to water contact with ground rocks (APHA 2012). These salts are very acerbic and deposit scale in different types of boilers. McGowan (2000) and WHO (2011b) categorized water as soft, moderately hard, hard, and very hard when its hardness levels are 0–60 mg/L, 61–120 mg/L, 121–180 mg/L, and >180 mg/L, respectively. Hardness of water is primarily due to the presence of salts of calcium and magnesium and also increases the boiling point of the water (Murhekar 2011). In our study, no samples are soft, moderately soft, or hard on the basis of TH. All of the samples were very hard, reflecting the geological composition of the area, i.e., Kushtia is limestone ground (WHO 2011a). This parameter does not cause harmful health effects (Leurs et al. 2010; Ahmed et al. 2015); however, the recommended values in the BDS range from 200 to 500 mg/L (ECR 1997). The obtained results clearly indicate that 84.37% of water samples presented lower values than permissible limits and 15.63% of TWs exceeded the limits that are very harmful for humans.

Arsenic is widely distributed throughout Earth's crust and is usually present in the form of compounds with sulfur and many metals such as copper, cobalt, lead, and zinc. Major sources of arsenic exposure to the environment are food, water, soil, and air. The universally reported symptoms of arsenic exposure are skin lesions, developmental effects, cardiovascular disease, melanosis, keratosis, ulcer, gangrene, lung disease, kidney failure, liver failure, neurotoxicity, and arsenicosis (FAO UNICEF, WHO & WSP 2010). There are 18 TWs, 56.25% of the total, that provide almost arsenic-free (0.001–0.01 mg/L) water. These TWs are within both BDS (0.05 mg/L) and WHO (0.01 mg/L) permissible limits. In the investigation there are 11 TWs (34.37%) that provide water of As content 0.001–0.05 mg/L, higher than the WHO guideline but within the BDS limit. Three TWs were found (D-4, D-6, and D-9) where arsenic level exceeded 0.05 mg/L which is unsafe for humans. A number of mechanisms regarding the release of arsenic into the environment have been proposed by different scientists at different times. The pyrite oxidation hypothesis suggests that pyrite and arsenopyrite are deposited as pockets in aquifer sands and are oxidized and released into the groundwater. The oxidation is initiated by the entry of air into the aquifer due to lowering of the water table, which occurs because of the large abstraction of groundwater for irrigation. In this hypothesis, the oxidation of pyrite and arsenopyrite may increase the concentration of sulfate along with the arsenic in a few cases at our study area.

Iron is found as the iron Fe2+ and Fe3+ ions which combine with oxygen and sulfur containing compounds to form oxides hydroxides, carbonates, and sulfides (Elinder 1986). Large amounts of iron in drinking water can give an objectionable metallic taste. It can also promote the growth of iron bacteria and make the water distasteful (Yagoub & Ahmed 2009). There are 23 TWs containing iron, 71.87% of the total provide water below the WHO standards (<0.30 mg/L) and comply with both BDS (0.30–1.0 mg/L) and WHO permissible limits. In this investigation, there are eight TWs (25%) that provide water of iron content 0.30–1.0 mg/L, within BDS permissible limit but exceeding the WHO guideline value. This reveals that water of 31 TWs is safe from iron concentration according to BDS guideline value. There is only one TW (3.13%) that provides water with iron content higher than BDS (>1.0 mg/L) guideline value. It is seen from Table 2, that the highest value is 1.45 mg/L found in sample no. D-3, which may be produced from iron oxides that occur in groundwater with other elements, e.g., Mn, As, etc. A few scientists have suggested that the presence of iron in underground drinking water could be due to its percolation from granitic and metamorphosed rocks into groundwater, i.e., water–rock interaction. Iron is an essential element in human nutrition, required for hemoglobin to transport oxygen from the lungs to the cells or it can be a dangerous toxin. The health effects of iron in drinking water may include warding off fatigue and anemia.

Manganese is a mineral that naturally occurs in rocks and soil, usually with iron. The central nervous system is the chief target of Mn toxicity, especially causing neurological disorders in children (ATSDR 2000). Manganism originates from exposure to excessive levels of manganese and is characterized by a ‘Parkinson-like syndrome’ (Mergler et al. 1994). Concentration of Mn in water up to 0.5 mg/L is the WHO standard whereas BDS maximum permissible limit is 0.1 mg/L. When Mn concentration exceeds 0.5 mg/L in water it becomes a health risk. There are 12 TWs (37.5%) providing water that contains manganese <0.1 mg/L and complying with both BDS (0.1 mg/L) and WHO (0.5 mg/L) permissible limits. In this investigation, there are 20 TWs (62.5%) that provide water of manganese concentration higher than 0.1 mg/L, which means that the water supplied by these wells exceeds the BDS standard guideline value and is thus unsuitable for drinking purposes, but according to the WHO standard (0.5 mg/L), the water of ten TWs may be drinkable. Like iron, it is suggested that manganese is most probably produced from different ores that are soluble in groundwater. In other words, the presence of manganese in underground drinking water could be due to its percolation from granitic and metamorphosed rocks into groundwater, i.e., water–rock interaction. In fact, manganese occurs naturally in ores that may erode into groundwater sources.

