Shallow Tubewells Research Articles

Field Trial of an Automated Batch Chlorinator System at Two Shared Shallow Tubewells among Camps for Forcibly Displaced Myanmar Nationals (FDMN) in Cox's Bazar, Bangladesh.

Chlorination of shallow tubewell water is challenging due to various iron concentrations. A mixed-method, small-scale before-and-after field trial assessed the accuracy and consistency of an automated chlorinator, Zimba, in Rohingya camp housing, Cox’s Bazar. From August–September 2018, two shallow tubewells (iron concentration = 6.5 mg/L and 1.5 mg/L) were selected and 20 households were randomly enrolled to participate in household surveys and water testing. The field-team tested pre-and post-treated tubewell and household stored water for iron, free and total chlorine, and E. coli. A sub-set of households (n = 10) also received safe storage containers (5 L jerry cans). Overall mean iron concentrations were 5.8 mg/L in Zimba water, 1.9 mg/L in household storage containers, and 2.8 mg/L in the project-provided safe storage containers. At baseline, 0% samples at source and 60% samples stored in household vessels were contaminated with E. coli (mean log10 = 0.62 MPN/100 mL). After treatment, all water samples collected from source and project-provided safe storage containers were free from E. coli, but 41% of post-treated water stored in the household was contaminated with E. coli. E. coli concentrations were significantly lower in the project-provided safe storage containers (log10 mean difference = 0.92 MPN, 95% CI = 0.59–1.14) compared with baseline and post-treated water stored in household vessels (difference = 0.57 MPN, 95% CI = 0.32–0.83). Zimba is a potential water treatment technology for groundwater extracted through tubewells with different iron concentrations in humanitarian settings.

Impact assessment of ‘Potash for life’ project: Accelerating adoption of balanced use of fertilizers and enhancing farm income of farmers’ in Chhattisgarh, India

Rice is the major crop and the central plains of Chhattisgarh are known as Rice bowl of central India. Under present study four districts have been selected, namely Bilaspur, Durg, Raipur and Rajnandgaon. In Rajnandgaon two blocks Rajnandgaon and were selected. In Rajnandgaon block two villages Haldi and Surgee and, Arjunda village from Gonderdal block was selected to conduct survey. Two villages namely: Malud and Mahamara were selected from Nakpura and Durg blocks in district Durg. Similarly, three villages Janjra, Devri and Kopra from Fingeswer block of Raipur district was selected to conduct socioeconomic survey. In district Bilaspur Bilha block was identified in which Sendari, Kechar and Dhabipara villages were selected for the above cited purpose. From each district cooperator-farmers were selected, as in Rajnandgaon 29 farmers, in Durg 18 farmers, in Raipur 29 farmers and in Bilaspur 30 farmers. A total of 106 cooperator farmers were surveyed. 85% of area is comes under irrigated land out of total aerable portion and the major sources of irrigation are electric operated shallow tube wells and canals. The area under tube well and canal irrigated lands are 204 ha and 96 ha, respectively. It occupies about 90% (274 ha) and 92% (283 ha) area to total cropped area in kharif season and 50.6% (155.2 ha) and 49.9% (153.10 ha) area in rabi season in 2012-13 and 2014-15, respectively. Another important crop is tomato which occupies 3.3% (10.1 ha) and 3.9% (12.1 ha) in the year 2012-13 and 2014-15, respectively on sample farms. In kharif rice, use of potash increased significantly by 262.42% while the doses of nitrogen and phosphorus is reduced by 23% and 19%, respectively in assessment year over the base year. However, total nutrient use has been increased by 16% in the referred period. In rabi rice the use of potash fertilizer increased by 170.2% in the corresponding period and the doses of nitrogen and phosphoric nutrients have decreased by 30% and 24.46%, respectively. It shows that the farmers are using higher doses of potash after they have gained knowledge and education about its significances from the PFL project activity. The impact of potassic fertilizers have also been studied over crop tolerance to various stresses such as adverse weather conditions, water stress, severity of diseases and effect of natural enemies. Application of potash, protect crop from many adversaries which happened during cropping season. Many communication as well as extension techniques and tools are being used under PFL project for creating awareness regarding balanced use of fertilizers and benefits of using potash in soils. Demonstration plots are ranked first in creating awareness among cooperator farmers. Besides it, field days, publicity material, digital media, TV publicity and crop seminars were found to be most effective in communication techniques. Therefore, suitable technological interventions and policy option need to be design to encourage farmers for use of balanced inorganic fertilizers.

