Deep Tube Wells Research Articles

Drinking water quality assessment based on index values incorporating WHO guidelines and Bangladesh standards

Drinking water quality is one of the most severe concerns around the globe. This study aimed to assess drinking water quality for a densely populated region, the Jashore University of Science and Technology (JUST), and the surrounding villages. Fifty samples, including some filtered and boiled groundwater samples, were collected. The widely used arithmetic algorithm, the water quality index (WQI), was used to categorize the groundwater quality as per World Health Organization (WHO) guidelines and Bangladesh (BD) standards. Here, the WQI for all samples was calculated based on the concentrations of seventeen parameters (pH, TDS, TH, Ca2+, Na+, Mg2+, Cl−, SO42−, HNO3−, K, PO43−, EC, As, Zn, Mn, Cr, and Fe). The result showed that the water quality varies laterally as well as on the sampling conditions. The calculated WQI values ranged from 16.66 to 253.50 and the average value was 91.9 for the BD standards, whereas the WHO guidelines showed WQI values between 16.74 and 605.0 with an average value of 146.90. Based on the WQI values, water samples were divided into excellent, good, poor, very poor, and unfit categories which varied from BD standards to WHO guidelines for drinking purposes. 14%, 54%, 26%, and 6% of samples fell into excellent, good, poor, and inferior categories respectively as BD standards, while these values were 38%, 22%, 14%, and 14% as WHO guidelines. The result showed that deep tube-wells (>170 ft) and shallow tube-wells (<170 ft) provide mostly good and bad quality drinking water, respectively.

Multivariate statistics and hydrogeochemistry of deep groundwater at southwestern part of Bangladesh

Multivariate statistics and GIS alone with geochemical modeling were applied to investigate the hydro-geochemical characteristics of groundwater and their spatial distribution in the deep aquifer system of Bagherpara Upazila, Bangladesh. This Upazila consists of an area of 308.3 km2 and local people mostly rely on groundwater to meet the drinking water requirements. Water samples from one hundred randomly selected deep tube wells (152–198 m) were collected and analyzed for 14 water quality parameters to characterize the hydro-geochemical properties. The groundwater shows slight alkaline in nature throughout the study area. Most of the water samples were turbid and 68% of them failed to meet the drinking water quality standard prescribed by the World Health Organization (WHO). TDS concentration ranges between 280 mg/L and 1040 mg/L, with a mean value of 446.20 (±122.19) mg/L. The general order of cation and anion along the study area were Ca2+>Mg2+>Na+>K+ and HCO3->Cl−>PO43->SO42->NO3- respectively. Carbonate weathering is the dominant process for releasing ions in groundwater. Besides, the ion exchange process is active in the study area, which leads to the reduction of Na+ ions. Gibb's plot suggests a rock dominance inheritance controls the dissolution and precipitation of minerals along with the ion-exchange process, and ultimately dictates the groundwater chemistry. Besides, the Piper diagram showed that Ca2+-Mg2+-SO42- is the dominant water type in 65% of the samples followed by Ca2+-Mg2+–HCO3- water type (35%). The abundance of Ca2+ and Mg2+ ions and the alkaline nature of groundwater indicate mixed geochemical facies and reverse exchange reactions. The principal component analysis (PCA) reveals that weathering and leaching of host rocks was the main natural source, while municipal solid waste dumping, sewage discharge, and fertilizer application could be other anthropogenic factors that affect the groundwater geochemistry. In fine, the chemical characteristics of groundwater were acquired through rock dissolution, percolation, and reverse exchange process.

