The water, found in the irrigation systems used for green-leaf lettuce distributed by Nunes Co., was infected with a generic form of E. coli that is commonly found in water and soil around the world, The Los Angeles Times reported Tuesday.
The strain is not thought to be dangerous, but "is used as an indicator of fecal contamination," said Dean Cliver, a food safety professor at University of California, Davis.
Experts told the Times the E. coli found in the water does not appear to be connected to the spinach outbreak, which caused three deaths and 102 hospitalizations.
"Currently there is no link between the Nunes Co. and the previous spinach outbreak," David Acheson, chief medical officer at the Food and Drug Administration's food safety center, said in the Times report.
Acheson said tests were being carried out on the lettuce to make sure the E. coli in the water is not dangerous to humans.