The number of Alamosa residents with salmonella topped 200 Sunday, from 33 cases initially reported.

Of 216 reported cases so far, 68 have been confirmed by lab results, Jim Shires, spokesperson for the Jefferson County incident-management team said, according to the Associated Press. Nine people have been hospitalized, but only one was believed to still be in the hospital, Shires said.

Officials do not know when to expect the number of new cases to fall off. “Several factors go into that. We can’t say yet.”

Salmonella is a common bacterium that can cause serious and sometimes fatal infections in young children, frail in elderly people and others with weakened immune systems. Symptoms of salmonella include fever, diarrhea, nausea, vomiting and abdominal pain. Most people recover from salmonella illness without special treatment, but cases of severe diarrhea require medical attention and there’s a risk of infection spreading from the intestines to the bloodstream, a condition that could turn fatal.

Health officials believe the municipal water is the source of the problem. That’s why the water system will be flushed on Tuesday, a process that could take a week or more. Until the process is complete, residents are urged not to consume any municipal water, even if boiled, city officials announced.

According to Dr. Ned Calonge, chief medical officer for the Colorado Department of Public Health and Environment, more than 30 companies have offered to donate bottled water to the community.

The tap water is good only for bathing, as long as people are careful not to ingest it, health officials said.