Factors Influencing Farmers’ Access to Formal Credit Market in Naogaon District of Bangladesh: An Empirical Analysis

Modern agriculture is expensive as performing agricultural activities nowadays requires huge investment. But some farmers do not have sufficient money to purchase and use such modern inputs like power tiller, harvester, deep-tube wells, fertilizers and pesticides in many cases. In Bangladesh, farmers are always found to face difficulties in access to credit services from both formal and informal service providers. As a result, their productivity and growth are impeded by a lack of access to agricultural loans. To investigate this phenomenon, this study aims to analyze the scenario of formal credit sources and to identify the factors that influence the access for farmers to formal credit market in Naogaon district. Primary data used for the study were collected with the aid of well-structured questionnaire from farmers and bank officials. Multi-stage sampling techniques were used to select the 200 respondents. The data were analyzed using descriptive statistics and a binary logistic regression model. The Likert scale was used to identify constraints regarding to credit acquisition from formal credit market. The results of the descriptive analysis showed that 6% farmers failed to repay their loan while 94% timely repay their loan. In terms of purpose of using agricultural credit, it is evident that 68% farmers use agricultural credit for managing their agricultural expenses while 17% respondents use loan for the purpose of paid their previous loan. In addition, 10% respondents use loans for the purpose of maintain their family expenses. Results found from the binary logit model indicate that farm size, education, farming experience, access to extension service, access to guarantor, own savings account are positively related with the log of odd ratio in favor of access to formal credit market while the same is influenced negatively by age, off-farm income and default on loan repayment. The farmers in the study area have recognized collateral security as the major constraint relating access to formal credit market followed by the lack of guarantor and bureaucratic complexity. It was recommended that the socioeconomic characteristics of farmers should be considered when formulating and implementing policies to improve farmers’ access to agricultural loans.

Assessment of Ground Water Quality for Drinking Purpose of Jalalabad Cantonment Area in Sylhet City, Bangladesh

Groundwater quality of Jalalabad cantonment area in Sylhet city is deteriorating. The study was conducted for assessing the ground water quality in drinking purpose of Jalalabad cantonment area in Sylhet city. For human survival, water is a vital resource. Total twenty-five water samples were collected from different parts of Jalalabad Cantonment area from deep aquifer-based tube wells. The collected water samples were analyzed for different physicochemical properties like Color, taste, odor, pH, electrical conductivity (EC), total dissolved solids (TDS), calcium, magnesium, sodium, potassium, boron, sulphur, copper, iron, manganese, and zinc concentrations. All the analyzed parameters compared with the standards prescribed by World Health Organization (WHO) and Bureau of Bangladesh Standard (BBS), in order to assess the ground water quality for drinking purpose. For different parameters of drinking water, the correlation matrix was also calculated. Almost all the physicochemical parameters were found within the prescribed permissible limit. Findings show that some of the parameters Cu and Zn were negatively associated with TDS, Ca2+, Mg2+, S contents.

Site suitability analysis for the construction of water reservoirs in drought‐prone areas of Bangladesh using geospatial techniques

AbstractDrought is becoming a common phenomenon in the northwestern (NW) region of Bangladesh. To address this problem, the government has taken multiple initiatives such as the construction of deep tube wells, re‐activation of abandoned deep tube wells, re‐excavation of canals, construction of cross dams, and digging wells to hold water during monsoon. However, the construction of medium‐ to large‐sized water reservoirs is somewhat overlooked or missed, which can hold large quantities of surface water and, at the same time, can recharge groundwater. Finding suitable sites for water reservoirs is a challenge. The present study aims to fulfill these gaps. We have applied a spatial multi‐criteria technique called the analytical hierarchy process (AHP) to identify suitable sites for water reservoir construction in the drought‐prone NW region of Bangladesh. A total of 12 criteria such as settlement, land use, slope, soil, groundwater depth, road network, river network, vegetation cover, rainfall, geology, protected areas, and aquifer depth were selected. The study shows that 17 percent of the area is highly suitable for reservoir construction, followed by 24 percent moderately suitable and 25 percent marginally suitable. In contrast, approximately 30 percent of the area is unsuitable for reservoir construction. Among 16 districts of northwest region, areas of Rangpur district are mostly suitable (30 percent), followed by Gaibandha district (16 percent). Construction of water reservoir in the identified areas will lower irrigation water pumping costs and will raise groundwater levels in land adjacent to the reservoir in dry season.