Management and Utilization Strategy of Water Resources for Rice Production

Declination of available water resources is threatening the dry season crop production in Bangladesh. Sustainable water management is crucial need to meet future food production. This study was aimed to determine futuristic water management strategy for rice cultivation. Both surface and groundwater is getting scarce in north-west region, whereas abundant of fresh surface water creating opportunities to irrigate dry season crops in south-central region. This study has outlined irrigation management for rice cultivation and groundwater utilization in water scarce area of north-west region. More than 75% of annual rainfall occurred during monsoon and crops other than monsoon often faced water shortage. Timely establishment of T. Aus rice on 01 May accounted average 183 mm supplemental irrigation for north-west and south-west region. Transplanting of T. Aman rice before 24 July found the low risk period of drought and gave about 1 t ha-1 yield advantage than late transplanting after 15 October. Supplemental irrigation in drought year gave up to 26% yield advantage than the rain-fed condition of T. Aman rice in experimental plot. Over exploitation of groundwater by famers for crop cultivation makes the groundwater status worsen. Farmers used 38% excess water than the actual requirement for Boro rice cultivation. For that annual groundwater withdrawal was higher than annual recharge causing groundwater level depletion in most of the districts. Groundwater table went below suction limit of shallow tubewell (STW) during dry season and thus it become unable to operate. Improved distribution system with plastic pipe, buried pipe could save about 25% of irrigation water. Alternate wetting and drying (AWD) irrigation method saved 20-25% water than farmer’s practice. Application of these on-farm water management technologies in Boro rice reduced water demand and made the groundwater balance positive as well as reduced the groundwater withdrawal pressure. On the contrary, irrigation with less saline surface water resources in river and canals of south central regions could expand Boro production and increased land productivity. Intervention of low lift pump with plastic pipe distribution in non-saline tidal areas could increase land productivity. Besides, trapped freshwater in to the canals inside the polders and re-excavation of these canals would make crop intensification. Thus, additional food production could help to achieve sustainable development goal and sustained food security. Bangladesh Rice J. 25 (1) : 37-50, 2021

Groundwater quality and its suitability for different uses in lower Djendjen Watershed, Northest Algeria

Groundwater is a vital resource in coastal areas to supply domestic, drinking, irrigation and industrial needs. To study the hydrogeochemical characteristics of groundwater and their suitability, Thirty-one (31) groundwater samples were collected from the shallow tubewells in the plain of the Djendjen river (North-East of Algeria). The water quality assessment has been carried out by evaluating the physicochemical parameters such as temperature, pH, EC, major ions i.e., Ca2+, Mg2+, Na+, K+, Cl-, SO42-, HCO3- and nutrients (NH4+, NO2-, NO3-, PO43-). The chemical parameters plotted in Piper’s diagram show the dominance of two chemical facies “calcium and sodium chloride” and “calcium bicarbonate”. Based on the analytical results, groundwater in the area is found to be generally suitable for drinking. The organic pollution index (OPI) show that the water is generally in the good quality category with no organic pollution. Chemical parameters when plotted in the U.S. Salinity diagram indicate that waters are C2S1 and C3S1 types, i.e., medium to high salinity and low sodium which is good for irrigation. Four corrosion indices were calculated (The indices include the Langelier saturation index, Ryznar stability index, Puckorius scaling index, Larson). The result indicates the corrosive nature of the majority of water samples.

