The test was conducted Tuesday after 21-year-old Elisa Lam was found wedged into one of four water cisterns atop the downtown Cecil Hotel.
The county Department of Public Health has, however, issued a do-not-drink order, and only water for toilets is flowing for hotel guests.
County health official Angelo Bellomo says chlorine in the water likely killed any bacteria in the tank where Lam's body was found.
Guest complaints about low water pressure prompted a maintenance worker to make the gruesome discovery.
The cause of Lam's death has yet to be determined.