Identifying the Major Hydrogeochemical Factors Governing Groundwater Chemistry in the Coastal Aquifers of Southwest Bangladesh Using Statistical Analysis

People in the southwestern (SW) coastal part of Bangladesh are suffering from a severe freshwater crisis due to saline groundwater at a shallow depth. Fresh groundwater below a 200 m depth is an option, but it is costly to construct deep tubewells for the local inhabitants. The processes of salinization and freshening were previously identified using conventional methods. In this study, we brought new insight into these processes by analyzing existing datasets using multivariate statistics to identify the factors affecting groundwater chemistry. Cluster analysis (CA) revealed three major clusters. Cluster A corresponded to saline (NaCl-type) water. Cluster B was also saline (NaCl-type) water but showed mixing effects. Cluster C was fresh groundwater (NaHCO3-type) and isolated. The hydrochemical characteristics of clusters A, B and C compared remarkably well with the groundwaters from the upper shallow aquifer (USA), lower shallow aquifer (LSA) and deep aquifer (DA), respectively. Factor analysis (FA) showed that 75% of the total variance was influenced by evaporate dissolution, carbonate dissolution/precipitation, cation exchange and anthropogenic pollution to some extent. Therefore, the integrated approach showed the validity of applying multivariate statistical techniques to infer the dominant hydrochemistry and to characterize and understand a complicated hydrogeological system.

Techno-economic feasibility of solar water pumping system in North-Gujarat region, India

North Gujarat region of India is predominantly known for agro based economy. As surface water sources are very much limited in these regions, irrigation mainly depends upon underground water strata available at different water table. (Viswanathan, 2014). Close to 80 per cent of the total irrigated area is dominated by deep and shallow tube wells while canal water covers hardly 20 per cent. Gujarat ranked fourth in terms of energization of pump sets over the past three decades, showing more than fivefold increase in the number of pump sets from 2.62 Lakhs during 1983 to 14.28 Lakhs during 2017 and around 3.5 lakh applications are still pending. The agriculture sector in Gujarat utilizes about 27 per cent of the total electricity supplied by Gujarat Urja Vikas Nigam Limited. Contrarily, out of the net revenue generated by GUVNL, only 3 per cent is contributed by the agriculture consumers owing to highly subsidized rate of 60 paisa/kWh. Solar photovoltaic (PV) pumps are powered by an array of solar panels. Solar PV pumps are designed to operate on DC power produced by solar panels, or on existing AC pump with inverter. Solar pumps are easy to install and are generally “good” for the sustainability of boreholes due to their low extraction volumes spread over eight to ten hours a day. To cope up the ever increasing demand, the Gujarat government has provided solar-powered water pumps to farmers to reduce the burden on existing power plants and encourage the farmers to opt for solar powered pumps for their regular irrigation needs. A study on techno economic feasibility of solar water pumping system at farmers fields was carried out during 2015 and 2016 in the North Gujarat region. The study recommended the farmers to adopt 5 hp solar photovoltaic water pumping system coupled with micro irrigation system to promote eco-friendly daytime irrigation. The North Gujarat region is endowed by abundant solar radiation for 300–315 days with insolation of 4.5–6.5 kWh/m2/day. The system is found quite appropriate in the total head range of 5–85 m. Life cycle cost (LCC) of PV system was found to be 58.5 per cent less compared with diesel pump set, average payback period was found to be about 04 years.

TRENDS OF CLIMATIC PARAMETERS AND RESILIENCE PRACTICES OF CLIMATE DISPLACED PEOPLE OF SOUTHERN COAST OF BANGLADESH

Climate change is an extremely crucial issue in Bangladesh and is affecting people displacement in Bangladesh both sudden and gradual environmental change. To conduct the study, both the qualitative and quantitative approaches was adopted, the primary data are collected through participant observation, key informant interview (KII), Focus group discussion and Questionnaire methods. In total, 120 questionnaires were operated in 3 unions. In addition, estimate of Displacement hazard impact analysis, weight analysis, and effective adaptation analysis with various Ranking. The study prescribed 14 adaptation policies for resolving climate displacement problem, in which Incorporate climate Change in long term planning, Grass plantation, Multi crops cultivation in a land Promote awareness, Embankment construction, Salt production Using deep tube-well for pure drinking water, Livelihood skill development are highly effective adaptation policies. This study will help for resolving the displacement problem and overall adaptation goals.