INTEGRATED RAINWATER HARVESTING (RWH) AND GROUNDWATER SYSTEM FOR DOMESTIC WATER SUPPLY

The motivation of this study was minimizing usage of billing water via adopting integrated rooftop rainwater harvesting (RWH) and groundwater at Madrasah Tahfiz Darul Hikmah in Parit Kaspan, Parit Raja, Johor. Groundwater exploration using electrical resistivity method was conducted. Based on the 2-dimensional resistivity tomography result, the position of shallow tube well was pointed based on low resistivity and low chargeability. Tube well at 2-inch diameter was constructed at 20-m depth. Preliminary analysis was conducted, and a few contaminants were detected in groundwater and rainwater, making it unsafe for domestic purposes and need to be treated to an acceptable level. Multiple treatments such as sedimentation, sand and membrane filtrations, and dilution were applied to improve the groundwater quality. Few parameters were selected and analysed namely pH, turbidity, total dissolved solids (TDS) and heavy metals (i.e., Fe, Mn, Zn and Cu). Overall, the blended groundwater and rainwater water treatments efficiently reduced the concentration of pollutants in the filtered water to a compliance of recommended raw water quality standard.

Impact of geology and anthropogenic activities over the water quality with emphasis on fluoride in water scarce Lalitpur district of Bundelkhand region, India

The Bundelkhand region of India is suffering from acute water scarcity, raising concern over the potability in the region. Therefore, to develop a baseline data set of groundwater quality, sampling was carried out from the 110 existing shallow hand pumps and tube wells covering the Lalitpur district. Groundwater samples were investigated for hydro-geochemical and isotopic signatures (δ18O and δ2H) to understand the driving factors leading to water quality and its contamination in the region. The results of Hierarchical cluster analysis revealed four different clusters according to their water quality. Cluster 1 and 2 water samples have a good quality of water and these samples fall in the vicinity of major or minor drainage networks of the area. Whereas, clusters 3 and 4 are of deteriorated water quality and located far-off from the drainage networks in the study area. The findings from chemical analysis and chemometric method suggest that the groundwater composition is mainly influenced by rock weathering and anthropogenic activities. Fluoride exposure dosage for the infant and children is twice that of adults in the study area, indicating a stronger impact of fluoride concentration in infants and children. The stable isotopic analysis shows that origin of groundwater is local precipitation, with evaporative enrichment in groundwater. The groundwater of cluster 3 and 4 shows evaporative nature along with high EC and Cl concentration. The variation of concentration of ions in the study area prevails along the groundwater flow direction and surface drainage reveals the control of hydrogeological attributes in the groundwater.

Prediction of groundwater trends for irrigation in Northern Bangladesh

Abstract Groundwater trends affect the domestic, agricultural, and industrial prospects of a region. The study area is Bogura, a northern region of Bangladesh, located on the Pleistocene terrace of the Bengal Basin. The aquifer consists of medium-to-coarse sand, located at a depth of 4.66–42.68 m; groundwater is scarce during dry seasons. The water table (WT) time-series data for 2007–2019 were used for forecasting and characterizing present and future groundwater conditions using existing numerical simulations. The annual groundwater budget for discharge and storage was 2,772 and 2,442 Mm3, respectively. Thus, the annual scarcity of groundwater was 330.4 Mm3 (13.5%), excluding the surface water contribution of 10 Mm3 (0.4%). The present spacing of deep tube wells (DTWs) and shallow tube wells (STWs) was 744 and 372 m, respectively. Currently, the DTW spacing ranged 744–800 m; however, the STW spacing of 250–372 m is higher than the set distance. Hence, further installations of STWs were strictly disallowed for irrigation. WT declined by 1.0 m in the last 13 years, i.e., 0.07 m or 1.2% decline rate per annum, causing water scarcity in the region during the peak period in the dry season (June–February), thus affecting irrigation and limiting agricultural production.

