FLORAL PARK - With the heat wave in full swing, thousands of residents in Nassau County are being warned to boil their water following the discovery of traces of the E. coli bacteria Monday.

Some 22,000 households and businesses in seven different communities are being advised to boil water before using it. Those communities include North Valley Stream, Elmont, Floral Park, Franklin Square, New Hyde Park, Stewart Manor and Garden City.

The Water Authority of Western Nassau says secondary tests for E. coli came back negative, but other bacteria were found in the water.

Officials say test results take 18-24 hours to come back, which is why some residents didn't get a warning until today.

The Water Authority's chief engineer, Robert Swartz, says E. coli may not have been in the actual water supply, and that there are many ways a test could have come back positive.

The Nassau County Health Department conducted its own tests, which showed no contamination. However, health officials say another round of testing is required before they can lift the boil water advisory.

Boil water advisory issued for western Nassau County

Water Authority of Western Nassau County