Bacteriological analysis

In our investigated areas, groundwater is the principal source of drinking water and the major problem in water potability is microbiological contamination (WHO 2011a), mostly associated with fecal contamination from wastewater or landfills (Al-Khatib & Arafat 2009). The results of the bacteriological analysis are shown in Table 3 and the contamination of fecal and total coliform in our investigated drinking water sources and type of risk are shown in Table 4. From the table, it is clearly seen that 14 TWs (43.75%) provide FC-free water, hence safe for drinking purposes, whereas ten TWs (31.25%) supply TC-free water, hence also suitable for drinking. On the other hand, the remaining 18 out of 32 TWs (56.25%) contain FC and 22 out of 32 TWs (68.75%) (Table 5) contain TC organisms. This indicates that a large proportion of water sources in our studied area contain FC and TC. Thirteen TWs are at low risk type from FC and seven from TC contamination. In addition, there are five TWs at intermediate risk type from FC but 11 TWs from TC contamination. Again, it is observed that no TWs contain higher than 50 cfu/100 mL or 100 cfu/mL FC. At the same time, three TWs contain higher than 50 cfu/100 mL total coliform that could be harmful for humans especially for children as well as older people.

Table 3

Results of bacteriological analyses of the studied groundwater samples

Sample ID No. of TWs
 
Fecal coliform, cfu/100 mL Total coliform, cfu/100 mL 
D-1 23 
D-2 34 
D-3 13 
D-4 19 67 
D-5 
D-6 11 
D-7 13 45 
D-8 
D-9 
D-10 33 >100 
D-11 31 
D-12 
D-13 
D-14 
D-15 12 
D-16 
D-17 
D-18 
D-19 15 
D-20 
D-21 
D-22 12 
D-23 
D-24 
D-25 
D-26 
D-27 
D-28 11 52 
D-29 11 
D-30 13 62 
D-31 
D-32 14 
WHO (2011a)  0 cfu/100 mL 0 cfu/100 mL 
Environment Conservation Rules (ECR 1997)  0 cfu/100 mL 0 cfu/100 mL 
Sample ID No. of TWs
 
Fecal coliform, cfu/100 mL Total coliform, cfu/100 mL 
D-1 23 
D-2 34 
D-3 13 
D-4 19 67 
D-5 
D-6 11 
D-7 13 45 
D-8 
D-9 
D-10 33 >100 
D-11 31 
D-12 
D-13 
D-14 
D-15 12 
D-16 
D-17 
D-18 
D-19 15 
D-20 
D-21 
D-22 12 
D-23 
D-24 
D-25 
D-26 
D-27 
D-28 11 52 
D-29 11 
D-30 13 62 
D-31 
D-32 14 
WHO (2011a)  0 cfu/100 mL 0 cfu/100 mL 
Environment Conservation Rules (ECR 1997)  0 cfu/100 mL 0 cfu/100 mL 

cfu = colony forming unit.

Table 4

Number of TWs contaminated with FC and TC

Category cfu/100 mL No. of TWs
 
%
 
Type of risk 
Fecal coliform Total coliform Fecal coliform Total coliform 
<1 14 10 43.75 31.25 Safe 
1–10 13 40.62 21.88 Low 
11–50 11 15.63 34.37 Intermediate 
51–100 – – 9.37 High 
>100 – – 3.13 Very high 
Category cfu/100 mL No. of TWs
 
%
 
Type of risk 
Fecal coliform Total coliform Fecal coliform Total coliform 
<1 14 10 43.75 31.25 Safe 
1–10 13 40.62 21.88 Low 
11–50 11 15.63 34.37 Intermediate 
51–100 – – 9.37 High 
>100 – – 3.13 Very high 
Table 5

Comparison of water samples with its recommend standard quality

Sl no. Parameters Unit Water quality standard
 
No. of samples exceeding water quality standard
 
% of samples exceeding water quality standard
 
WHO (2006)  Environment Conservation Rules (ECR 1997)  WHO (2006)  Environment Conservation Rules (ECR 1997)  WHO (2006)  Environment Conservation Rules (ECR 1997)  
pH – 6.5–8.5 6.5–8.5 – – – – 
EC μS/cm – – – – – – 
TDS mg/L 1,000 1,000 9.38  
Chloride mg/L 250 600 9.38 3.13 
Hardness mg/L 500 500 15.63 15.63 
Arsenic mg/L 0.01 0.05 14 43.75 9.38 
Iron mg/L 0.3 0.3–1.0 28.12 3.13 
Manganese mg/L 0.5 0.1 10 20 31.25 62.5 
Fecal coliform cfu/100 mL 18 18 56.25 56.25 
10 Total coliform cfu/100 mL 22 22 68.75 68.75 
Sl no. Parameters Unit Water quality standard
 
