Aging infrastructure contributed to an E. coli contamination of the city of Baltimore's water system in early September, officials said this week.

A confluence of events in several parts of the water system reduced chlorine levels, which led to three positive tests for E. coli, a Department of Public Works official told The Washington Post.

City officials also detailed their findings during a City Council hearing Thursday.

CDC INVESTIGATING 'FAST-MOVING' E. COLI OUTBREAK IN MICHIGAN AND OHIO THAT HAS INFECTED NEARLY 30 PEOPLE

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Baltimore officials say that E. coli contamination in the city is partially because of aging infrastructure.

The contamination led to a boil water advisory for a wide swath of the city and into Baltimore County, which is served by the city system, The Baltimore Sun reported.

MULTISTATE E. COLI OUTBREAK SENDS AT LEAST 10 TO HOSPITAL

No illnesses were linked to the contaminated water, a city spokeswoman said Friday.