There are potentially thousands of people who don’t know they’re infected and are unintentionally spreading the disease, either because they’re asymptomatic, or they’ve yet to receive their test results and are continuing life as normal.

But there is an alternative to help detect, track, and stop the spread of COVID-19: sewage testing.

Promising results

Studies show promising results when testing sewage for COVID-19 and using the insights to plan a response. Countries like the UK now include wastewater testing and management in their COVID-19 alert systems.

This comes after studies found that SARS-CoV-2, the virus that causes COVID-19, was present in sewage systems long before there was a confirmed hospital case, and long after a once-positive person tested negative.

Here are some of the most interesting findings from recent research:

  • In Massachusetts, higher-than-expected levels of SARS-CoV-2 were detected in local sewage, suggesting that far more people had been infected than were identified by individual testing.
  • In the Netherlands, researchers found that SARS-CoV-2 had entered local sewers before the city had reported any confirmed cases of COVID-19. In another study, researchers detected COVID-19 hotspots days, and sometimes weeks, before those cases appeared in hospital admissions data and clinical testing.
  • In South Africa, the Water Research Commission has launched a research programme in support of wastewater surveillance, with a view to further implementing it in SA’s water sector. If successfully implemented, such surveillance will ease the individual testing burden and enhance the fight against COVID-19.
  • SARS-CoV-2 was present in a patient’s faeces up to 33 days after the patient had tested negative for COVID-19, and remains viable in sewage for up to 14 days.

It’s important to note that, although this collectively suggests that there’s a risk of widespread distribution of COVID-19 through the sewerage system, there’s no clear consensus of faecal-oral contamination. That said, sewage testing may hold the key in effectively fighting the pandemic and tracking the virus’s prevalence down to the urban and community level.

Wastewater lets us sample a whole community at once, even with limited resources. Based on the concentration of the virus in the sewage, we can calculate the ratio of infections and viral loads in a community. Areas with higher concentrations suggest higher numbers of infected people – and therefore a more urgent need for resources. Research on this is ongoing

Early warning system

The ability to detect Coronavirus before a confirmed hospital case is crucial in non-sewered areas that have limited testing and tracing resources, poor sanitation and water infrastructure, or are not equipped to handle large patient volumes.

Think of it as an early warning system that helps authorities detect a sudden spike in infections before hospitals start filling up, allowing them to better coordinate emergency response efforts. It gives hospitals a chance to prepare for more patients while authorities implement measures to control the spread, like localised lockdowns.

This can aid with current thinking that it is better, from a socio-economic perspective, to lock down an infected city and surrounding areas – rather than the whole country. A gradual decline in SARS-CoV-2 sewage concentrations in one area might signal that lockdown is working and that authorities can implement a reopening plan.

Sewage testing is an inexpensive, evidence-based way to know where to target relief efforts and resources for maximum impact rather than spreading them too thin. Emergency response moves to a regional level, which is more manageable and effective than trying to curb the spread through a nationwide lockdown.

Unlike the current human resource-intensive approach to individual testing, where results are delayed and data is outdated by the time it’s captured, wastewater testing offers a near real-time analysis of sewage as it passes through the system, and provides visual insights into the spread of COVID-19 to identify populations most at risk.

Digital support for resilient cities

Monitoring sewage can also help authorities to detect polio, Hepatitis A, Norovirus, and other communicable diseases, as well as antibiotic-resistant strains of bacteria. What’s more, it provides a good indication of a community’s health and offers interesting insights into their lifestyle and nutrition habits.

One of our current initiatives involves the creation of a ‘Corona Dashboard’, in collaboration with KWR, which combines the disciplines and expertise of water management and digital transformation, so authorities can respond faster and more effectively to future pandemics and public health concerns. That’s because all water quality data is in one place, and levels of chemicals, antibiotics, and bacteria are visually represented to make it easy to spot an anomaly. A higher chemical concentration, for example, will affect how the wastewater is treated, to ensure only safe, compliantly treated water is returned to the environment.

The fiscus may be unable to fund new water and sanitation infrastructure for a long time, so we have to be innovative and creative with what we already have. In digitising and optimising existing assets and making better use of health data from sewerage and wastewater systems, authorities can easily do more with less – and they can help other emerging countries to do the same.

Wastewater treatment plants are not just dumping grounds for humanity’s waste. They’re symbols of renewal and sustainability. They’re carefully balanced ecosystems that can help us save and sustain lives.

We have an opportunity to Build Back Better and to create future-proof, resilient societies that are better prepared to manage the next public health crisis. In appreciating the crucial role that wastewater plays in the wellbeing of society, I hope it will also highlight the unacceptable inequalities when it comes to basic sanitation services, but that’s a conversation for another day.