Experts Say Unlikely That COVID-19 is Transmitted Between HDB Blocks via Wastewater System

After some residents of two HDB blocks in Hougang tested positive for COVID-19 and wastewater in nearby blocks was found to have the virus as well, residents all across the country asked the same question: can poop spread the coronavirus?

Fortunately, unless your poop has developed sentience and is roaming the streets, and as long as its confined to your wastewater system, the answer is no.

Experts Say Unlikely That COVID-19 is Transmitted Between HDB Blocks via Wastewater System

It’s unlikely that the coronavirus is being transmitted between HDB blocks through the wastewater system, infectious disease experts said.

Recently, COVID-19 viral fragments were found in wastewater samples collected from Blocks 501 and 507 Hougang Avenue 8, prompting the authorities to test residents in the block.

Earlier, a few residents living in Block 745 Yishun Street 22 also tested positive for COVID-19.

But this doesn’t mean that the coronavirus is spreading through our wastewater system.

Professor Paul Tambyah, president of the Asia Pacific Society of Clinical Microbiology and Infection (APCCMI), said that while viral fragments were found in wastewater, it doesn’t mean that it was the mode of transmission.

It’s simply a “screening tool to pick up the presence of individuals who are shedding the virus”, according to him.

Wastewater System is A “Closed System”

Speaking to The Straits Times, a spokesman from the Public Utilities Board (PUB) said that sanitary systems here are “closed systems”, meaning the pipes and airtight and watertight.

Consequently, no foul air, viruses, or bacteria can escape these pipes and spread to other households or between blocks, for that matter.

“For instance, water seals located in the U-shaped sections of underfloor pipes in the toilet bowl and floor traps for sinks, wash basins and showers act as barriers to prevent foul air that may contain bacteria and viruses from entering a unit’s premises,” he added.

Sanitary pipes are also hydraulically and air-pressure tested by licensed plumbers to ensure that there’s no leakage in the system.

These pipes were designed with a gradient, meaning the used water flows in a downward direction quickly, ensuring no backflow.

Contaminated Surfaces, Nearby Coffee Shops, or Social Visits the Real Causes

As for what caused the spread of COVID-19 from one block to another, experts had several theories.

Professor Dale Fisher, an infectious disease expert at the National University of Singapore (NUS), believes it could have been through a contaminated surface.

Or, as Prof Tambyah speculated, residents in the adjacent blocks could have visited each other, or met at a nearby coffee shop.

Mass testing at both blocks is just a precaution, however, as we cannot yet rule out the possibility of false detection.

Feature Image: momente / Shutterstock.com