Microbial water quality improvement associated with transitioning from intermittent to continuous water supply in Nagpur, India

Authors: BIVINS, AARON - University Of Notre Dame; LOWRY, SARAH - Georgia Institute Of Technology; WANKHEDE, SONAL - Csir-National Environmental Engineering Research Institute; HAJARE, RAJASHREE - Csir-National Environmental Engineering Research Institute; MURPHY, HEATHER - Temple University; Borchardt, Mark; LABHASETWAR, PAWAN - Csir-National Environmental Engineering Research Institute; BROWN, JOSEPH - Georgia Institute Of Technology

Submitted to: Water Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/23/2021
Publication Date: 6/16/2021
Citation: Bivins, A., Lowry, S., Wankhede, S., Hajare, R., Murphy, H., Borchardt, M.A., Labhasetwar, P., Brown, J. 2021. Microbial water quality improvement associated with transitioning from intermittent to continuous water supply in Nagpur, India. Water Research. https://doi.org/10.1016/j.watres.2021.117301.
DOI: https://doi.org/10.1016/j.watres.2021.117301

Interpretive Summary: The country of India is in the process of improving its drinking water infrastructure so that urban households have access to water continuously. In other words, water will be available whenever a household’s tap is turned on. That is not the case now in any of India’s urban centers. The water supply to households is intermittent, sometimes on, sometimes off. The city of Nagpur, India is transitioning from an intermittent to a continuous water supply. In those water districts of Nagpur where water is supplied continuously we showed the water was less frequently contaminated with fecal microorganisms compared to districts with intermittent water supplies. In addition, there were fewer pathogens in the water from continuous-supplied districts. The infrastructure improvements to continuous-suppled water will likely reduce the number of waterborne infections.

Technical Abstract: Some 460 million people living in Indian cities are exposed to intermittent water supply (IWS), associated with degraded drinking water quality and increased risk of waterborne disease. The Nagpur municipal water supply recently upgraded its system from intermittent to continuous supply, making the transition sequentially by hydraulic zones. We used this transition to conduct cross-sectional sampling to compare microbial water quality under IWS operation and continuous water supply (CWS). In 2015 and 2017, we collected 146 grab samples and 90 large-volume dead-end ultrafiltration samples (total sampling volume of 6,925 liters). In addition to measuring traditional water quality parameters, including free and total chlorine, turbidity, heterotrophic plate count, thermotolerant coliforms, and E. coli, we also assayed DEUF concentrates by droplet digital PCR (ddPCR) for genetic targets associated with waterborne pathogens. We detected nucleic acids indicating enterotoxigenic E. coli, Shigella spp./enteroinvasive E. coli, norovirus GI and GII, adenovirus A-F, Cryptosporidium spp., and Giardia duodenalis in samples collected from household taps served by IWS. From household taps served by IWS, we observed a significant increase in the proportion of grab samples positive for culturable E. coli (IWS: 43.8%; CWS: 3.57%) and DEUF concentrates positive for gene targets associated with waterborne pathogens (IWS 61.1%; CWS: 11.1%) in samples from taps served by IWS. These findings suggest IWS is associated with increased prevalence of fecal contamination and molecular detection of waterborne pathogens, compared to CWS, and indicate IWS is less likely to meet the requirements for safely-managed drinking water as defined by the Sustainable Development Goals.