India’s sanitation measures may be showing initial results

Using night-time light data as a proxy for economic activity, researchers report a decrease in the incidence of acute diarrhoea after 2014, when India launched a national cleanliness mission.

Alakananda Dasgupta

doi:10.1038/nindia.2020.6 Published online 14 January 2020

An old bus stop converted into a smart toilet in the Ujjain city of Madhya Pradesh, India. Under a national mission, the Indian government has built more than 6 million toilets across the country to curb open defecation.

© Swachh Bharat Mission

Faecal contamination of groundwater due to the practice of open defecation is a huge problem in India, as it often leads to acute diarrhoeal diseases (AD). Over the years, successive governments have tried to curb the practice by building toilets.

A study1 by researchers at the Indian Institute of Technology (IIT) Kharagpur, investigated whether economic development had an effect on groundwater pollution and human health as measured by the incidence of water-borne diseases. It also sought to gauge India’s preparedness for achieving Goal 6 of the United Nations’ Sustainable Development Goals, which aims to achieve clean water and sanitation for all by 2030.

Globally, about a billion people – mostly in sub-Saharan Africa and South Asia, including India – lack access to clean drinking water and sanitation. Unsafe water and improper-sanitation-borne diseases kill more children per year than malaria, measles and AIDS combined.  IIT Kharagpur Associate Professor of Hydrogeology Abhijit Mukherjee, who led the study, told Nature India that the government’s Clean India Mission launched on Mahatma Gandhi’s birth anniversary on October 2, 2014, may have reaped benefits.

Their study shows that groundwater faecal coliform concentration (FC) and cases of AD have gone down in the period between 1990 and 2017, most notably since 2014, when the mission was launched. The study quantified FC and AD in 7,010 administrative blocks across India. Based on these parameters, the researchers categorised the blocks into four areas: highly improved, improved, moderately improved and less improved.

Curbing open defecation

One of the major hurdles in curbing the practice is that even those who may have access to toilets prefer open defecation. One-third of the people in the world who defecate in the open, live in the four disadvantaged northern plain states of Uttar Pradesh, Bihar, Madhya Pradesh and Rajasthan.

In a related study2, the authors examined household preference and other factors leading to open defecation in India. They found that preference for having a toilet in the household is ranked 12 out of 21 types of consumer durables. They also found that an educated woman (with 18 years of schooling) is 3.1 times more likely to use a toilet. Households in urban areas are 19 times as likely to use a toilet as their rural counterparts.

Mukherjee told Nature India that though they did observe an overall positive impact of economic development on sanitation, groundwater pollution and health, in the moderately- and less improved areas this wasn’t the case. In these areas, people did not prefer using toilets due to low literacy level and lack of awareness. A high volume of migrant populations, who seldom have access to sanitation and clean water, was another contributory factor in these areas.

The researchers also used satellite-based night-time light (NL) data as a predictor of changes in water quality and related health conditions. Artificial light (for instance, the illumination of buildings, roads, airplane runways, railway lines or parking lots) is a defining feature of urban activity and is used as a surrogate measure of urbanisation.

The authors found that NL emissions were a significant predictor of a decrease in AD only in the highly improved area. In less-improved areas, NL was not found to be a strong predictor of AD. The authors found that improper human practice majorly determined the modest or less improvement of these areas. This had a bearing on water-borne diseases and ultimately on the Sustainable Development Goal 6.

Data concerns

Mukherjee concedes that the study had some limitations, including the nature of the secondary or tertiary data. “We had to pretty much depend on whatever was available,” he said. Although the data was enormous, due to a lack of precise geographical information, the authors had to upscale the data to an averaged block-scale observation.

His co-author Srimanti Duttagupta, a former research scholar at the School of Environmental Science and Engineering, IIT Kharagpur, says, “Since all data used for this study is from secondary sources, only continuous data has been considered.”

Another co-author Siddhartha Chattopadhyay, an assistant professor in the Department of Humanities and Social Sciences at IIT Kharagpur, concedes that better data on local practices and demography could improve their work.

Its interdisciplinary nature, integrating apparently disparate scientific socio-economic parameters, sets the study apart from others, says Auroop Ganguly, director of Sustainability and Data Sciences at Northeastern University in Boston, USA. However, the findings may not find direct use in policy making as they have not been put in the context of other disciplines or prevalent practices, and due to other limitations of data.

Kajal Lahiri, Distinguished Professor of Economics, and Health Policy, Management and Behavior, at the University of Albany in New York, USA, says the work is ‘substantive’ with a large data set from sub-divisional geographic units spread over 25 years. “The massive collaborative effort to study such an important issue in India, which lags behind even Africa in this regard, is impressive.” Lahiri says the issue of open defecation has cultural/anthropological roots. “People like to keep themselves and their houses clean, but are ambivalent regarding their neighbourhood environment.”

For the first time, NL data was used to investigate an environmental or geoscience or human health-related problem. The study demonstrates that a one-size-fits-all approach won’t work in reducing cases of AD across India.


1. Mukherjee, A. et al. Impact of sanitation and socio-economy on groundwater faecal pollution and human health towards achieving sustainable development goals across India from ground-observations and satellite-derived nightlight. Sci. Rep. 915193 (2019) doi: 10.1038/s41598-019-50875-w

2. Banerjee, A. N. et al. Demand for household sanitation in India using NFHS-3 data. Empirical Economics 53, 307–327 (2017) doi: 10.1007/s00181-017-1250-5