Water and Sanitation Facilities in selected schools in Ibadan, South-western Nigeria

Access to clean water and sanitation is a major requirement for all countries in achieving the Sustainable Development Goals (SDG). The main aim of the study was to investigate the state and condition of water and sanitary facilities in selected secondary schools within Oyo State, Ibadan, Nigeria. Data was collected through the use of structured questionnaires and interviews with the students and teachers. Physical observation was also done onsite to supplement data gathering. The results revealed that deep-tube wells and pit latrines were the most widely used water and sanitation facilities in the study area. 70% of the schools surveyed used traditional pit latrines while 73% of schools had deep-tube wells respectively. In addition, there were limited drinking water and hand washing facilities in all the schools investigated. This study therefore recommends that government should increase funding for the provision of water and sanitation facilities in all schools in this state; as these would ensure good and enabling environment for learning as well as reducing outbreak of infectious diseases.Keywords facilities, sanitation, schools, SDG, water.

Optimizing Rural Drinking Water Supply Infrastructure to Account for Spatial Variations in Groundwater Quality and Household Welfare in Coastal Bangladesh

AbstractAchieving water security requires reconciling multiple objectives while prioritizing scarce resources for the provision of safe drinking water supplies. We examine decision‐making to invest in drinking water infrastructure in coastal Bangladesh where increasing saline intrusion in aquifers intersects with high levels of poverty for the 20 million people living in the coastal region. Multi‐objective optimization is used to explore the trade‐offs between two public policy goals: (a) maximizing overall access to improved water supplies (the greater good) and (b) maximizing access for the population with the lowest welfare (the greater need). To elucidate this trade‐off, we make use of groundwater salinity measurements, an extensive household survey and an audit of drinking water infrastructure in 1 out of Bangladesh’s 139 polders, which is home to nearly 60,000 people. We quantify the costs of a variety of drinking water supply options including deep tube wells, desalination plants, and piped systems. The recommended solutions are sequences of investments in water supply assets that are optimized to specified locations within the polder. The method is potentially scalable and transferrable to inform investments to achieve the Sustainable Development Goal (Target 6.1) of universal access to safe and affordable drinking water.

Impact of River Pollution on Human Health: A Case Study of Shitalakhya River, Dhaka, Bangladesh

Fresh water is an essential amenity to survive. However, every year many people are directly or indirectly either dying or suffering from water-borne diseases. The main purpose of this study is to make a clear view of the pollution which is happening in Char Chanpara and how frequently the residents of that area are getting affected due to excessive pollution. Shitalakhya River and its surrounding area are suffering due to water pollution every year and now the situation is becoming worse. The polluted water from the river is infecting men, women and children in every possible way. Water is the most essential requirement to perform household chores, which are done by women and hence they are more prone to diseases caused by polluted water. Because of the poor economic status, they have no other option rather than using this water for their day to day activities. Proper initiatives by the government, awareness among people, disseminating news of this polluted river, constructing deep tube wells and availability of alternative uses of water are measured by which people can be saved from problems being caused by polluted water. This study aims to identify the causes of water pollution and how the residents of the area are affected by various types of water-borne diseases through their daily usages.

Safe Drinking Water Crisis, Technological Alternatives and Constraints in Bangladesh

Groundwater resources are the primary source of meeting the water demand in Bangladesh. In rural areas, hand-pumped tube wells have been the primary source of drinking water. Though studies claim that Bangladesh has the potential to achieve universal safe drinking water supply coverage, the presence of excessive arsenic in the shallow groundwater sources, and the encroachment of salinity in the coastal aquifers in coastal regions (Satkhira, Khulna, Bagerhat, Patuakhali, Jhalakathi, Pirojpur, Barisal, Barguna etc.) hind the path. The concerned authorities of government and other non-government organizations assist the coastal people with alternative technologies like Desalination Plant, Arsenic-Iron Removal Plant, Pond Sand Filtration (PSF), Managed Aquifer Recharge, Rainwater Harvesting System, Installation of Shallow, and Deep Tube Wells. But based on case studies and surveys, this article shows how these existing technologies fail to ensure water safety within the coastal areas. The Singaporean water management policy is an example, this article advocates for necessary government intervention to ensure safe drinking water in coastal areas.

