Colorado ? Officials said Monday they have ruled out wastewater contamination, disgruntled workers and terrorism as sources of salmonella bacteria in drinking water that have sickened more than 200 people.

A plan to disinfect Alamosa’s municipal water system will begin today as crews start running chlorine through it, Lisa Stigall, a spokeswoman with the state emergency response team, said Monday.

The roughly 8,500 residents of the southern Colorado town won’t be able to drink the water until the chemical is washed out. That could take three weeks.

The number of cases was 217, with 68 confirmed through lab tests, said state health department spokeswoman Lori Maldonado. Nine people have required hospital treatment, and one remains in the hospital.

Test results Monday confirmed earlier findings of salmonella in the city’s tap water.

The aquifer that’s the town’s water source appeared to be fine, Stigall said. “There are many unknowns,” she said. “Many questions will be answered as they move through this process.”