Investigation of groundwater consumption to cope with the inadequate piped water supply in continuous and intermittent supply systems: A case study in Bangalore, India

Abstract

Although the supply of piped water to the Indian cities is increasing, the demand is not always fulfilled. This gap in water demand and supply is usually bridged by using alternate sources of water, mostly groundwater. Bangalore, the capital city of Karnataka, is one of the fastest developing metropolitan cities in India is also facing piped water supply issues. The groundwater is the main source of alternate water supply in the city. In the present study, a District Metered Area (DMA) is selected in the Bangalore South-West division; this DMA has both intermittent and continuous water supply systems. The water distribution network (WDN) of study DMA contains four inlets and three supply zones. The first is a continuous water supply system whereas the second and third are the intermittent systems. The impact of inequitable supply in the study DMA is evaluated and the consumption of groundwater to cope with insufficient water supply is analyzed. The Lorenz Curve and Gini Coefficient are used to assess the inequity in groundwater extraction under intermittent and continuous supply zones. The data from the field flowmeters, consumer meter reading, and door-to-door questionnaire survey are used for the analysis. The questionnaire survey includes RR number, presence of wells/borewells, horsepower (HP) of the pumps used, building type, the number of inhabitants, and the floors in each building. In the continuous supply system, a questionnaire survey was untaken for 80% of the connections, whereas in the intermittent supply system random sampling was used. The questionnaire survey analysis showed that 53% of the consumers in the continuous supply system rely on piped water supply, whereas others used groundwater as well as piped water supply. The study illustrated the gap in groundwater consumption between supply zones within intermittent water supply systems as well as between intermittent and continuous water supply zones. Reliability on groundwater was high even in continuous supply systems indicating insufficient pressures resulting in unsatisfied demands. The study indicated that just increasing the access to the piped water supply to the consumers is not sufficient, the acceptable quality with adequate pressure of water should be delivered to reduce the use of groundwater. The inferences from the study can be used to regulate groundwater extraction.