What does wastewater tell you about COVID?

People shed the virus in stool whether or not they test or feel ill, so the amount in sewage shows how much is spreading in the community served by the plant — usually days before clinics see the rise. It does not count cases.

CDC National Wastewater Surveillance System · weekly · week ending 10 October 2026

COVID Levels in Puerto Rico

No wastewater sampling site in Puerto Rico reported to CDC for the week ending 10 October 2026. Check the state health department.

All states CDC wastewater ↗ Measles cases

Very High High Moderate Low Very Low

Sampling sites in Puerto Rico 0

No site reported this week.

When levels are high where you live

Stay current on vaccines for COVID-19 and flu, and RSV if you are 75+, 50–74 with risk factors, pregnant, or have an infant.
Test if you have symptoms; antivirals for COVID-19 and flu work best in the first days and are meant for people at higher risk.
A well-fitting mask in crowded indoor places and better ventilation cut the risk for you and for people around you.
Stay home when sick. Outbreak news is in our epidemic record.

What this page shows, and what it misses

CDC's weekly wastewater viral activity level for each sampling site — a treatment plant or a point upstream — compared with that site's own baseline, in five categories from Very Low to Very High. State rows count sites; CDC's own state level, on its map, weighs sites differently and can differ from what these counts suggest. Places not on a sewer system, and sites that did not report this week, are not covered. Wastewater shows community spread, not the number of cases.

Data: Centers for Disease Control and Prevention, National Wastewater Surveillance System, "CDC Wastewater Viral Activity Level for SARS-CoV-2, Influenza A and RSV" (data.cdc.gov) — public domain U.S. Government work.