Drinking Water Supply Options in Arsenic and Salinity Affected Areas of Bangladesh: A Case Study

Widespread groundwater arsenic contamination in south, south-western and north-eastern regions and high salinity in the south-western coastal region are the two major challenges for drinking water supply in Bangladesh. In this study, we assessed various water supply technologies used for mitigating arsenic and salinity in Laksam of Cumilla and Assasuni of Satkhira district. Water samples were analyzed for Arsenic, Iron, Chloride (indicator for salinity) and FC from different water extraction systems (shallow, deep and Tara tubewells), groundwater arsenic treatment units (SIDKO and READ-F), rainwater harvesting systems (RWH), pond sand filters (PSF), and managed aquifer recharge units. Most shallow tubewells, both in Laksam and Assasuni, have been found to produce arsenic contaminated water. But water from deep and Tara tubewells have been found arsenic-free, though high concentration of iron was observed in the wells in Laksam. Rainwater harvesting systems, PSF and MAR units in Assasuni have been found to provide water free from the common chemical contaminants but suffer from high bacterial contamination. Deep tubewell appear to be the most preferred option where a suitable aquifer is available. The community-scale groundwater treatment systems would require strong operation and maintenance support from the service providers to be successful.
 Environ. Sci. & Natural Resources, 12(1&2): 215-223, 2019

Production performance of Pabda (Ompok pabda) and Gulsha (Mystus cavasius) with Rohu (Labeo rohita) in natural pond conditions

The study was carried out infourselected farmer’s pond in Netrokona sadarand Barhatta upazillas(sub district) under Netrokona district during April to September 2019 having average pond area of 0.14 haeach. The ponds were prepared by removing aquatic vegetation and unwanted fish and other animals, andapplying with lime at the rate of 250 kg/ha. Five days after liming, water was supplied from shallow tubewell to the ponds and filled up to the depth of 1.5 m. The fry of Pabda (Ompok pabda) and Gulsha (Mystuscavasius) with Rohu (Labeo rohita) were stocked at the rate of 175000; 87,500 and 2000/ha, respectively.After stocking, fish were fed at a rate of 5-12% of body weight with supplementary feed (30% crudeprotein). Fish sampling were done at monthly interval to know the fish growth status and also to adjust feedration. After six months rearing, fish were harvested by repeated seine netting. Total bulk weight and numberof fish from each pond was recorded. Survival and gross production of fish of each pond were estimated. Theharvesting weight of pabda ranged from 33 to 36g. While the harvesting weight of Gulsha and Rohu rangedfrom 26-27g and 591-614g, respectively. Based on the number of fish harvested at the end of the experiment,survival ranged from 75 to 88%.Total production of Pabda (O. pabda) and Gulsha (M. cavasius) with Rohuwas estimated at 5202, 1772 and 1066 kg/ha, respectively. The total production of fish as recorded in trialponds were 8043 kg/ha

Let the Water Flow: The Impact of Electrification on Agriculture

Over one billion people worldwide live in rural areas without access to electricity. In developing countries, while governments use electrification programs to stimulate non-agricultural employment, they may also have benefits for the agricultural sector. We estimate the impacts of India's large-scale rural electrification program on agricultural output using a difference-in-difference design and a combination of administrative and satellite data. We find that electrification leads to a 1.7% increase in agricultural output which is largely driven by the rain-fed summer cropping season. Agriculture in electrified villages becomes less sensitive to rainfall shocks, which is of growing importance given worsening environmental conditions. We provide suggestive evidence that this decline in sensitivity is due to an increase in the uptake of electric shallow tube wells, particularly at the intensive margin.

