It is important to assure consumers/ citizen that the water on tap supplied by the respective water utility remains and shall continue to remain of the same quality as it was before the COVID-19 pandemic.
By Col. Bhaskar Tatwawadi (Retd)
The ongoing COVID-19 pandemic has given rise to widespread concerns about the quality of water supplied by the water utilities. These concerns stem from the reports of the presence of the viral particles reported in sewage sampled and tested from the cities having a large number of viral infections. In fact, the presence of the viral material is now likely to be used as an indicator of the outbreak of large- scale infections of the Coronavirus.
The water utilities source the raw water from rivers, lakes, and reservoirs as well as tube-wells and open wells. This raw water is tested for any impurities and pollutants. It is then treated in water treatment plants to remove all the Physico-chemical and bacteriological impurities and render it safe for human consumption. The treated water is disinfected to ensure the final elimination of disease-causing pathogens and viruses. There are prescribed standards by the WHO as well as the local regulatory bodies for the supplied water. Conformity to these standards is mandatory. The quality of water supplied on tap is regularly tested and checked.
COVID-19 and Wastewater
Water once used becomes wastewater. Wastewater is handled through a network called sewerage network. Wastewater carries the entire pollution load of communities through the sewerage network to the sewage treatment plants. Here, sewage is treated using several known and established treatment processes. Treated wastewater is then disinfected. After disinfection, it is discharged into water bodies or the environment and may find its way into the drinking water sources downstream. All the river systems supply water to a large number of cities and villages and also carry the wastewater of the upstream communities. The rivers and streams have natural purification capability based on their geographical setting and many other factors.
The Coronavirus (COVID-19) pandemic which started with a large number of infections in China and later spread all over the world reached Italy probably from December 19 to January 2020. Several other countries saw a very rapid spread of the infections. In the Netherlands, sewage samples were collected and tested in laboratories. The samples exhibited the presence of viral RNA. More sampling followed and a correlation between the concentration of the viral RNA and the probable number of infections was sought to be established. The KWR Water Research laboratory of the Netherlands led the way in this effort in Europe.
Similar sewage sampling and testing were also underway in the USA, Australia, and other European countries. The results were also similar to the Dutch findings. In India, sampling and testing of sewage samples have yielded similar findings according to a report published by the IIT Gandhinagar.
The KWR Water Research Laboratory has in its findings mentioned very clearly that the raw sewage samples when tested revealed the presence of the viral RNA. The viable presence of the COVID-19 virus was not detected. Pictures of the morphology of the virus show an outer protein cover overlaying the inner layer covering the RNA. A picture of the same is reproduced below.
It is to be noted that the RNA detected in the tested samples meant that the virus was not present in the wastewater in a viable form. The mere presence of the viral RNA shown above is not capable of causing infections through the wastewater.
The wastewater treatment follows a series of processes designed to remove most of the pollutant load including reduction/ elimination of pathogens, associated and indicative bacterial load like Coliforms and other viruses. The microbial load removal is indicated as “log removal”. The final treatment process is of disinfection using potent disinfectants like Chlorine gas, Ozone gas, and/ or Ultraviolet rays. While Chlorine gas is capable of killing almost all the pathogens, the Ozone gas and UV rays are capable of their total elimination as well as rendering the water free from viruses.
In the recent past, we have designed wastewater treatment and recycle plants using dual membrane technology with Ultrafiltration Membrane Bio-Reactor (MBR) followed by Reverse Osmosis (RO). This process regime removes all the pathogens and viruses and gives pure product water. Similar processes are used by the PUB of Singapore to produce potable water from treated wastewater. The final process after RO is disinfection using UV radiation before the storage of product water for potable reuse.
In this context, it may be noted that after the sewage is treated at the STP, the viral remains (in the form of detectable RNA) are likely to be found in the sewage sludge generated during its treatment. Sludge handling and disposal are not relevant to this article.
Quality of Water on Tap
The major concern of all consumers and citizens during the pandemic and hereafter shall be the quality of water available on tap within their homes.
In this respect, it is very important to assure each and every consumer/ citizen that the water on tap supplied by the respective water utility remains and shall continue to remain of the same quality as it was before the COVID-19 pandemic.
This is primarily because the mere presence of the COVID-19 viral RNA in the wastewater even in high concentration; anywhere in the world is not capable of causing infections. Even if raw sewage enters the drinking water source, the treatment of this polluted water at the WTP will ensure the removal of all traces of the pathogens and viruses. When the water on tap is clear without suspended impurities, it will not have infectious components of microbes and viruses because these are insoluble in water. Their presence is possible only by attachment to the suspended impurities.
The use of household water purifiers in homes is quite common in India. These purifiers also provide filtration, UV radiation, and even RO treatment to the “Water on Tap” provided by the water utilities/ municipal bodies. This also provides a final barrier to any remote likelihood of the COVID-19 virus.
To make a long story short…have no worries. Your water on tap is absolutely safe for use.
About the Author
Col. Bhaskar Tatwawadi (Retd) is the Technical Director at Tandon Urban Solutions Pvt. Ltd., Mumbai. An army veteran and a Civil Engineer from VNIT Nagpur with a Master’s degree in Environmental Engineering (with Honors) from IIT Roorkee, he has over 45 years of professional experience.
His 22 years stint in the Army, Corps of Engineers, included the construction of water treatment plants and the design of several sewerage and sewage treatment projects for military, naval, and air stations.
Later, he has worked on many projects in water and wastewater management including design and execution of rural and urban water supply and sanitation schemes, the Visakhapatnam Industrial Water Supply Project (1998), construction of the BWSSB Water Treatment Plant of 300 MLD (2000 -01) and the ﬁrst Chennai Metro-water Seawater Reverse Osmosis Plant of 100 MLD (2007). He has led design teams for several industrial wastewaters to recycle projects for automobiles and textiles industries.
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