No. of samples exceeding water quality standard
 
% of samples exceeding water quality standard
 
WHO (2006)  Environment Conservation Rules (ECR 1997)  WHO (2006)  Environment Conservation Rules (ECR 1997)  WHO (2006)  Environment Conservation Rules (ECR 1997)  
pH – 6.5–8.5 6.5–8.5 – – – – 
EC μS/cm – – – – – – 
TDS mg/L 1,000 1,000 9.38  
Chloride mg/L 250 600 9.38 3.13 
Hardness mg/L 500 500 15.63 15.63 
Arsenic mg/L 0.01 0.05 14 43.75 9.38 
Iron mg/L 0.3 0.3–1.0 28.12 3.13 
Manganese mg/L 0.5 0.1 10 20 31.25 62.5 
Fecal coliform cfu/100 mL 18 18 56.25 56.25 
10 Total coliform cfu/100 mL 22 22 68.75 68.75 

Only one TW has higher than 100 cfu/100 mL of TC, which is ruinous to health (very high risk condition). Here, it is mentioned that drinking water must be FC and/or TC free according to BDS and WHO standards. However, in our investigated area, people are drinking water in low or intermediate ranges habitually due to unavailability of fresh water, ignorance, or convenience. Interestingly, little trouble is observed. This may be because inhabitants in this area have adapted or become used to this type of water and developed immunity to that amount of bacteria. It is also seen from this study that the people who drink water which contains a high range of bacteria often suffer various diseases like dysentery, hepatitis, typhoid fever, cholera, gastroenteritis, abdominal cramping, vomiting, nausea, headaches, fatigue, and diarrhea, possibly leading to severe dehydration, malnutrition, kidney failure, and death. Most people in this area are illiterate or have no idea regarding water quality or the reason behind the diseases talked about. At the same time, they have no capacity to buy fresh/safe water or other alternatives. From our study, it is calculated that FC and TC may enter the water sources mainly because of the distance between latrines and TWs. Latrines are sometimes very close to the TWs. Moreover, a few TWs are dug close to the sewerage line or kacca drain, and contamination of FC and TC may result from this. It was also seen that all the TWs are unprotected from excreta of birds, like crows, sparrows, magpies, martins, etc.

Some TWs have good platform conditions whereas others have not. Thus, FC and TC contamination is mostly affected by location of latrines, dustbins, drains, sewerage lines, conditions of platforms, i.e., broken, unhealthy, apron constructions of the TWs (Rahman et al. 2015).

Water quality index

Relative unit weights of each water quality parameter (Wi), rating of WQI, and status of the investigated groundwater samples are shown in Tables 6 and 7, respectively. The overall suitability of drinking water was assessed using a combined measure of water quality parameters: the WQI. The physico-chemical parameters (pH, chloride, hardness, arsenic, iron, and manganese) of water samples were used to calculate the WQI value at each sample site. We applied the weighted arithmetic WQI method (Yisa & Jimoh 2010; Tyagi et al. 2014; Akter et al. 2016) to calculate WQI values. In this method, the permissible WQI value for drinking purposes is considered to be 100, the water quality being considered unsuitable for drinking if the value exceeds 100. According to Chatterji & Raziuddin (2002), in terms of suitability, water can be categorized as excellent (WQI = 0–25, grading A), good (WQI = 26–50, grading B), poor (WQI = 51–75, grading C), very poor (WQI = 76–100, grading D), and unsuitable (WQI >100, grading E), respectively.

Table 6

Water quality parameters, standard values and their relative unit weights

Parameter Min. Max Mean WHO Standard (2011a) (Si) Bangladesh Standards (ECR 1997Relative unit weight based on (WHO 2011a) (Wi = 1/Si) Reason for not establishing a guideline value (WHO 2011a
pH 6.81 8.12 7.66 8.5 8.5 0.12 – 
EC (μS/cm) 520 1,995 841.09 – – – Not of health concern at levels found in drinking-water. No health-based guideline value is proposed 
TDS (mg/L) 357.8 1,372.6 578.68 1,000 0.002 Not of health concern at levels found in drinking-water. No health-based guideline value is proposed. 600 mg/L is used for palatability 
Chloride (mg/L) 10 615 84.28 250 600 0.004 – 
Hardness (mg/L) 285 810 432.84 200 500 0.005 – 
Arsenic (mg/L) 0.001 0.098 0.017 0.01 0.05 100 – 
Iron (mg/L) 0.04 1.45 0.25 0.3 1.0 3.33 – 
Manganese (mg/L) 0.01 6.32 0.99 0.4 0.1 2.5 – 
Fecal coliform (cfu/100 mL) 33 – – 
Total coliform (cfu/100 mL) >100 14 – – 
      ∑Wi = 105.96  
Parameter Min. Max Mean WHO Standard (2011a) (Si) Bangladesh Standards (ECR 1997Relative unit weight based on (WHO 2011a) (Wi = 1/Si) Reason for not establishing a guideline value (WHO 2011a
pH 6.81 8.12 7.66 8.5 8.5 0.12 – 
EC (μS/cm) 520 1,995 841.09 – – – Not of health concern at levels found in drinking-water. No health-based guideline value is proposed 
TDS (mg/L) 357.8 1,372.6 578.68 1,000 0.002 Not of health concern at levels found in drinking-water. No health-based guideline value is proposed. 600 mg/L is used for palatability 
Chloride (mg/L) 10 615 84.28 250 600 0.004 – 
Hardness (mg/L) 285 810 432.84 200 500 0.005 – 
Arsenic (mg/L) 0.001 0.098 0.017 0.01 0.05 100 – 
Iron (mg/L) 0.04 1.45 0.25 0.3 1.0 3.33 – 
Manganese (mg/L) 0.01 6.32 0.99 0.4 0.1 2.5 – 
Fecal coliform (cfu/100 mL) 33 – – 
Total coliform (cfu/100 mL) >100 14 – – 
      ∑Wi = 105.96  
Table 7

