Traces of COVID-19 have been found in Rockhampton sewage, Queensland Health said on Saturday.

Routine testing returned positive results for viral fragments at sewage plants in Townsville, Nambour, and Rockhampton.

Queensland chief health officer Dr Jeannette Young said positive sewage results, collected on January 12, 18 and 19, were cause for the community to be alert, but not alarmed.

"A positive sewage result means that someone who has been infected or is currently infected, is shedding the virus," she said.

"Infected people can shed viral fragments and that shedding can happen for several weeks to months after the person is no longer infectious.

"This does not necessarily mean we have new cases of COVID-19 in these communities, but I will once again stress the need to be vigilant with any COVID-19 symptoms."

Dr Young said that those in the three relevant areas should get tested immediately if they have any COVID-19 symptoms.

"Please, get tested," she said.

"If there is a case in the community, it is critical we detect it through our testing mechanisms as quickly as possible to contain any potential spread and protect the great progress Queensland has made in recent months.

"I also want to reassure the community, local drinking water is thoroughly treated through processes that are designed to remove or kill microorganisms before they reach your taps - so there is no risk when drinking water, showering, watering the garden, swimming or other activities."