RIO DE JANEIRO >> There’s a creeping sense of alarm in Rio de Janeiro after more than a week of foul tasting and smelling tap water in dozens of neighborhoods. Rumors are flying, and residents are hoarding bottled water.

People in the metropolitan area have taken to social media to show glasses of water that appears reddish or brownish. Several supermarkets visited by the Associated Press today had run out of bottled water.

There have been rumors — denied by officials — that the state water utility, Cedae, would cut off supply of water to millions of residents, or that tests have determined the water unfit for consumption.

Mariana Bretas, 29, received a viral text message saying people must plug their ears with cotton when showering.

“I don’t know if it’s true, but we’re getting scared,” Bretas said after buying five liters of water.

Cedae has said the peculiar water is due to geosmin, an organic compound that is innocuous, and that the water meets health ministry requirements. Even so, it said it will begin using powdered activated carbon at the start of treatment to curb geosmin.

At a press conference on Wednesday, Cedae officials reiterated that geosmin was the cause of the smell and taste, and insisted there was “nothing alarming” about its levels in the city’s water reserves.

The number of cases of diarrhea, gastroenteritis and vomiting in two health clinics of Rio’s west zone doubled between Dec. 20 and Jan. 5 over the same period last year, but it’s too early to associate higher incidence of symptoms with contaminated water, particularly after holiday season parties, the state health secretariat said in an emailed statement.

Rio Gov. Wilson Witzel’s patience has worn thin; On Tuesday night he called for analysis of the water’s quality as well as of the utility’s management.

“The disorder the population has been suffering due to the problem with water provided by Cedae is inadmissible,” Witzel said on Twitter. “The company (Cedae) must accelerate its ultimate solution to improve water quality and sewage treatment in cities near the springs. The consumer cannot be harmed.” Maurício Oliveira da Silva, a 51-year-old resident of Complexo de Alemao, a group of slums in Rio’s north zone, said colored water had been coming out of the tap for several days until it improved on Wednesday. Still, he accused the government of lack of interest in some of the state’s most desolate areas.

“We feel abandoned,” da Silva said, adding that poorer folks like himself couldn’t afford to buy gallons of bottled water. “We feel powerless.” As for the water’s color, Cedae officials on Wednesday attributed it to the piping systems of individual homes, something for which the company can’t be held responsible.

“In my house, I always drink Cedae’s water,” the company’s president Helio Cabral assured journalists.

Cabral denied media reports that the head of the water treatment station that provides water to Rio’s Baixada Fluminense area had been dismissed. It said he’d merely changed departments under a previously scheduled move.

The facility is one of the largest in the world and receives water from the Paraiba do Sul River, but also several sewage-contaminated streams, which Cedae does an insufficient job of treating, said Joao Paulo Machado Torres, a professor of environmental biophysics at Rio’s federal university who has previously studied the city water system.

“Service is so bad that the situation is unhealthy,” Torres said.

At one market in Rio that still had supply of water, Natalia Villas Boas, a 65-year-old dentist, filled her shopping cart with 38 liters of bottles.

“People are saying the water is contaminated and it has a very weird smell,” said Villas Boas. “I don’t want to risk getting any infection.”