District officials said Tuesday that a city-owned psychiatric hospital will be without potable water until next week after a strain of bacteria that can cause a fatal illness was discovered in its water system.

Routine water tests on Sept. 26 showed legionella bacteria, which can cause Legionnaires’ disease, and pseudomonas bacteria, which can cause severe infections in people with weakened immune systems, at St. Elizabeths Hospital in Southeast Washington.

The facility’s 273 patients and 700 employees have been using bottled water, portable showers and hand sanitizer. No staff or patients have become sick, and the hospital continues to admit patients.

Wayne Turnage, the District’s deputy mayor for health and human services, said contractors are working up to 14-hour shifts while flushing the water system with chlorine. He said their work was expected to be completed Friday, followed by testing for residual bacteria that will take at least 48 hours.

The water system should be back online sometime next week, possibly as late as Thursday or Friday, Turnage said. He said officials were continuing to investigate how the bacteria entered the water system.

“When you’re without water, which is a necessary staple . . . it’s a severe challenge,” he said, adding that “staff and inpatients are holding up pretty well.”

Turnage said water problems are threatening patients’ access to hot meals, which typically are prepared on site. Dishwashers can’t be used and water can’t be boiled for cooking while the system is flushed, so the facility is bringing in meals from an outside contractor served on paper plates.

D.C. Council member Vincent C. Gray (D-Ward 7), who leads the council’s health committee, said D.C. Water determined the contamination “is confined to the specific parcel where the hospital is located, rather than the entire St. Elizabeths campus.”

He said in a statement he expects to receive a report detailing how the bacteria entered the water system and how similar issues can be prevented in the future. The water problems were first reported by Washington City Paper.

D.C. Water spokeswoman Pamela Mooring said the bacteria were related to “an issue with internal plumbing at St Elizabeths and not from our water distribution system.” She said D.C. Water consulted with St. Elizabeths staff last week to address the water problems and give advice on sampling.

St. Elizabeths nurse Tinuolu Shokunbi said nurses are working to maintain hygiene, even though persuading patients to walk outside the building to a trailer containing portable showers isn’t always easy.

“It’s difficult to work without water,” she said. “The job entails washing our hands all the time.”

Andrea Procaccino, an attorney at Disability Rights DC, which advocates for patients at St. Elizabeths, said she checked on patients Monday at the facility and saw 10 portable showers available to patients. She said “patients don’t seem upset” and no one has gotten sick.

“They’re doing the best they can with wipes,” she said.

Procaccino said patients and staff haven’t been given details on the cleanup process or the timeline for making the water system usable again.

“They’re being told it’s going to be soon, so they’re trying to hang in there,” she said.

Procaccino said some faucets had been removed from sinks because patients were using the water to wash their hands. She said she doesn’t understand why the problem hasn’t been fixed after two weeks.

“If this was at Johns Hopkins, they would have had it remediated. . . . That’s what really frustrates me,” she said. “You start to get into the issue of ‘Who cares about these people?’ They’re D.C.’s most vulnerable people and they don’t have a voice.”

According to the Centers for Disease Control and Prevention, more than 6,000 cases of the pneumonia-like Legionnaires’ disease were reported in the United States in 2016. The illness is fatal in about 10 percent of cases when people become sick, the CDC said.

“Legionella occurs naturally in freshwater environments, like lakes and streams,” according to the CDC. “It can become a health concern when it grows and spreads in human-made building water systems.”

Founded in 1855, St. Elizabeths was the nation’s first federally funded mental hospital. Many patients are criminal defendants, including those awaiting competence hearings and others found not guilty by reason of insanity.

The hospital has a history of difficulties. Patients sued over poor conditions in 1974, when the hospital housed more than 3,600 people, sparking litigation that didn’t end until 2012. In 2006, the U.S. Justice Department found that conditions at the hospital violated patients’ constitutional rights, and the District entered into a consent decree from 2007 until 2014.

An outbreak of Legionnaires’ disease struck the hospital decades ago. In 1965, when St. Elizabeths was operated by the U.S. Department of Health and Human Services, several patients died after an outbreak of what was referred to at the time as “St. Elizabeths fever.” CDC scientists discovered about 12 years later that the illness was Legionnaires’ disease.

Fenit Nirappil contributed to this report.