British tourist Michael Baugh and his wife said water had only dribbled out of the taps at the downtown Cecil Hotel for days.
On Tuesday, after showering, brushing their teeth and drinking some of the tap water, they headed down to the lobby and found out why.
The body of a Canadian woman had been discovered at the bottom of one of four cisterns on the roof of the historic hotel near Skid Row. The tanks provide water for hotel taps and would have been used by guests for washing and drinking.
"The moment we found out, we felt a bit sick to the stomach, quite literally, especially having drank the water, we're not well mentally," Michael Baugh, 27, said.
Los Angeles County Department of Public Health officials issued a do-not-drink order Tuesday while its lab analyzes the water, said Allen Solomon, a spokesman for the department. The disclosure contradicts a previous police statement that the water had been deemed safe.
Solomon said the water was also used for cooking in the hotel. Results of the testing were expected Thursday.
The remains of Elisa Lam, 21, were found by a maintenance worker at the 600-room hotel that charges $65 a night after guests complained about the low water pressure.
Police detectives were working to determine if her death was the result of foul play or an accident.
Lopez called it suspicious and said a coroner's investigation will determine Lam's cause of death.
Before she died, hotel surveillance footage showed Lam inside an elevator pushing buttons and sticking her head out the doors, looking in both directions. She was later found in the water tank.