Water quality index (WQI) and status of the investigated groundwater samples

Sample ID pH
 
Chloride
 
Hardness
 
As
 
Fe
 
Mn
 
∑WiQi WQI = ∑WiQi/∑Wi Grading of water quality 
Conc. Qi WiQi Conc. Qi WiQi Conc. Qi WiQi Conc. Qi WiQi Conc. Qi WiQi Conc. Qi WiQi 
D-1 6.91 81.29 9.75 55 22 0.09 290 145 0.72 0.003 30 3,000 0.04 13.33 44.39 0.09 22.5 56.25 3,111 29.36 
D-2 7.11 83.65 10.04 18 7.2 0.03 340 170 0.85 0.02 200 2,000 0.04 13.33 44.39 0.11 27.5 68.75 2,124 20.04 
D-3 7.13 83.88 10.07 97 38.8 0.15 355 177 0.88 0.001 10 1,000 1.45 483 1,608.4 0.11 27.5 69 2,688 25.36 
D-4 7.1 83.53 10.02 10 0.02 423 211 1.05 0.064 640 64,000 0.11 36.67 122.11 1.94 485 1,212.5 65,346 616.70 
D-5 6.81 80.12 9.61 30 12 0.05 462 231 1.15 0.028 280 28,000 0.16 53.33 177.59 6.32 158 395 28,583 269.75 
D-6 7.2 84.7 10.16 48 19.2 0.08 485 242 1.21 0.079 790 79,000 0.04 13.33 44.39 0.98 245 612.5 79,668 751.87 
D-7 7.81 91.88 11.03 20 0.03 398 199 0.99 0.016 160 16,000 0.1 33.33 110.99 0.87 217 542.5 16,666 157.28 
D-8 7.93 93.29 11.19 19 7.6 0.03 295 147 0.73 0.004 40 4,000 0.05 16.67 55.51 0.31 77.5 194 4,261 40.21 
D-9 7.85 92.35 11.08 21 8.4 0.03 440 220 1.1 0.098 980 98,000 0.05 16.67 55.51 0.34 85.5 214 98,282 927.54 
D-10 7.87 91.88 11.03 24 9.6 0.04 390 195 0.97 0.001 10 1,000 0.61 203.3 676.99 0.09 22.5 56.25 1,745 16.47 
D-11 7.67 90.23 10.83 22 8.8 0.03 430 215 1.07 0.011 110 11,000 0.39 130 432.9 0.59 147 367.5 11,812 111.48 
D-12 7.49 88.11 10.57 490 196 0.78 690 345 1.72 0.006 60 6,000 0.07 23.33 77.69 0.12 30 75 6,166 58.19 
D-13 7.81 91.88 11.03 55 22 0.09 485 242 1.21 0.005 50 5,000 0.04 13.33 44.39 0.09 22.5 56.25 5,113 48.25 
D-14 7.92 93.18 11.18 20 0.03 392 196 0.98 0.002 20 2,000 0.1 33.33 110.99 0.09 22.5 56.25 2,179 20.56 
D-15 7.73 90.94 10.91 40 16 0.06 410 205 1.02 0.013 130 13,000 0.05 16.67 55.51 0.3 75 187.5 13,255 125.09 
D-16 7.81 91.88 11.03 58 23.2 0.09 350 175 0.87 0.005 50 5,000 0.04 13.33 44.39 0.12 30 75 5,131 48.42 
D-17 7.83 92.12 11.05 40 16 0.06 425 212 1.06 0.009 90 9,000 0.05 16.67 55.51 0.3 75 187.5 9,255 87.34 
D-18 7.66 90.12 10.81 30 12 0.05 440 220 1.1 0.02 200 20,000 0.52 173.3 577.1 4.72 1,180 2,950 23,539 222.15 
D-19 7.82 92 11.04 20 0.03 435 217 1.08 0.027 270 27,000 0.04 13.33 44.39 3.64 910 2,275 29,332 276.82 
D-20 7.82 92 11.04 65 26 0.1 410 205 1.02 0.022 220 22,000 0.75 250 832.5 4.93 1,232 3,080 25,925 244.67 
D-21 8.11 95.41 11.45 20 0.03 290 145 1.22 0.001 10 1,000 0.09 30 99.9 0.01 2.5 6.25 1,119 10.56 
D-22 7.92 93.18 11.18 22 8.8 0.04 395 197 0.98 0.001 10 1,000 0.42 140 466.2 0.01 2.5 6.25 1,485 14.01 
D-23 7.54 88.71 10.64 335 134 0.54 740 370 1.85 0.001 10 1,000 0.09 30 99.9 0.01 2.5 6.25 1,119 10.56 
D-24 7.48 88 10.56 202 80.8 0.32 505 252 1.26 0.007 70 7,000 0.22 73.33 244.18 0.01 2.5 6.25 7,263 68.54 
D-25 7.85 92.35 11.08 30 12 0.05 403 201 0.02 200 20,000 0.09 30 99.9 0.01 2.5 6.25 20,118 189.86 
D-26 7.91 93.06 11.17 21 8.4 0.03 285 142 0.71 0.007 70 24,000 0.92 306.7 1,021.3 0.18 45 112.5 25,146 237.32 
D-27 7.72 90.82 10.89 20 0.03 401 201 0.024 240 24,000 0.49 163.3 543.78 4.05 1,012 2,530 27,086 255.62 
D-28 7.63 89.76 10.77 615 246 0.98 810 405 2.02 0.002 20 2,000 0.04 13.33 44.39 0.2 50 125 2,183 20.60 
D-29 7.91 93.06 11.17 50 20 0.08 380 190 0.95 0.001 10 1,000 0.04 13.33 44.39 0.01 2.5 6.25 1,063 10.03 
D-30 7.72 90.82 10.89 110 44 0.18 545 272 1.36 0.003 30 3,000 0.81 270 899.1 1.02 255 637.5 4,549 42.93 
D-31 7.91 93.06 11.17 20 0.03 360 180 0.9 0.022 220 22,000 0.04 13.33 44.39 0.01 2.5 6.25 22,063 208.22 
D-32 8.12 95.53 11.46 70 28 0.11 392 196 0.98 0.006 60 6,000 0.04 13.33 44.39 0.1 25 62.5 6,119 57.75 
Sample ID pH
 
