Long Beach has lifted a boil water alert issued after E. coli was detected in the city's water supply.

The advisory had been in effect since Friday, when officials said E. coli was found in a sample taken from a home on Grand Boulevard.

The Long Beach Public Works Department spent the weekend flushing the system near Grand Boulevard with chlorine. The state health commissioner says additional rounds of testing confirmed the bacteria was no longer present.

Before the all-clear was given, Long Beach Public Schools made a decision to close three schools -- East, West and Lindell -- out of an "abundance of caution." The district said a student within city limits was sickened by E. coli.

The 12-year-old student's mother, Alexis Pace, says the girl -- who has Down syndrome and Crohn's disease -- was taken to a hospital and treated for dehydration. Pace says she still doesn't trust the tap water.

While doctors have confirmed that Pace's daughter was infected by E. coli, the Nassau County Health Department says it's unknown at this point whether she got the bacteria from the water or another source. That will take some time to determine.

The girl became ill last Monday, before the city's water was flushed with chlorine.