Ensuring water safety amid pandemic

With over 165 000 confirmed cases worldwide, that has resulted in over 6600 deaths as on mid-March 2020, there is no doubt that the spread of the novel coronavirus COVID-19 pandemic needs to be significantly slowed or even reversed through the implementation of robust containment and control activities with immediate effect.

Coronaviruses are a large family of viruses which may cause illness in animals or humans. In humans, several coronaviruses are known to cause respiratory infections ranging from the common cold to more severe diseases such as Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS). A novel coronavirus is a new coronavirus that has not been previously identified.

Considering the newness of COVID-19, based on present-day evidence, the COVID-19 virus has not been detected in drinking-water supplies as of now. But then, this statement rests on the current knowledge of the COVID-19 virus only and does not guarantee consistency in course of time. On the other hand, the structure of the COVID-19 virus is similar to those of other surrogate human coronaviruses for which there are data about both survival in the environment and effective inactivation measures.

In fact, laboratory studies indicated that the virus could remain infectious in water contaminated with faeces for days to weeks. Therefore, it is wise to implement measures to protect against viruses in drinking water supplies and improve water safety.

The World Health Organisation (WHO), in its technical brief of March 3 2020, on 'Water, sanitation, hygiene and waste management for the COVID-19 virus' has stressed that the provision of safe water is essential to protecting human health during all infectious disease outbreaks.

World Health Organisation guidelines further recommend centralised water chlorination among others to inactivate the COVID-19 virus. In fact, other human coronaviruses have been shown to be sensitive to chlorination, so that the COVID-19 virus is likely to be more sensitive to chlorine than many other viruses.

For effective centralised disinfection, there should be a residual concentration of free chlorine of ≥0.5 mg/L after at least 30 minutes of contact time at pH < 8.0. Chlorine residual should be maintained throughout the distribution system.

By centralised water chlorination, it is implied that the chlorination needs to be done at a common water distribution point so that a time gap of at least 30 minutes exist between chlorination of water and drinking it.

Moreover, such disinfection system ensures additional water safety for purposes other than drinking as well, such as bathing, washing, cleaning, flushing, etc. However, it must be ensured that the chlorination is not done intermittently by

simply sprinkling some chlorination chemicals in the water tanks, since this might result in fluctuating residual chlorine levels with undesirable outcomes. Further, all chlorine compounds are not suitable for regular drinking water disinfection.

Finally, if your water source already maintains a continual residual concentration of free chlorine of >0.5 mg/L, then there is no need to implement further centralised chlorination in your premises. You may consult your water specialist for professional guidance in this matter.

The WHO guidance on the safe management of drinking-water applies to the COVID-19 outbreak. Extra measures are not needed. In particular, chlorination will facilitate more rapid die-off of the COVID-19 virus. Many co-benefits will be realised by safely managing water and sanitation services and applying good hygiene practices. Such efforts will prevent many other infectious diseases, which cause millions of deaths each year.

(Indraneel Das is a consultant based in Kolkata, specialising in household and municipal water quality. He can be reached at waterstandards@gmail.com)