Residents of Lake Jackson, Texas, have been advised not to use tap water because it may be contaminated with a deadly germ that eats away at the brain.
The local water authority has warned of a possible contamination of its supply in the city – home to about 27,000 people – by Naegleria fowleri.
Amoeba usually infects humans when contaminated water enters the body through the nose. It is usually fatal.
Infections are rare in the US, with 34 reported between 2009 and 2018.
Eight Texas communities were told Friday night not to use the water supply for any reason other than flushing toilets. But the warning was denied on Saturday for everywhere except Jackson Lake.
The Texas Environment Committee said Lake Jackson residents should continue to avoid using tap water until the water system is adequately rinsed and samples show the water is safe to use.
He said it was not yet known how long it would last.
Naegleria fowleri is found all over the world. According to the Centers for Disease Control and Prevention (CDC) The majority of infections in the US were caused by contaminated freshwater in the southern states.
The CDC says humans cannot be infected by swallowing contaminated water and cannot be transmitted from person to person.
Those infected with Naegleria fowleri have symptoms such as fever, nausea and vomiting, as well as a stiff throat and headaches. Most die within a week.
One previously confirmed infection in the US state of Florida earlier this year. At the time, health officials there urged locals to avoid nasal contact with tap water and other sources.