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Looking for clues to the spread of coronavirus in Mass.? Try the toilet

The Deer Island water treatment plant.David L. Ryan/Globe Staff/file

With residents fervently hoping Massachusetts can avoid a flareup of the deadly coronavirus, officials are now on high alert for signs of an uptick in infections. One unusual place they’re monitoring: people’s toilets.

The Massachusetts Water Resources Authority says it is analyzing the sewage from Eastern Massachusetts at the Deer Island treatment plant through the end of the year.

The idea is that studying the wastewater could provide an “early warning system tracking trends and potentially predicting a second wave of COVID-19,” the disease caused by the coronavirus, the authority said in a recent statement.

The coronavirus pandemic, which has swept across the world, has killed more than 8,100 people in Massachusetts. The outbreak reached its peak here in the spring and is now subsiding. But dozens of other states, particularly in the South and West, are now grappling with their own surges of cases and deaths.


Last month, the authority’s board of directors approved the award of a $200,000 contract with Somerville-based Biobot Analytics Inc. for a six-month pilot study, the authority said. Biobot had conducted an initial study at the plant in early March.

Testing is now underway, the MWRA said.

“MWRA will likely use the lessons learned from this pilot program to establish a long-term program for 2021 and beyond for as long as COVID-19 continues to be a public health threat,” the statement said.

The Deer Island treatment plant, a landmark featuring giant egg-shaped “digesters” at the edge of Boston Harbor, treats wastewater from Boston and 42 other communities in Eastern Massachusetts before sending it out through a 9.5-mile-long tunnel into Massachusetts Bay.

Under the monitoring program, wastewater samples will be collected and analyzed three times a week from the wastewater flowing into the plant from the north and south of the plant, the authority said. Upstream samples will also be taken if an increased signal for COVID-19 is detected, with the goal of narrowing down where the virus is being flushed into the system.


The authority said that “studies from locations around the world have demonstrated the effectiveness of wastewater analyses to provide an early warning of COVID-19 outbreaks by up to seven days in advance of confirmed cases showing up in the public health data.”

Biobot is now working with about 400 facilities in 42 states across the US, which represents over 10% of the US population, the company said in an e-mail.

“In general, wastewater offers the opportunity to provide near real-time trend data to evaluate the impact of policy-making, early warning for second waves, and the opportunity to mass-test the US population on a regular basis at a fraction of the cost of clinical testing,” the company said.

In some other jurisdictions, including Connecticut and the Netherlands, results of wastewater surveillance are posted on websites so the public can see how things are going.

The MWRA is working to get the Biobot results up on its website, said spokeswoman Ria Convery.

Governor Charlie Baker said at a late June news conference, “We’re hopeful that this pilot can be another surveillance tool for the Commonwealth to monitor where COVID-19 exists so that we can have a more targeted approach to quickly isolate and slow the spread of any infections.”

“We do shed virus in stool. It ends up in sewage. So by monitoring sewage, you can start detecting the presence of the virus in your community earlier than the point at which cases start becoming noticed by doctors,” William Hanage, an associate professor of epidemiology at the Harvard T.H. Chan School of Public Health said last week in a Facebook Live session presented jointly by the school and The World from PRX and WGBH. Hanage was one of the coauthors of the original Biobot study.


In an opinion piece published last week in STAT, a group of experts called for a national wastewater testing program. The authors, who included Dr. Ashish Jha, head of the Harvard Global Health Institute, wrote that “we need new tools for understanding Covid-19 transmission. A national wastewater surveillance program offers a cost-effective approach to track Covid-19 across the majority of the U.S. population and provide early warnings of resurgence.”

STAT reported in May that the intriguing idea of testing wastewater had “quickly leapt to the threshold of real-world use.”

Martin Finucane can be reached at