Viruses are constantly circulating in society. Monitoring viruses in wastewater helps to understand how infections are spreading and can even provide early warning of new disease outbreaks. In recent years, simple and low-cost tools called passive samplers have become very useful for monitoring wastewater samples from specific locations. These devices sit in the water and gradually capture virus particles over time. However, scientists still don’t fully understand how quickly different viruses are captured by these samplers, or how long the samplers should be left in place to give the most accurate picture of what’s circulating in a community. This uncertainty makes it harder to interpret results and compare virus levels over time.

To address this, researchers from PDPC Frontrunner 5: Integrated early-warning surveillance methods and tools examined how several common wastewater viruses are captured by a type of commonly used passive sampler made from membranes with a negative surface charge. The viruses studied included two often-used test subjects (the plant virus ‘Pepper Mild Mottle Virus’ and the ‘CrAssphage’ virus that infects bacteria) and four pathogenic human viruses (Human Adenovirus 40/41, Norovirus, Enterovirus, and SARS-CoV-2).

Researchers found that, for up to 48 hours, the amount of virus captured generally increased in predictable ways. However, not all viruses behaved the same. Human Adenovirus 40/41 accumulated on the membranes more strongly than the other viruses when the samplers were left in place for 24–48 hours. With shorter sampling times, these differences were smaller. This means that how long a sampler is deployed can influence which viruses appear more abundant in the results. Some viruses may for example be captured more efficiently than others, which can affect how accurately wastewater measurements reflect which viruses are actually circulating in the community.

Overall, the study shows that understanding how different viruses are captured by passive samplers is essential for designing reliable wastewater monitoring programs. Sampling strategies, including deployment time and data interpretation methods, need to account for these differences to avoid bias and ensure sensitive detection of various viruses. The researchers recommend that future studies should compare different types of passive sampling materials (such as cotton-based materials or activated carbon) to see how well they capture viruses with different properties. This will help make wastewater surveillance even more reliable as a public health tool.

The study was performed by researchers from the Pandemic and Disaster Preparedness Center (PDPC), and was first published on January 23, 2026 in ACS ES&T Water:

Sener, A. E., Heijnen, L., de Graaf, M., Langeveld, J., & Medema, G. (2026). Uptake Kinetics of CrAssphage, PMMoV, Human Adenovirus 40/41, Norovirus GII, Enterovirus, and SARS-CoV-2 on Electronegative Membrane Passive Samplers. ACS ES&T Water.

Read the full publication here.