However, HCPH said there are no human cases of the virus in Harris County, and the source of H5N1 in the wastewater is unknown.
"The most likely source is related to agriculture, and the public risk remains low," HCPH said.
Houston is one of nine Texas cities where the virus was detected in wastewater samples between March 1 and May 13, 2024.
This comes as the city of Austin reported that it detected traces of the virus in its wastewater systems.
City officials there also said there were no human cases, and the risk to the public remains low.
READ MORE: How concerning is it if traces of the bird flu are detected in our wastewater systems?
Even though bird flu has been detected in wastewater samples in the Houston area, it doesn't necessarily mean that there are people in our communities who are infected.
Chris Van Deusen with the Texas Department of State Health Services told ABC13's Rosie Nguyen on Monday that traces of the dead virus could still be detected in milk that has been pasteurized if it came from a cow with the bird flu. If someone pours that milk down the drain, that's one way it could end up in wastewater systems.
"The way most wastewater testing is done, it's through a test called PCR. What that sort of looks for is fragments of the genetic materials in a virus. So it doesn't necessarily mean it's a live virus," Van Deusen said. "One thing that could be going on here is the milk coming from cows in another part of the state and going down the drain in our sewer systems."
He emphasized that pasteurized milk from an infected cow does not pose a risk to humans because pasteurization kills viruses and other bacteria.
The CDC recommends:
- Avoiding exposure to animal poop, bedding (litter), unpasteurized ("raw") milk, or materials that have been touched by, or close to, birds or other animals with suspected or confirmed A (H5N1) virus
- Avoiding drinking raw milk
- Taking proper precautions if you have job-related contact with infected or potentially infected birds or other animals. When exposed to an infected or potentially infected animal(s), wear appropriate and recommended personal protective equipment (PPE)
The first human case of the bird flu was confirmed in the Texas panhandle two months ago.