How CDC Wastewater Surveillance Is Tracking Respiratory Viruses Across the U.S.

Why sewage is part of U.S. respiratory virus tracking in 2026

If you’ve checked a CDC dashboard lately and seen data from “wastewater,” you might wonder what sewage has to do with your family’s health.

The short answer: quite a lot.

The Centers for Disease Control and Prevention (CDC) now uses wastewater—water that flows from homes and businesses into treatment plants—as part of its National Wastewater Surveillance System (NWSS). By measuring viral genetic material in sewage, public health officials can spot rising community spread of respiratory viruses like COVID-19, influenza, and RSV before clinics and hospitals report a surge.

It’s not a personal test. It won’t tell you if you’re infected. But it can serve as an early community-level signal—especially during the 2025–2026 respiratory virus season.

What Is the National Wastewater Surveillance System?

The CDC launched the National Wastewater Surveillance System (NWSS) during the COVID-19 pandemic and has since expanded it. According to CDC’s NWSS overview, the system partners with state, local, tribal, and territorial health departments to collect wastewater samples from treatment plants across the country.

Those samples are tested in laboratories for fragments of viral genetic material (RNA). Instead of identifying individuals, labs measure overall levels and trends within a community served by that treatment facility.

Today, CDC’s respiratory virus wastewater dashboard tracks:

SARS-CoV-2 (the virus that causes COVID-19)
Influenza A and B
Respiratory syncytial virus (RSV)

CDC has also explored wastewater tracking for other pathogens in different contexts, but the national respiratory dashboard focuses on these major seasonal viruses.

How Wastewater Testing Works (Plain-Language Science)

When people are infected with certain viruses, they shed viral particles in stool and other bodily fluids—even if they have mild or no symptoms. That material ends up in wastewater.

Here’s what happens next:

Wastewater treatment plants collect routine samples.
Laboratories concentrate the samples and test them for viral RNA.
Results are reported as trends—rising, stable, or falling—rather than as individual counts.

Importantly, the system focuses on direction and change over time, not exact case numbers. Weather, dilution from rainfall, and laboratory variation can affect measurements, so public health experts look at patterns rather than single data points.

What the CDC Respiratory Virus Wastewater Dashboard Shows

The CDC’s Respiratory Virus Wastewater Dashboard presents national and regional trend categories for COVID-19, influenza, and RSV. Instead of reporting “cases,” it shows relative levels and percent changes over time.

Users can view:

National trends
Regional patterns
Changes compared with previous weeks

Not every county participates. Coverage depends on which wastewater treatment plants and health departments are part of NWSS. Some rural or smaller communities may not have local data available.

Why Wastewater Levels Often Rise Before Hospitalizations

One of the key advantages of wastewater surveillance is timing.

A CDC analysis published in MMWR found that increases in wastewater viral levels often precede increases in emergency department visits and hospitalizations. In other words, sewage data can act as an early warning signal.

There are several reasons:

People shed virus before or early in symptoms.
Some people never get tested but still contribute to wastewater signals.
At-home testing results are not always reported to health departments.

A peer-reviewed study indexed in PubMed similarly found that wastewater signals can rise days to weeks before reported case surges, depending on the virus and community testing patterns.

This doesn’t mean wastewater replaces clinical data. Instead, it complements hospital, lab, and outpatient surveillance.

What Wastewater Data Cannot Tell You

It’s just as important to understand the limits.

No individual diagnosis: Wastewater data cannot tell you if you personally have COVID-19, flu, or RSV.
Not universal coverage: Not all counties or treatment plants participate.
Environmental variability: Rainfall, industrial discharge, and population changes can affect measurements.
Laboratory differences: Methods are standardized as much as possible, but variation exists.

CDC emphasizes that wastewater data should be interpreted as one piece of the broader surveillance picture—not a standalone metric.

How Health Departments and Schools Use These Signals

Public health agencies use wastewater data for preparedness and communication. For example:

Hospitals may review staffing and bed capacity if trends rise.
Health departments may reinforce vaccination messaging during upticks.
Schools may review ventilation practices or remind families to keep sick children home.

Because wastewater trends can rise before hospitalizations increase, communities have more lead time to prepare.

How Families Should Interpret Wastewater Trends

If wastewater levels are rising in your area during respiratory season, it doesn’t mean you’re certain to get sick. But it may signal that community transmission is increasing.

Here’s how to use that information responsibly:

Stay up to date on recommended vaccines for COVID-19 and influenza; RSV immunization options are available for certain age groups.
Be alert for symptoms such as fever, cough, sore throat, shortness of breath, or unusual fatigue.
If you’re at higher risk—older adults, pregnant people, people with chronic conditions, or those who are immunocompromised—seek testing and medical advice promptly if symptoms develop.
Consider layered precautions (improved ventilation, masking in crowded indoor spaces) during periods of rising activity, especially if you or household members are high risk.

Also check other indicators, including CDC’s respiratory virus activity reports and local hospital trends. Wastewater works best when interpreted alongside clinical data.

Why This Matters Beyond COVID-19

Wastewater surveillance has evolved from an emergency pandemic tool into an established public health monitoring system. As noted in reporting from CIDRAP, CDC expanded wastewater tracking beyond COVID-19 to include additional respiratory viruses, reflecting its broader role in infectious disease surveillance.

For everyday readers, the takeaway is simple:

Wastewater data is an early warning system.
It helps communities prepare before hospitals feel strain.
It does not replace personal testing or medical care.

You may never see the sampling equipment or lab reports—but when public health officials communicate about rising trends, wastewater is often part of the reason they knew early.

Used wisely, it’s one more tool helping communities stay informed and respond in time.

Sources

This article is for general informational purposes only and is not medical advice. Research findings can be early, limited, or subject to change as new evidence emerges. For personal guidance, diagnosis, or treatment, consult a licensed clinician. For current outbreak or public health guidance, follow your local health department, the CDC, or another relevant public health authority.