Twenty-nine patients at the Veterans Administration hospital in Pittsburgh have been diagnosed with Legionnaires' disease since January 2011, raising questions about the institution's safety practices.

Five of the cases "are known to have acquired the disease from the hospital," the VA said. Another eight were infected elsewhere, and the source of the infection in 16 cases cannot been determined.

The spate of illnesses has led relatives of two veterans who died after contracting the disease, a type of pneumonia, to blame the hospital.

CNN has learned that hospital officials knew they had a problem with the water system as far back as last December, but chose not to reveal that until a month ago.

That's when the hospital began turning off the water in parts of the hospital, staff and patients told CNN.

"They should have the best and utmost care than anybody else, even better than a normal civilian," said Dave Nicklas, whose father, Bill, died last month at age 87. According to his death certificate, he died of heart failure and Legionnaires' disease.

Nicklas entered the hospital last month for treatment of dehydration; the World War II Navy veteran initially appeared to be improving, but his condition reversed, his son said.

The man's doctors told the family shortly before he died that he had contracted Legionnaires'.

"I mean, they fought for their country, you know," Dave Nicklas said.

"They go to battle, they love their country and where do they go? They go to a hospital and they basically die in there."

Another Navy veteran -- John Ciarolla, 83, -- died July 18, 2011, after being diagnosed with Legionnaires' at the hospital, his daughter Maureen Ciarolla said.

Though the Korean War veteran had been living in the hospital for several months after he became unable to live on his own, the hospital said he could not have contracted the bacteria in the hospital.

When she questioned how that conclusion had been reached, she said she was told, "If he had gotten it here there would have been other cases."

"I felt guilty, very guilty, thinking he got it when I took him out the Sunday before Father's Day 2011," Maureen Ciarolla said.

The VA's problem extends beyond Pittsburgh. This week, it turned off the water in a building at its campus in Butler, Pennsylvania, 30 miles from the facility in Pittsburgh, said Amanda Kurtz, a spokeswoman for the facility.

The action was taken after Legionella bacteria were identified in a preliminary sample on Tuesday, she said in a statement. No cases of Legionnaires' have been identified in the Butler facility "as a result of this preliminary finding," she added.

The Veterans Administration would not say if any of the patients known to have been sick with Legionnaires' disease at the hospital in Pittsburgh had died, but it told the Allegheny County Health Department that one of them did, a health department spokesman said.

Legionnaires' disease, which is spread through water, is preventable and treatable.

"Being a veteran myself, I'm shocked and appalled that the VA would put their veterans in that type of situation," said Dave Nicklas.

According to data collected by the hospital and obtained by CNN, hospital water over the past year did not contain enough disinfectant to prevent Legionnella bacteria from reaching dangerous levels.