Chloride
 
Hardness
 
As
 
Fe
 
Mn
 
∑WiQi WQI = ∑WiQi/∑Wi Grading of water quality 
Conc. Qi WiQi Conc. Qi WiQi Conc. Qi WiQi Conc. Qi WiQi Conc. Qi WiQi Conc. Qi WiQi 
D-1 6.91 81.29 9.75 55 22 0.09 290 145 0.72 0.003 30 3,000 0.04 13.33 44.39 0.09 22.5 56.25 3,111 29.36 
D-2 7.11 83.65 10.04 18 7.2 0.03 340 170 0.85 0.02 200 2,000 0.04 13.33 44.39 0.11 27.5 68.75 2,124 20.04 
D-3 7.13 83.88 10.07 97 38.8 0.15 355 177 0.88 0.001 10 1,000 1.45 483 1,608.4 0.11 27.5 69 2,688 25.36 
D-4 7.1 83.53 10.02 10 0.02 423 211 1.05 0.064 640 64,000 0.11 36.67 122.11 1.94 485 1,212.5 65,346 616.70 
D-5 6.81 80.12 9.61 30 12 0.05 462 231 1.15 0.028 280 28,000 0.16 53.33 177.59 6.32 158 395 28,583 269.75 
D-6 7.2 84.7 10.16 48 19.2 0.08 485 242 1.21 0.079 790 79,000 0.04 13.33 44.39 0.98 245 612.5 79,668 751.87 
D-7 7.81 91.88 11.03 20 0.03 398 199 0.99 0.016 160 16,000 0.1 33.33 110.99 0.87 217 542.5 16,666 157.28 
D-8 7.93 93.29 11.19 19 7.6 0.03 295 147 0.73 0.004 40 4,000 0.05 16.67 55.51 0.31 77.5 194 4,261 40.21 
D-9 7.85 92.35 11.08 21 8.4 0.03 440 220 1.1 0.098 980 98,000 0.05 16.67 55.51 0.34 85.5 214 98,282 927.54 
D-10 7.87 91.88 11.03 24 9.6 0.04 390 195 0.97 0.001 10 1,000 0.61 203.3 676.99 0.09 22.5 56.25 1,745 16.47 
D-11 7.67 90.23 10.83 22 8.8 0.03 430 215 1.07 0.011 110 11,000 0.39 130 432.9 0.59 147 367.5 11,812 111.48 
D-12 7.49 88.11 10.57 490 196 0.78 690 345 1.72 0.006 60 6,000 0.07 23.33 77.69 0.12 30 75 6,166 58.19 
D-13 7.81 91.88 11.03 55 22 0.09 485 242 1.21 0.005 50 5,000 0.04 13.33 44.39 0.09 22.5 56.25 5,113 48.25 
D-14 7.92 93.18 11.18 20 0.03 392 196 0.98 0.002 20 2,000 0.1 33.33 110.99 0.09 22.5 56.25 2,179 20.56 
D-15 7.73 90.94 10.91 40 16 0.06 410 205 1.02 0.013 130 13,000 0.05 16.67 55.51 0.3 75 187.5 13,255 125.09 
D-16 7.81 91.88 11.03 58 23.2 0.09 350 175 0.87 0.005 50 5,000 0.04 13.33 44.39 0.12 30 75 5,131 48.42 
D-17 7.83 92.12 11.05 40 16 0.06 425 212 1.06 0.009 90 9,000 0.05 16.67 55.51 0.3 75 187.5 9,255 87.34 
D-18 7.66 90.12 10.81 30 12 0.05 440 220 1.1 0.02 200 20,000 0.52 173.3 577.1 4.72 1,180 2,950 23,539 222.15 
D-19 7.82 92 11.04 20 0.03 435 217 1.08 0.027 270 27,000 0.04 13.33 44.39 3.64 910 2,275 29,332 276.82 
D-20 7.82 92 11.04 65 26 0.1 410 205 1.02 0.022 220 22,000 0.75 250 832.5 4.93 1,232 3,080 25,925 244.67 
D-21 8.11 95.41 11.45 20 0.03 290 145 1.22 0.001 10 1,000 0.09 30 99.9 0.01 2.5 6.25 1,119 10.56 
D-22 7.92 93.18 11.18 22 8.8 0.04 395 197 0.98 0.001 10 1,000 0.42 140 466.2 0.01 2.5 6.25 1,485 14.01 
D-23 7.54 88.71 10.64 335 134 0.54 740 370 1.85 0.001 10 1,000 0.09 30 99.9 0.01 2.5 6.25 1,119 10.56 
D-24 7.48 88 10.56 202 80.8 0.32 505 252 1.26 0.007 70 7,000 0.22 73.33 244.18 0.01 2.5 6.25 7,263 68.54 
D-25 7.85 92.35 11.08 30 12 0.05 403 201 0.02 200 20,000 0.09 30 99.9 0.01 2.5 6.25 20,118 189.86 