Do Community Water Sources Provide Safe Drinking Water? Evidence from a Randomized Experiment in Rural Bangladesh

AbstractHealth, and in turn income and welfare, depend on access to safe drinking water. Although the majority of rural households worldwide obtain drinking water from community water sources, there is limited evidence about how effectively these sources provide safe drinking water. This study combines a randomized experiment with water quality testing to evaluate the impact of a program that provides community deep tubewells in rural Bangladesh. The program reduces exposure to arsenic, a major natural pollutant, but not fecal contamination. Households may use fewer sources with fecal contamination, but any such effects are offset by recontamination through transport and possibly storage. The results suggest that while community deep-tubewell construction programs may reduce exposure to arsenic in Bangladesh, reducing exposure to fecal contamination may require interventions that go beyond community sources.

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.&#x0D; Environ. Sci. &amp; Natural Resources, 12(1&amp;2): 215-223, 2019

Springs of Pasighat, a valuable resource for the community: A hydrogeological study carried out using geoelectrical resistivity technique

Many springs occur in and around Pasighat. Eight major springs of the area were considered for the study. These springs are Dimple type, Fault dam type, and a combination of Fault dam and Border type. The highest discharge is 263.23 L/sec and the lowest is 1.91 L/sec. The aquifers are terrace deposits that comprise of unsorted boulders, cobbles and pebbles in sandy matrix and the springs occur at the base of different terrace levels. Due to the scarcity of dug wells or deep tube wells, subsurface investigations were done using vertical electric sounding (VES). VES data generated at six locations show H-type situation. The aquifers are at shallow depth, unconfined, and have good hydrogeological prospects. At the T2 terrace, volume of water stored is 42,14,512.5 m3 and the combined discharge of springs is 38,257.92 m3/day. These springs are recharged by precipitation and influent streams. Springs of the study area are aligned along the Himalayan Frontal Thrust (HFT) and its splays, and they have a major role in the evolution of these springs. The springs were formed due to topographic breaks and less permeable collapsed debris. Local people use spring water for the household, irrigation, laundry, and fisheries.

Physico-chemical and bacteriological evaluation of hand-dug wells in major markets in south-western Nigeria

Background: Quality of drinking water has always been a major health concern. Lack of access to safely managed water is responsible for high burden of waterborne diseases which disproportionately impact children and equity of women in Nigeria. This study, therefore, assessed the physico-chemical and bacteriological qualities of hand-dug wells in some major markets in Ibadan Southwestern, Nigeria. Methods: Twenty-two (22) water samples from hand-dug wells, measured sequentially along seven major marketswere tested for their physico-chemical and bacteriological characteristics. Following standard sampling procedures, in-situ measurements were taken for total dissolved solute (TDS), pH, electrical conductivity (EC), salinity and temperature. The most probable number – multiple tube technique was used for coliform enumeration in addition to total viable bacteria count (TVBC). Results: Mean pH (7.37±0.47), TDS (597.51±109.06mg/L), EC (748.79±110.67µS/cm), salinity (0.05±0.01mg/L), and temperature (28.75±0.58ºC) for all the marketswere withinWHO permissible limits except pH. High pH may be due to high organic matter content of the water samples. Bacteria genera comprising Esherichiacoli (37.5%), Staphylococcus aureus (25%), Proteus vulgaris (14.6%), Baccilusspp. (12.5%), Pseudomonas aeruginosa (8.3%) and Klebsiella spp. (2.1%).The mean TVBC of 500 to 192,000cfu/ml were higher than the stipulated WHO standard of &lt;1cfu/100ml.The presence of Esherichiacoli in hand-dug well water samples revealed human or animal faecal contamination.Conclusions: Water from these sources, intended for human consumption or washing of food items, maycompromise food safety and pose severe health risks to consumers. The provision of deep tube wells for safe drinking water, periodically testing of the water quality, and education of the users on improved hygiene practices will help in the provision of safe water to the public consumers.Keywords: Water quality, Hand-dug well, Bacteriological analysis, Coliforms,

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.

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.