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Blog Post · April 13, 2020

Wastewater Treatment Kills Most Pathogens, Including COVID-19 Virus

Photo of Municipal Wastewater Treatment Plant

Californians reuse treated wastewater as a water supply, to irrigate crops, and to support freshwater ecosystems. To get answers to questions about managing the new coronavirus in the “sewershed,” we talked to two experts: Kara Nelson, an expert in waterborne pathogens at UC Berkeley; and Adam Link, executive director of the California Association of Sanitation Agencies.

PPIC: What risks does COVID-19 virus pose in wastewater?

Photo - Kara Nelson

Kara Nelson

KARA NELSON: We now have evidence that infectious coronavirus is excreted in the feces of infected individuals. The good news is that in the US, we already assume wastewater is full of high concentrations of infectious organisms like viruses, and we have practices in place to deal with them—including ways to protect workers from exposure. Coronaviruses have a different structure from the viruses we usually worry about in wastewater, such as hepatitis A and norovirus—and that structure likely makes it easier to kill. This gives us a high degree of confidence that we have effective treatment to manage the COVID-19 virus. So yes, there are risks, but all the information we have suggests that our existing practices reduce the risk to very, very low levels.

PPIC: Is the virus a risk in the reuse of treated wastewater?

KN: Producing safe, reusable water from wastewater already requires removing pathogens from it. While existing treatments—which are based on science and a regulatory approach developed over many decades—are likely sufficient to deal with coronavirus, we would like to see research that confirms this. Studies have already been launched in California and elsewhere to ensure measures we have in place are sufficient.

The heightened public interest in the virus provides professionals in the water industry an opportunity to share information about why reusing treated wastewater is safe and why we have a very high degree of confidence on how these risks are being managed.

PPIC: What’s the story with “flushable” wipes?

Photo of Adam Link, California Association of Sanitation Agencies

Adam Link

ADAM LINK: This was already a significant issue for us, and the pandemic has brought a huge new influx of wipes and cleaning-product debris into the system. Some wipes are marketed as flushable but don’t actually break down the way toilet paper does. They can sometimes form sizeable sewage blockages that damage pumping infrastructure, cause overflows, and increase our capital costs. CASA and many of our members are engaged in public information campaigns on the problem. Our agencies are working around the clock to keep systems functioning properly and prevent major breakdowns.

PPIC: Do you foresee any long-term impacts from the pandemic for the wastewater sector?

AL: In some ways we are similar to a business, and we have to think about the potential financial impacts of a recession on our systems. There are new orders to not terminate service if payments don’t come in, and we’re likely to see more people who struggle to pay their bills as a result of the financial downturn. So we need to put thought into planning for a new financial future. Our agencies are very good at long-term planning for capital projects, but it remains to be seen how dramatically this will change things from our current expectations. Much depends on the level of stimulus and how quickly things get back to normal.

PPIC: What gives you hope right now?

KN: The agencies and their workers—they’re putting their responsibility to deliver essential services first, before themselves, just like health care workers.

I’m also impressed with how quickly the research community has responded with new research on coronavirus and water. Therapies, tests, and vaccines are obviously the immediate priorities, but water researchers around the world have kicked into high gear to find long-term strategies to fight this and other emerging viruses. One exciting development is a global effort to monitor wastewater for the virus to quickly assess its prevalence in the sewershed; this could potentially help determine if infections are reemerging so we can respond quickly to contain them.

AL: I’m very encouraged by how well our agencies have come together to solve the new problems the pandemic raises and prepare for the worst together. There haven’t been any significant disruptions—and that’s thanks to the lengths these people go to keep the public safe.


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