D-26 7.91 93.06 11.17 21 8.4 0.03 285 142 0.71 0.007 70 24,000 0.92 306.7 1,021.3 0.18 45 112.5 25,146 237.32 
D-27 7.72 90.82 10.89 20 0.03 401 201 0.024 240 24,000 0.49 163.3 543.78 4.05 1,012 2,530 27,086 255.62 
D-28 7.63 89.76 10.77 615 246 0.98 810 405 2.02 0.002 20 2,000 0.04 13.33 44.39 0.2 50 125 2,183 20.60 
D-29 7.91 93.06 11.17 50 20 0.08 380 190 0.95 0.001 10 1,000 0.04 13.33 44.39 0.01 2.5 6.25 1,063 10.03 
D-30 7.72 90.82 10.89 110 44 0.18 545 272 1.36 0.003 30 3,000 0.81 270 899.1 1.02 255 637.5 4,549 42.93 
D-31 7.91 93.06 11.17 20 0.03 360 180 0.9 0.022 220 22,000 0.04 13.33 44.39 0.01 2.5 6.25 22,063 208.22 
D-32 8.12 95.53 11.46 70 28 0.11 392 196 0.98 0.006 60 6,000 0.04 13.33 44.39 0.1 25 62.5 6,119 57.75 

Comparison with another study in this region

Bangladesh is divided into four major geological regions, i.e., tableland, flood plain, deltaic region including coastal belt and hill tract (Chakraborti et al. 2010). The study area, Kushtia, is situated in the deltaic region where Holocene sediment is usually present, and this region is one of the highly arsenic contaminated areas in Bangladesh. From the literature, it appears that a large scale screening for arsenic in water samples (n = 2,065) was conducted in this district and 47.6% samples had As above the WHO guideline value (10 μg/L), which is very similar to our study (43.75% samples exceeded 10 μg/L). However, the previous study (Chakraborti et al. 2010) did not consider other water quality parameter such as pH, EC, TDS, chloride, total hardness, arsenic, iron, manganese, total coliforms, and fecal coliforms which provide a complete scenario of water contaminants.

CONCLUSIONS AND RECOMMENDATIONS

From the above discussions we can conclude that the health of the people of Kushtia district in Bangladesh is vulnerable to the effects of drinking water. A large number of the households consumed water of an unsuitable quality (43.75%) according to WQI values which could result in several waterborne diseases. Hence, we need to adopt steps to control the problems. As responsible citizens of Bangladesh, we should make other residents aware of the adverse effects of arsenic, manganese, and coliform bacteria present in groundwater and motivate people in the community to share safe drinking water. The unsafe TWs must be sealed, and new TWs installed in those places where access to safe drinkable water can be ensured. Otherwise, the contaminated tube well water requires treatment for further human consumption. The Department of Public Health Engineering (DPHE) is the national lead agency and exclusively responsible for provision of safe drinking water supply, sanitation facilities, and waste management in the country. DPHE and other non-government organizations (NGOs) combined can take some steps such as installation of treatment plants for mitigating the risks in our investigated area.

