COVID-19 Wastewater Surveillance in Montgomery County

Back to Data Dashboard

Montgomery County's Department of Health and Human Services (DHHS) is collaborating with the University of Maryland's Department of Civil and Environmental Engineering (UMD) and Inspection Experts, Inc. (IEI) to implement wastewater surveillance of COVID-19 in Montgomery County, leveraging experiences from the Maryland’s Sewer Sentinel Initiative. The project’s goal is to collect data to observe trends in SARS-Cov-2 concentrations over time.

Wastewater testing of SARS-CoV-2 (COVID-19) provides supplementary information on COVID-19 prevalence in the communities. SARS-CoV-2 can be shed in feces by infected individuals. This makes it possible to track COVID-19 through sewage testing, even for people without symptoms.

Wastewater surveillance provides an early indication of COVID-19 spread in communities. When used along with other surveillance data, this wastewater information helps public health officials take action quickly.

CDC launched the National Wastewater Surveillance System (NWSS) in September 2020 in response to the COVID-19 pandemic. Wastewater samples have been collected across the country to track the presence of SARS-CoV-2.

In Maryland, the Department of the Environment (MDE) and the Department of Health (MDH) conducted the Sewer Sentinel Initiative to monitor the concentration of SARS-CoV-2 in five wastewater treatment plants across the state. The pooled sampling approach was used to support Maryland’s response to surges in vulnerable populations and provide useful information.  See Sewer Sentinal Phase 2 Overview (PDF).

Water Sampling Protocol and Methods of Analysis

Water samples are collected by IEI weekly and sent to UMD labs for analysis. Data are then sent to DHHS.

Selection of wastewater sample collection sites was based on these criteria:

  • disease burden of COVID-19,
  • vulnerable population/communities,
  • population density,
  • areas of healthcare utilization, and
  • site characteristics (i.e., wastewater treatment plant/pumping stations/manhole, industrial effluent/hospital and nursing homes, readily available flow rate data, etc.)

The methods and criteria used for final site selection are described in Site Visit and Final Selection Report (PDF).

Protocols on water sample collection and analysis are described in Sampling Protocol - IEI (PDF) and UMD - Analysis protocol and data report (PDF)

See more information on wastewater surveillance data reporting and analytics from the CDC.

See examples of how to interpret figures (PDF).

Water Sample Collection Sites

Five sampling sites were selected based on the above criteria and analyzing the data provided by WSSC Water. Samples are obtained from each site twice per week.

The sites are

  1. Reddy Branch - 2611 Brighton Dam Rd., Brookville, MD 20833
  2. Arcola - 2001 Henderson Avenue, Wheaton, MD 20855
  3. King Farm - 315 Pure Spring Cresent, Rockville, MD 20850
  4. Hoyles Mill - 15001 Hoyles Mill Rd., Boyds, MD 20841
  5. Wexford - 21225 Seneca Crossing Dr, Germantown, MD 20876
Map of sampling sites


Data updated November 29, 2022

Figure 1. Wastewater Surveillance (Average) and Clinical Data on COVID-19, Montgomery County, MD

Graph: Wastewater Surveillance (Average) and Clinical Data on COVID-19, Montgomery County, MD

Figure 2. Wastewater Surveillance by Site on COVID-19, Montgomery County, MD

Graph: Wastewater Surveillance by Site on COVID-19