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Published on: 12/06/2020

This blog was written by Shiny Saha and Nitya Jacob.

 Indirect detection: Infected people shed the virus in their stools, and sewage samples, can indicate the viral load in the community

Indirect detection: Infected people shed the virus in their stools, and sewage samples, can indicate the viral load in the community (Photo Credit: Courage Kosi Setsoafia Saba, University for Development Studies, Ghana)

Wastewater tracking

Traces of the coronavirus have been detected in sewage. As per a guidance document (23rd April ’20) by the World Health Organization, there has been no evidence yet to suggest that the SARS–CoV-2 virus transmitted through treated or untreated wastewater is infectious. Tracking sewage for traces of the virus, however, can be one of the proxy indicators to identify where the infection is prevalent. “Routine wastewater surveillance could be used as a non-invasive early-warning tool to alert communities to new COVID-19 infections.”

In light of a high percentage of asymptomatic or undiagnosed cases, Wastewater-Based Epidemiology in the absence of adequate clinical surveillance can provide the critical information required for the management of the public health crisis. Faecal matter may in fact be a more reliable test of infection than respiratory samples. According to Dr. M.R. Seetharam, tracking sewage cannot only be useful when studying the behaviour of the virus but can also help in identifying the geographical area and the asymptomatic carriers and decode subsequent outbreaks, as has been done in the case of cholera in the past.

Participants webinar on Addressing stakeholder concerns around testing sewage for COVID-19

Participants webinar on Addressing stakeholder concerns around testing sewage for COVID-19. Photo Credit: IRC

On 22 May, the India chapter of the Sustainable Sanitation Alliance (SuSanA), WaterAid India, IRC and the India Sanitation Coalition jointly organised a webinar on Addressing stakeholder concerns around testing sewage for COVID-19. With speakers, Malini Reddy (Administrative Staff College of India), M.R. Seetharam (SVYM), Sharada Prasad (Azim Premji University), S, Vishwanath (BIOME), chaired by Sunetra Lala (SNV), the discussion was attended by 350 participants. The speakers at the webinar discussed the significance of testing sewage and the infrastructural, administrative and social implications.

Regular cleaning

The discussants shared that while most cities in India are yet to adopt wastewater tracking, it is important to be vigilant in terms of management and handling of waste. Safe management of liquid waste, faecal waste, and bio-medical waste is essential to prevent the spread of the SARS–CoV-2 virus. Therefore sewage treatment plants (STPs), community and public toilets, and faecal sludge treatment plants need to be regularly cleaned.

Further, workers at all levels should be wearing Personal Protection Equipment (PPE). A circular issued by the Central Public Health and Environmental Engineering Organisation of the Government of India, to water and wastewater utilities and pollution control boards, recommends that wastewater treatment should be followed by chlorination. Further, it suggests PPE for sanitation workers and following certain health protocols - such as testing the workers for symptoms and hygiene and disinfection of contact surfaces of the STPs.

While important, these recommendations address only the formal wastewater treatment set-up. Meeting the recommendations will require changes in the design parameters for STPs that currently do not include chlorination as a means of disinfecting sewage.

Formal and informal wastewater treatment set-ups

Sewage or wastewater testing though important has inherent challenges. Tracking sewage or wastewater is complicated, especially in the context of India, where most wastewater is a cocktail of black water, grey water, bio-medical waste and industrial effluents. Wastewater-based surveillance is focused on sewered areas. Slums and rural areas, thereby, remain untested largely because most people use onsite sanitation systems. These are not amenable to mass testing of the kind being proposed. The wastewater catchment area is huge, comprising of formal and informal set-ups. For example, in the city of Bangalore, there are 28 sewage treatment plants under the Bangalore Water Supply Sewerage Board, which cater for around 10 million people. Then there are more than 3500 decentralised STPs mandated for apartments and gated communities, and there are the community toilets run by the municipalities. This is further compounded by the fact that there are more than 500,000 onsite systems, comprising of pit toilets, community septic tanks, and temporary toilets. And, there are more than 500 honey-suckers, who collect waste from onsite systems and take it to either the STPs, or dump it in agricultural fields or stormwater drains.

It is also important to take into consideration the movement of wastewater. In most cities, wastewater flows through a vast hinterland. In the case of Bangalore, for example, treated wastewater from the formal STPs flows up to 90 kms from the city, filling up lakes and recharging aquifers in the process. Farmers then tap into this wastewater through shallow open wells for agriculture.

In terms of the informal set-up, only half of the wastewater gets collected and treated. The rest flows through stormwater drains and enters river systems. Farmers tap into the untreated wastewater – comprising of a cocktail of chemicals - for agricultural purposes. It is important to mention here that there are no standards for groundwater recharge using wastewater in India.

Guidelines and protocols

Competing priorities often tend to overshadow wastewater testing. And, in the absence of clarity on testing protocols, guidelines and regulations, Urban Local Bodies (ULBs) are hesitant to adopt sample testing. They realise if test results are positive, it can lead to scaremongering.

Handling of waste renders sanitation workers particularly susceptible. In India, the unique sanitation infrastructure implies that sanitation work comprises of a spectrum of activities – including manual scavenging, stormwater drain cleaning, collection and segregation of solid waste, construction work, and more. Informality in sanitation work is widespread which in turn increases the risk factor associated with such work. Formalising the entire spectrum of sanitation work is not feasible. And, mechanisation does not address the entire gamut of work involved. Likewise, the available PPE is not suitable for the range of activities associated with sanitation work. There are persisting issues related to practicality and comfort, which hinder, rather than aide work.

Opportunities for rethinking sanitation

The implications of sewage testing as a reliable tool to inform on the spread of the infection is significant. Regular monitoring of sewage is important in the context of COVID-19 as well as for any future public health emergency. The benefits of testing far outweigh the costs involved in the same. The willingness of ULBs, however, is an area requiring work. Additionally, it is important to have standard protocols and guidelines from the national government, and Central Pollution Control Boards in the states need to regulate STPs on the same, in order to mitigate any public health risk. Developing a risk matrix based on wastewater flows, at present, may prove useful as a starting point.

Further, in addressing the pandemic, there is also a need to shift focus from development infrastructure to social infrastructure. Ensuring health and safety of sanitation workers is crucial. Sanitation workers work and live in close proximity to other citizens. Thereby, having the right mechanisms in place is crucial from the public health outbreak point of view as well. Thus, COVID-19 presents an opportune moment to rethink sanitation and think about systemic changes towards building a sustainable public health infrastructure in India.

Watch a video recording of the webinar below. 

Under Resources you will find a synthesis document of an online discussion held in conjunction with the webinar on "Testing sewage for early warnings about COVID-19".


At IRC we have strong opinions and we value honest and frank discussion, so you won't be surprised to hear that not all the opinions on this site represent our official policy.

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