REFERENCES

REFERENCES
Ahmed
F.
,
Aziz
M. A.
,
Alam
M. J.
,
Hakim
M. A.
,
Khan
M. A. S.
&
Rahman
M. A.
2015
Impact on aquatic environment for water pollution in the Vahirab River
.
Int. J. Eng. Sci
.
4
(
8
),
56
62
.
Akter
T.
,
Jhohura
F. T.
,
Akter
F.
,
Chowdhury
T. R.
,
Mistry
S. K.
,
Dey
D.
,
Barua
M. K.
,
Islam
M. A.
&
Rahman
M.
2016
Water Quality Index for measuring drinking water quality in rural Bangladesh: a cross sectional study
.
J. Health Popul. Nutr.
35
(
4
),
1
12
.
Amanatidou
E.
,
Adamidou
K.
,
Trikoilidou
E.
,
Katsiouli
F.
,
Patrikaki
O.
&
Tsikritzis
L.
2007
Physicochemical and microbiological characteristics of the potable water supply sources in the area of Kozani, Western Macedonia
.
Desalination
213
,
1
8
.
American Public Health Association (APHA)
2012
Standard Methods for the Examination of Water and Wastewater
.
American Public Health Association
,
Washington, DC
.
ATSDR
2000
Toxicological Profile for Manganese
.
United States Department of Health and Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry
,
Atlanta, GA
.
Bello
O. O.
,
Osho
A.
,
Bankole
S. A.
&
Bello
T. K.
2013
Bacteriological and physicochemical analyses of borehole and well water sources in Ijebu-Ode, Southwestern Nigeria
.
Int. J. Pharm. Biol. Sci
.
8
,
18
25
.
Bityukova
L.
&
Petersell
V.
2010
Chemical composition of bottled mineral waters in Estonia
.
J. Geochem. Explor
.
107
,
238
244
.
Chakraborti
D.
,
Rahman
M. M.
,
Das
B.
,
Murrill
M.
,
Dey
S.
,
Mukherjee
S. C.
,
Dhar
R. K.
,
Biswas
B. K.
,
Chowdhury
U. K.
,
Roy
S.
,
Sorif
S.
,
Selim
M.
,
Rahman
M.
&
Quamruzzaman
Q.
2010
Status of groundwater arsenic contamination in Bangladesh: a 14-year study report
.
Water Res
.
44
,
5789
5802
.
Chatterji
C.
&
Raziuddin
M.
2002
Determination of water quality index (WQI) of a degraded river in Asanol Industrial area, Raniganj, Burdwan, West Bengal
.
Nature, Environmental and Pollution Technology
.
1
(
2
),
181
189
.
Department of International Development (DFID)
2005
Addressing the Water Crisis: Healthier and More Productive Lives for Poor People
.
Strategies for Achieving the International Development Targets, Department of International Development
,
London
,
UK
.
Drinking Water Inspectorate
2005
Guidance on the Water Supply (Water Quality) Regulations 2000 (England) and the Water Supply (Water Quality) Regulations 2001 (Wales). Available at: http://www.legislation.gov.uk/uksi/2000/3184/contents/made; 2. https://www.legislation.gov.uk/wsi/2001/3911/contents/made and 3. Web page: http://www.dwi.gov.uk/stakeholders/guidance-and-codes-of-practice/Regs%202000%20(England)%20&%202001%20(Wales).pdf).
Elinder
C.-G.
1986
Iron
. In:
Handbook on the Toxicology of Metals
(
Friberg
L.
,
Nordberg
G. F.
&
Vouk
V. B.
, eds).
Elsevier
,
Amsterdam
, pp.
276
297
.
Environment Conservation Rules
1997
E.C.R.-Schedule-3
.
Department of Environment and Forest Ministry
,
Bangladesh
, pp.
205
.
Eze
S.
&
Madumere
I.
2012
Physicochemical and microbiological analysis of water bodies in Uturu, Abia State, Nigeria
.
Asian J. Nat. Appl. Sci
.
1
,
58
65
.
FAO, UNICEF, WHO & WSP
2010
Towards an Arsenic Safe Environment
.
22 March, 2010
.
A Joint Publication of FAO, UNICEF, WHO and WSP
.
Govindarajan
M.
&
Senthilnathan
T.
2014
Groundwater quality and its health impact analysis in an industrial area
.
Int. J. Curr. Microbiol. App. Sci
.
3
,
1028
1034
.
Harvey
P. A.
2004
Borehole sustainability in rural Africa: Analysis of routine field data
. In:
Proceedings of 30th WEDC International Conference
,
Vientiane, Lao PDR
.
Howard
K. W. F.
1997
Impacts of urban development on groundwater
. In:
Environmental Geology of Urban Areas
(
Eyles
E.
, ed.).
Special Publication of the Geological Association of Canada
,
St. John's
,
Canada
, pp.
93
104
.
International Organization for Standardization
1986
