SARS-CoV-2 in Wastewater

As a reminder: All data are preliminary and subject to change.
Dashboard Updated: Weekly on Tuesday

COVID-19 Wastewater Surveillance

This dashboard shows wastewater surveillance data from Virginia’s Wastewater Surveillance Sentinel Monitoring Program. This program is funded by the CDC National Wastewater Surveillance System and supported by VDH.

Wastewater is collected each week from multiple wastewater treatment plants in Virginia. See current sampling locations in the map below. These samples help us track the amount of SARS-CoV-2, which is the virus that causes COVID-19, in the wastewater. VDH analyzes the amount of SARS-CoV-2 virus pieces found and using the total daily flow at the treatment plant, calculates the “viral load” (the total amount of viral pieces entering the wastewater treatment plant that day). Considering that people infected with COVID-19 can shed the virus in their feces (which then gets flushed down the toilet), VDH can track if COVID-19 infections are increasing or decreasing in the community served by a wastewater treatment plant. This community that feeds into the wastewater treatment plant is known as a “sewershed”.

There are limitations when interpreting this data. Viral loads can change for many reasons beyond how many individuals are infected in the community. These reasons can include temporary changes to the sewershed population (e.g., tourism or student towns), or changes to the virus itself (i.e., variants). This is why trends and context are important in interpreting this data.

The level of correlation between wastewater detections and COVID-19 cases is not fully understood, and researchers continue to explore this question. The data should be interpreted with this limitation in mind and should be used together with other data points.
As each sewershed is unique, VDH does not recommend comparing viral loads from one sewershed to another sewershed. Instead, consider the overall trend (whether it is increasing or decreasing) for each site, or for the entire region. For context, see the graph of the sewershed COVID-19 case numbers presented below. Ideally, the wastewater viral load trends should match up with, or even show changes a little earlier than changes in cases for that community.

COVID-19 Wastewater Surveillance Trend

This map of Virginia shows the locations and overall viral load trends of the wastewater collection sites enrolled in the Sentinel Monitoring Program. The outlines represent the Virginia Health Regions. The trend is indicated by the color of the ‘dot’. See legend below. Not all sites produce data every week, so there may be gray ‘No Trend Available’ dots. You can zoom in on the map to see the area covered by each sewershed.

Select the week you wish to view from the ‘Sample Collection Week’ dropdown menu. The default display will be the most recent week. The colors of the dots vary depending on the change in the trend from the previous week. When you hover over a sample point, a tooltip will pop up and display the following information:

  • Virginia Department of Health Region (underlined and bolded)
  • Sewershed
  • Approximate Population Served
  • Start of Sample Collection Week
  • 1 Week Trend

Note: If you select a point, click it again to deselect it.

To access this content's data tables, follow the links below:
Links open a new window.

COVID-19 Wastewater Surveillance Percentiles

There can be some variability within each site’s viral load every week, thus we determine if viral load is high (red) or low (blue) based on what we have seen in the past. What is high for one site may not be high for another. This visual is created every week to reflect whether the viral load that week is higher or lower than the viral load for that site in the past. Each sample is assigned to one of 5 groups (lowest, lower, middle, higher, or highest). It answers the question, “How high or low are current viral levels at Wastewater Treatment Plant X compared to previous sample collections at Wastewater Treatment Plant X?” ‘Insufficient data’ indicates there are not enough data points to appropriately bin the viral loads into the five categories:

  • Lowest
  • Lower
  • Middle
  • Higher
  • Highest

One year’s worth of data is presented in the chart. Use the dropdown menu to select the ‘Most Recent 6 Months’ or ‘Prior 6 months.’

Note: If you select a point, click it again to deselect it.

To access this content's data tables, follow the links below:
Links open a new window.

COVID-19 Wastewater Surveillance Viral Load and Cases

Use the ‘Pick a Health Region’ control to select a specific region. The default setting is for all sewersheds within a selected region to be displayed on the same plot. The data can be filtered down to view data for just one sewershed by clicking on the list of sewersheds. Another option is to hold the ‘Ctrl’ key down while selecting multiple sewersheds within the same region.

Note: In December 2021, the Chesapeake-Elizabeth plant was closed and all of its wastewater is now treated by the Atlantic plant.

SARS-CoV-2 Viral Load in Wastewater 

This box shows all the viral load data points for a selected sewershed.

When you hover over a sample point, a box will pop up and display the following information:

  • Sewershed
  • Approximate (Approx.) Population Served
  • Sample Type (grab vs. 24-hour composite)
  • Sample Collection Date
  • Viral Load (trillion copies/day)

Reported COVID-19 Cases within Sewershed 

This graph shows all COVID-19 cases known to VDH for the selected sewershed. Cases are presented as the number of new COVID-19 cases reported that day.

If the viral concentration is below detection, a ‘+’ sign is shown.

  • The ‘Sewershed’ legend will present the sewersheds in order of smallest to largest population.
  • Note that the scale on the y-axis will change depending on how high or low the viral loads are for the selected sewershed(s). The history goes back to the start of the Sentinel Monitoring Program, September 2021.

Note: If you select a point, click it again to deselect it.

To access this content's data tables, follow the links below:
Links open a new window.

Utility Partners

The wastewater surveillance program would not exist without the cooperation of our utility partners. Our utility partners donate staff time to collect and package the samples for shipping every week to the Virginia state laboratory, DCLS. Their support of this program is a testament to their ongoing goals of protection of public health and the environment.

Our participating facilities:

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