A major airline is apologizing after one of its passengers took a sip from one of the free bottles of water aboard a flight last summer – and found herself drinking grease instead.

Passenger Sian Gani told CTV News she put the bottle to her lips during a Japan Airlines flight from Jakarta to Toyko, and suddenly tasted what she described as “gasoline.”

“Directly I felt something weird in my mouth. So I went to the washroom and tried to spit it out,” the Port Moody woman said.

It was too late – she had already swallowed it. Flight attendants called for a doctor aboard the plane, who gave her medication and she passed out, she said.

“It was a nightmare for me because I had a cough and a sore throat and then I lost my voice for about 18 days afterwards,” she said.

She asked for an investigation by the airline and the police. The airline tested the water in the bottle, which had been contaminated with a lubrication grease they called Petro Cosmo LCEP2.

An investigation found 12 other bottles with a chemical smell. They also found other passengers complaining on a second flight, which was also loaded with water bottles that day.

The airline concluded that the grease had somehow entered the container where it was bottled, in Jakarta, Indonesia.

“The airline immediately removed this item from service and from its future inventory,” Japan Airlines said in a statement to CTV News.

“Japan Airlines’ priority is the health and well-being of all our customers and to ensure that we only provide quality products onboard all of our flights. We regret that this unfortunate service irregularity occurred."

Contamination of water by grease is rare. It’s more common that water becomes undrinkable because of bacterial contamination.

Water pipes on airlines can become contaminated by E. coli. Records obtained by NBC News of inspections by the U.S. Environmental Protection Agency showed around 10 per cent of flights failed tests.

Last summer, Cathay Pacific offered its passengers free bottled water when the pipes on some 10 per cent of its planes were found to be contaminated.

But bottled water is not necessarily the safe choice, said Vancouver Coastal Health’s water specialist, Len Clarkson.

He said E. coli can grow in bottles as well in certain circumstances. Other contaminants must enter the bottles from outside, usually through the bottling process.

“Bottles can become contaminated through the manufacturing process, or the filling process, with cleaners or lubricants, or foreign material,” he said.

One famous example is a wide recall issued by Perrier in 1990 after its bottles became contaminated with benzene, a natural component of crude oil and a carcinogen.

In 2011, the Canadian Food Inspection Agency found some 13 per cent of bottles had bromate, a possible carcinogen, and 2 per cent had bromate that exceeded Canadian drinking water standards.

Clarkson said unlike bottles, tap water is continually tested, and is much less likely to contain contaminants.

“We prefer to use tap water versus bottled water,” he said.