Water Quality – Detection and Enumeration of the Spores of Sulfite-Reducing Anaerobes (Clostridia). Part 2: Method by Membrane Filtration. 1986 ISO 6461-2:1986. Available at: https://www.iso.org/standard/12818.html
.
International Organization for Standardization
1989
Water Quality Determination of Chloride
.
ISO 9297:1989
,
ISO
,
Geneva
.
MacDonald
A. M.
&
Davies
J.
2002
A Brief Review of Groundwater for Rural Water Supply in Sub-Saharan Africa
.
British Geological Society
,
Nottingham
,
UK
.
McGowan
W.
2000
Water Processing: Residential, Commercial, Light Industrial
, 3rd edn. Water Quality Association, Lisle, IL.
Mergler
D.
,
Huel
G.
,
Bowler
R.
,
Iregren
A.
,
Belanger
S.
,
Baldwin
M.
,
Tardif
R.
,
Smargiassi
A.
&
Martin
L.
1994
Nervous system dysfunction among workers with long-term exposure to manganese
.
Environ. Res
.
64
,
151
180
.
Murhekar
G. K.
2011
Aqueous Environmental Geochemistry
.
Prentice Hall
,
Upper Saddle River, NJ
.
Rahman
M. A.
,
Islam
M. M.
&
Ahmed
F.
2015
Physico-chemical and bacteriological analysis of drinking tube-well water from some primary school, Magura, Bangladesh to evaluate suitability for students
.
Int. J. Appl. Sci. Eng. Res
.
4
(
5
),
735
749
.
Thivya
C.
,
Chidambaram
S.
,
Thilagavathi
R.
,
Nepolian
M.
&
Adithya
V. S.
2014
Evaluation of drinking water quality index (DWQI) and its seasonal variations in hard rock aquifers of Madurai District, Tamilnadu
.
Int. J. Adv. Geosci
.
2
,
48
52
.
Trivede
P.
,
Bajpai
A.
&
Thareja
S.
2010
Comparative study of seasonal variations in physico-chemical characteristics in drinking water quality of Kanpur, India with reference to 200 MLD filteration plant and groundwater
.
Nat. Sci.
8
,
11
17
.
Trivedy
R. K.
&
Goel
P. K.
1984
Chemical And Biological Methods for Water Pollution Studies
.
Environmental Publications
,
Karad
,
India
.
Tyagi
S.
,
Singh
P.
,
Sharma
B.
&
Singh
R.
2014
Assessment of water quality for drinking purpose in District Pauri of Uttarkhand India
.
Appl. Ecol. Environ. Sci
.
2
(
4
),
94
99
.
US Environmental Protection Agency (EPA)
2012
Water: Monitoring & Assessment_5.9 Conductivity
.
United States Environmental Protection Agency
,
Washington, DC
.
Vaishali
P.
&
Punita
P.
2013
Assessment of seasonal variations in water quality of River Mini, at Sindhrot, Vadodara
.
Int. J. Environ. Sci
.
3
,
1424
1436
.
Van Vuuren
L.
2013
Institutional conundrum sinking groundwater supply in North West Town
.
Water Wheel
.
12
,
17
19
.
Von Brömssem
M.
,
Markussen
L.
,
Bhattacharya
P.
,
Ahmed
K. M.
,
Hossain
M.
,
Sracek
O.
,
Thunvik
R.
,
Hasan
M. A.
,
Islam
M. M.
&
Rahman
M. M.
2014
Hydrogeological investigation for assessments of the sustainability of low-arsenic aquifers as a safe drinking water source in regions with high-arsenic groundwater in Matlab, southeastern Bangladesh
.
J. Hydrol
.
518
(
C
),
373
392
.
WHO Regional Office for Europe
1978
Sodium, Chlorides, and Conductivity in Drinking Water, A Report on A WHO Working Group
.
EURO Report and Studies 2
,
Copenhagen
.
World Health Organization (WHO)
1996
Guidelines for Drinking Water Quality
,
2nd ed
n.
World Health Organization
,
Geneva
.
World Health Organization (WHO)
1997
Guideline for Drinking Water Quality, Health Criteria
,
2nd ed
n, Vol.
2
.
World Health Organization
,
Geneva
.
World Health Organization (WHO)
2006
Guidelines for Drinking Water Quality First Addendum to Third Edition
,
Vol. 1, Recommendations
.
WHO Press
,
Geneva
.
World Health Organization (WHO)
2011
a
Guidelines for Drinking Water Quality
,
4th edn
.
WHO Press
,
Geneva
.
World Health Organization (WHO)
2011
b
Hardness in Drinking-water. Background document for development of WHO Guidelines for Drinking-Water Quality
.
WHO Press
,
Geneva
.
Yisa
J.
&
Jimoh
T.
2010
Analytical studies on water quality index of river Landzu
.
Am. J. Appl. Sci
.
7
,
453
458
.