Lift irrigation from dry river bed through shallow tubewell in Odisha

Lift irrigation from dry river bed through shallow tubewell in Odisha

Low cost groundwater recharge technology for poor quality groundwater areas in Agra and Bharatpur region

A low-cost groundwater recharge structure was designed and developed for Agra-Bharatpur region where groundwater is mainly saline and sodic in nature. The recharge structure comprised of silt basin, filter pit and bore hole of existing shallow tubewell. As bore well of existing tube well was used as recharge shaft, the cost of recharge structure was reduced substantially. The 9 recharge structures were installed at village Odhara in Bharatpur district during 2008–2009. The groundwater recharge helped in dilution of exiting saline groundwater during monsoon season and there was reduction in groundwater salinity upto 3 irrigations of rabi crops. Irrigations by diluted groundwater during initial stages in wheat and mustard crop improved crop yields by 10–15% during all four years of data recording. The depth to groundwater was also monitored during 2008 to 2015. There was rise in water table of the area of 2 m. It indicated improvement in groundwater availability. Thus, low-cost groundwater recharge structure is environmental friendly and cost effective technology for region where groundwater quality and groundwater availability are major issues.

Revisiting the Village Where Arsenic Contamination of Underground Water Was First Discovered in Bangladesh: Twenty-Five Years Later.

A survey was conducted in an As-affected village of Bangladesh—the first discovery of As contamination in the country—to assess the current situation and how implementation activities have worked to mitigate the problem. The As testing showed that the levels were less than the Bangladesh standard (50 µg/L) in all shallow tube-wells throughout the village. The questionnaire survey was conducted in the village as well as a neighboring As-affected village for comparison. The results revealed that there was a significant number of people using shallow tube-wells in both villages despite knowing that these wells could be contaminated with As and that safe water was available through a pipeline water supply. About 70% of responding households possessed their own water sources, mostly shallow tube-wells, and owners were less likely to choose tap water for drinking purpose than nonowners. In the village where As contamination was first reported, those individuals with a higher level of education and strong ties with neighbors were more likely to use shallow tube-well water for drinking purposes rather than tap water. This study suggests several measures to mobilize people to get safe water, namely providing subsides to install private taps, supplying public taps, and marketing and distributing handy water quality tests for households.

ASSESSMENT OF EFFECTIVENESS OF SHALLOW TUBEWELL IRRIGATION IN DHANUSHA DISTRICT, NEPAL

A survey entitled “Assessment of effectiveness of Shallow tubewell irrigation in Dhanusha district” was carried to seek the status of Shallow tubewell irrigation and its effectiveness in agriculture. A total of 30 respondents were selected on the basis of simple random sampling method who uses shallow tubewell for irrigation. Major occupation of 77% of population of survey area was agriculture and about 73% of households were doing rainfed agriculture before installation of shallow tubewell. A total of 201.23 bigha of land was irrigated and 250 families were benefited from shallow tubewell irrigation. The area under cultivation and production of crops was also found to be increased after installation of shallow tubewell. The average annual production of cereals and vegetables after use of shallow tubewell was 6.01 ton and 1.08 ton respectively. The monoculture system of cropping was changed to multiple cropping system after installing shallow tubewell. Farmers now cultivated 1-5 types of crops before which 1-2 types before shallow tubewell irrigation. Rice, wheat and vegetables were cultivated in 1258 katha, 582 katha and 32 katha of land respectively before installing shallow tubewell but after installation cultivated in 1330 katha, 697 katha and 232 katha of land respectively. Similarly, productivity of rice. increased from 95.96 to 142.08 ton, wheat from 29.98 to 46.67 ton and vegetables from 7.52 to 27.9 ton after use of shallow tubewell irrigation. Poor supply of electricity was the major problem with the index value of 0.89 followed by canal problems.

