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Globally, ~1 billion people, mostly residing in Africa and South Asia (e.g. India), still lack access to clean drinking water and sanitation. Resulting, unsafe disposal of fecal waste from open-defecation to nearby drinking water sources severely endanger public health. Until recently, India had a huge open-defecating population, leading declining public health from water-borne diseases like diarrhoea by ingesting polluted water, mostly sourced to groundwater. However, in recent past, sanitation development to achieve Sustainable Development Goals (SDGs) has been encouraged throughout India, but their effect to groundwater quality and human health conditions are yet-unquantified. Here, for the first time, using long term, high-spatial resolution measurements (>1.7 million) across India and analyses, we quantified that over the years, groundwater fecal coliform concentration (2002–2017, −2.56 ± 0.06%/year) and acute diarrheal cases (1990–2016, −3.05 ± 0.01%/year) have significantly reduced, potentially influenced by sanitation development (1990–2017, 2.63 ± 0.01%/year). Enhanced alleviation of groundwater quality and human health have been observed since 2014, with initiation of acceletated constructions of sanitation infrastructures through Clean India (Swachh Bharat) Mission. However, the goal of completely faecal-pollution free, clean drinking water is yet to be achieved. We also evaluated the suitability of using satellite-derived night-time light (NLan, 1992–2013, 4.26 ± 0.05%/year) as potential predictor for such economic development. We observed that in more than 80% of the study region, night-time light demonstrated to be a strong predictor for observed changes in groundwater quality, sanitation development and water-borne disease cases. While sanitation and economic development can improve public health, poor education level and improper human practices can strongly influence on water-borne diseases loads and thus health in parts of India. [ABSTRACT FROM AUTHOR]

More than quarter of underprivileged global population, who lack access to basic sanitation and clean drinking water, live in India. Consequently, every year, millions suffer with enteric diseases from drinking faecal-contaminated groundwater. The UN Sustainable Development Goal lists access to safe water and basic sanitation for all by 2030, as their sixth goal. For the first time, the role of economic improvement on decrease in water-borne faecal pathogens was studied across Indo-Ganges–Brahmaputra river basin (IGB) for almost last three decades, to delineate the long-term improvement trends of groundwater quality across India, as a consequence of development. Long-term temporal (1990–2017) and high-resolution spatial (administrative block scale, n = 2217 ) datasets of water-borne faecal pathogen concentration in groundwater and satellite-based nightlight (NL) were used to investigate the statistical trends and causal relationships. Linear and nonlinear (Hodrick–Prescott) trend analyses, panel data analyses, Bayesian vector autoregression (VAR) and lead–lag causality (LLC) analyses were performed on aforesaid culled datasets. However, the efficiency of development in alleviating the water quality and public health, and relationship with economic development, has not been well understood. Here, for the first time, using long-term, high-spatial resolution ( n = 2217 ), annual in-situ measurements and multivariate statistical models, we show that the spatially variable groundwater faecal pathogen concentration (FC, 2002–2017, - 1.39 ± 0.01 %/yr) has been significantly decreased across the basin. In most areas, increasing satellite-based NL plays a significant role (NL , 1992–2013, 3.05 ± 0.01 %/yr) in reduction of FC. However, in areas with low literacy rate surpass development. Enhanced decrease of faecal coliform concentration in groundwater possibly signifies the implementation of Clean India Mission since 2014. [ABSTRACT FROM AUTHOR]

The spatial distribution of arsenic (As) concentrations along three classified hydrogeomorphological zones in the Brahmaputra River Valley in Assam (India) have been investigated: zone I, comprising the piedmont and alluvial fans; zone II, comprising the runoff areas; and zone III, comprising the discharge zones. Groundwater (150 samples) from shallow hand-pumped and public water supply wells (2-60 m in depth) was analysed for chemical composition to examine the geochemical processes controlling As mobilization. As concentrations up to 0.134 mg/L were recorded, with concentrations below the World Health Organization and the Bureau of Indian Standards drinking-water limits of 0.01 mg/L being found mainly in the proximal recharge areas. Eh and other redox indicators (i.e., dissolved oxygen, Fe, Mn and As) indicate that, except for samples taken in the recharge zone, groundwater is reducing and exhibits a systematic decrease in redox conditions along the runoff and discharge zones. Hydrogeochemical evaluation indicated that zone I, located along the proximal recharge areas, is characterized by low As concentration, while zones II and III are areas with high and moderate concentrations, respectively. Systematic changes in As concentrations along the three zones support the view that areas of active recharge with high hydraulic gradient are potential areas hosting low-As aquifers. [ABSTRACT FROM AUTHOR]