A District-owned psychiatric hospital is entering its fourth week without potable water after a potentially harmful bacteria in its water system survived cleanup efforts.

St. Elizabeths Hospital in Southeast has been without potable water since the legionella bacteria was found during routine testing Sept. 26. The hospital has used bottled water for drinking, bathing and cooking ever since. No staff members or patients have become sick.

City officials announced earlier this month that they had hired contractors to remediate the problem. The work — flushing the water system with chlorine — was to be completed Oct. 11, and testing for residual bacteria was to last two days.

Wayne Turnage, the city’s deputy mayor of Health and Human Services, said in a statement late Thursday that testing continued to show legionella within the hospital’s water system.

“After super chlorination of the water system, test results showed evidence of remaining bacteria,” he said.

Turnage said the water system was being treated Friday in a process that will continue through the weekend. Potable water will return “when test results show the water is safe to use,” he said, although officials didn’t give a precise date.

City officials didn’t respond to questions about how the bacteria survived the treatment.

Andrea Procaccino, a staff lawyer at Disability Rights DC, which advocates for patients at St. Elizabeths, said she spent hours Friday visiting with patients there. She said that portable showers aren’t accessible for patients in wheelchairs and that many older patients are unwilling to use them.

The showers are outside, she said, and some women don’t feel safe walking to them or bathing with male security guards nearby. Some patients are being kept on locked wards longer than usual because common areas where art and group therapy are held don’t have water, she said, and others haven’t showered in weeks.

“It’s now been 22 days that patients and staff cannot shower, wash their hands or drink the water,” she said. “I’m worried they don’t have a Plan B here. What if it’s just positive again? Are they going to move people?”

City officials say it’s not clear how the bacteria got into the water system. Rayna Smith, chief of staff for Turnage, said the cause of the problem is under investigation.

“We’re working to get the issue resolved as soon as possible,” Smith said. “As soon as test results determine that water is safe for consumption, we will immediately return to normal operations.”

Advocates said they were frustrated that it took the city several days to start remediation. Patients are receiving hot meals served on paper plates from an outside vendor because dishwashers can’t be used as the water system is being flushed.

The psychiatric hospital has 273 patients and 700 employees. Some patient advocates have expressed concerns that St. Elizabeths continues to admit patients as it struggles with water accessibility.

Along with legionella bacteria, which can cause Legionnaires’ disease, the routine testing of the water system revealed pseudo­monas bacteria, which can lead to severe infections in people with weakened immune systems.

More than 6,000 cases of the pneumonialike Legionnaires’ disease were reported in the United States in 2016, according to the Centers for Disease Control and Prevention. The disease is fatal in about 10 percent of cases where people get sick, the CDC said.

Many St. Elizabeths patients are criminal defendants, including those awaiting competency hearings and others found not guilty by reason of insanity. The hospital has a history of problems, beginning decades before the District took it over in 1987.

In the 1970s, patients sued over poor conditions. In 2006, the Justice Department found that the hospital’s conditions violated patients’ constitutional rights, and the District entered into a consent decree from 2007 until 2014.

In 1965, when St. Elizabeths was run by the U.S. Department of Health and Human Services, several patients died after an outbreak of what was then called “St. Elizabeths fever.” About 12 years later, CDC scientists figured out that the illness was Legionnaires’ disease.