Exploring the impact of soil and water salinity on dietary behavior and health risk of coastal communities in Bangladesh

The purpose of this study was to evaluate the impact of soil and water salinity on dietary behavior and health risk in the coastal people of Bangladesh. This study was conducted among 240 respondents in rural coastal sub-districts in Khulna and Patuakhali of Bangladesh using a simple random sampling technique. To evaluate the association between health risk and salinity exposure categories, a multinomial logit regression analysis was conducted and statistical significance was declared at p ≤ 0.05. A significantly higher amount of salinity (NaCl) level was found in radish, potato, bean, bitter gourd, rice, shallow tube-well, and pond water from Patuakhali than Khulna. Males and those aged 36-50 years (RRR:1.89, SE:0.58) and 51-65 years (RRR:4.51, SE:1.81) were associated with hypertension compared with the females (RRR:0.57, SE:0.18) and age group 20-35 years. Consumption of shallow tube-well water (RRR:3.12, SE:1.46), salt content rice (RRR:1.36, SE:0.50), salt content vegetables (RRR:1.09, SE:0.09), salt content fish (RRR:2.77, SE:0.47), and intake of table salt (RRR:1.05, SE:0.03) were significantly associated with risk factors of hypertension (p < 0.01). A sustainable policy for salt reduction through dietary interventions along with the promotion of low saline foods and drinking water must be a priority with special emphasis on coastal areas.

Arsenic in drinking water sources in the Middle Gangetic Plains in Bihar: An assessment of the depth of wells to ensure safe water supply

This study assesses the depth of tubewell and the associated concentration of arsenic (As) in drinking water within the arsenic-affected regions in Bihar, India. A survey of 935 tubewell from two As-contaminated blocks in Bihar were conducted to collect and test the water samples. The results demonstrate that As concentration is mainly found in shallow tubewells (14–49 m deep), which is the main source of drinking water in the region in deep tubewells (>49 m deep), have arsenic concentration < 50 μg/L. The analytical results by field test kits (FTK) revealed that the levels of As in around 61% of the drinking water sources were above 10 μg/L, 20.8% samples contained arsenic 51-<100 μg/L, 16.9% contained 101-<300 μg/L, and 5.03% of the samples contained arsenic between 300 and 500 μg/L. Iron test results showed that around 74.4% of the samples contained iron at more than the prescribed 500 μg/L level of WHO. The study also revealed a general lack of awareness about the drinking water contamination and its associated health impacts. Therefore, awareness through various channels among the affected stakeholders will be helpful for the households to change their water sources (Saha et al., 2019).

Twenty Years of Arsenic Contamination and Arsenicosis Patients in a Village of Bangladesh

Background: Arsenic contamination in groundwater of Bangladesh was first detected in 1993 and still a major public health problem in the country. In 1997, Samta was identified as a severely arsenic contaminated village and many villagers were found to suffering from arsenicosis. Methods: A series of surveys were carried out in Samta village in the years 1997, 2002, 2008 and 2017 to assess the situation of arsenic contamination and the status of arsenicosis in the village. The water sources and the entire population of the village were included in the study. Results: In 1997 about 87% of the shallow tubewells in Samta village were arsenic-contaminated and 10.1% villagers had arsenicosis. Twenty years later in 2017, about 90% shallow tubewells were arsenic contaminated, 39 deep tubewells and a pond sand filter were installed in the village and 2.3% of the villagers had arsenicosis. On an average 43.8% arsenicosis patients had recovered from the illness and condition of 21.2% patients had deteriorated or remained unchanged. During the 20-year period 37(6.1%) arsenicosis patients and 185(1.6%) non-arsenicosis villagers had died. The main cause of death among arsenicosis patients was cancer (40.5%) and among non-arsenicosis villagers the cause was geriatric problem (11.8%). The mean age at death was 57.6 years and 61.2 years respectively. Conclusion: In twenty years, measures were undertaken to make available arsenic-safe water options and people were motivated to stop the use of arsenic-contaminated water and to increase the intake of protein and vitamin AEC rich food. Recovery had occurred in a substantial proportion of patients.

