Groundwater quality deterioration due to anthropogenic activities has become a subject of prime concern. The objective of the study was to assess the spatial and temporal variations in groundwater quality and to identify the sources in the western half of the Bengaluru city using multivariate statistical techniques. Water quality index rating was calculated for pre and post monsoon seasons to quantify overall water quality for human consumption. The post-monsoon samples show signs of poor quality in drinking purpose compared to pre-monsoon.

Urban water demand will increase by 80% by 2050, while climate change will alter the timing and distribution of water. Here we quantify the magnitude of these twin challenges to urban water security, combining a dataset of urban water sources of 482 of the world’s largest cities with estimates of future water demand, based on the Intergovernmental Panel on Climate Change (IPCC)’s Fifth Assessment scenarios, and predictions of future water availability, using the WaterGAP3 modelling framework. We project an urban surface-water deficit of 1,386–6,764 million m³.

The presence of diarrhoeagenic bacteria such as Escherichia coli in drinking water indicates faecal and sewage contamination. Testing the microbial quality of drinking water at source (n = 29) and households (n = 43) of 29 peri-urban villages of Bengaluru city, indicated that 80% and 93% of samples respectively were unfit for human consumption as per WHO standards, i.e. nil E. coli in 100 ml sample. This also indicated that water gets contaminated further at the point-of-use when compared to the source.

Under the loom of extreme climatic perturbations, human expansion and rising demand, world’s freshwater reserves are expected to suffer severe setbacks in the coming years. A major task for the international authorities in this regard is to develop a reliable inventory of existing potable water sources and identify the challenges therein. The main objective of this study was to present a spatial summary of ‘safe’ water sources in India using the most ‘authentic’, cross-sectional, open-sourced census database for 2011 ranging from household to state level.