Risky responsibilities for rural drinking water institutions: The case of unregulated self-supply in Bangladesh

The drinking water sector is off track to reach Sustainable Development Goal (SDG) 6.1 with over a quarter of the world’s population lacking safe and reliable services. Policy approaches are shifting away from provision of access towards managing the multiple risks of water supply and quality. By considering how infrastructure, information, and institutional systems evolved in Bangladesh, this article identifies the unintentional consequences of reallocating management responsibility for rural water services away from government agencies towards individuals and households.Between 2012 and 2017, we estimate up to forty-five unregulated tubewells were installed privately for every publicly funded rural waterpoint. This growth rate more than doubled total national waterpoint infrastructure since 2006. The scale of growth is reflected in the declining ratio of households per tubewell from over fifty-seven in 1982 to less than two in 2017, potentially approaching market saturation. This scale of growth aligns to an observed decrease in the real price of private market shallow tubewells by seventy percent between 1982 and 2017. In 2018, we estimate households invested up to USD253 million in tubewells, nearly sixty-five percent of the total national water and sanitation sector’s household-level finance. In effect, household investments became critical to achieve the Millennium Development Goal (MDG) target of improved infrastructure access, but now pose challenges for meeting targets of safely managed services. The scale of continued private investment provides an opportunity for policymakers to explore blended public finance models to meet emerging consumer preferences, while at the same time introducing regulatory and monitoring systems.

Determination of Arsenic (As) and Iron (Fe) Concentration in Ground Water and Associated Health Risk by Arsenic Contamination in Singair Upazila, Manikganj District, Bangladesh

Contamination of drinking water by Arsenic (As) &amp; Iron (Fe) is nowadays appeared as a big concern for public health and environment as well. Immoderate and continued revelation of inorganic arsenic along with drinking water is triggering arsenicosis. High Fe and As concentration found in the study area is also appeared as very challenging to those people who are consuming the water on regular basis and they may confront to a high health risk. This study is conducted to determine the concentration of Fe and As in ground tube-well containing possible health risk in Bangladesh which examines the ground water As and Fe scenario of Singair Upazila, Manikganj district. Total 40 samples were collected from the study area. As and Fe were analyzed using Atomic Absorption Spectrophotometer (AAS). The study found As concentration ranged from 0.0011 to 0.0858 mg/L with the mean concentration as 0.04186 mg/L. Concentration of Fe was found 0.175 to 13.865 mg/L with the mean concentration as 3.600 mg/L whereas WHO standard level is 0.01 mg/L for As and 0.3 mg/l for Fe. It was also noticed that As and Fe concentration in shallow tube-well was relatively high than that in deep tube-well and a strong correlation between As and Fe was marked in the ground water. Therefore, to cope with this challenge, people should look for other sources or relocate the tube-well or treat the water for drinking and other everyday purposes.

Considering Alternate Pathways of Drinking-Water Contamination: Evidence of Risk Substitution from Arsenic Mitigation Programs in Rural Bangladesh.

Deep tubewells are a key component of arsenic mitigation programs in rural Bangladesh. Compared to widely prevalent shallow tubewells, deep tubewells reduce ground-water arsenic exposure and provide better microbial water quality at source. However, the benefits of clean drinking-water at these more distant sources may be abated by higher levels of microbial contamination at point-of-use. One such potential pathway is the use of contaminated surface water for washing drinking-water storage containers. The aim of this study is to compare the prevalence of surface water use for washing drinking-water storage containers among deep and shallow tubewell users in a cohort of 499 rural residents in Matlab, Bangladesh. We employ a multi-level logistic regression model to measure the effect of tubewell type and ownership status on the odds of washing storage containers with surface water. Results show that deep tubewell users who do not own their drinking-water tubewell, have 6.53 times the odds [95% CI: 3.56, 12.00] of using surface water for cleaning storage containers compared to shallow tubewell users, who own their drinking-water source. Even deep tubewell users who own a private well within walking distance have 2.53 [95% CI: 1.36, 4.71] times the odds of using surface water compared to their shallow tubewell counterparts. These results highlight the need for interventions to limit risk substitution, particularly the increased use of contaminated surface water when access to drinking water is reduced. Increasing ownership of and proximity to deep tubewells, although crucial, is insufficient to achieve equity in safe drinking-water access across rural Bangladesh.