When the City of Cambridge announced that dangerous levels of cancer-causing agents had existed in the water supply, the city was telling people at Harvard little more than they already knew.

While members of the Harvard community said yesterday that they did not know that there were high levels of carcinogenic triha-lomethanes (THMs) in the water from July, 1988 to December, 1989, they did believe that the water was unsuitable to drink.

As a result, many people around Harvard said they were already drinking bottled water when the announcement came two months ago.

Biochemistry Department worker Bob M. Sawtell, who said that Cambridge water once "turned his bathtub block," said yesterday that his department supplies bottled water to most of its laboratories.

"Anyone with half a brain knows not to drink the water." Sawtell said.

Harvard officials confirmed last week that the University would conduct its own water tests to determine if dangerous levels of THMs, known to cause cancer in laboratory animals, were still present.

Staff in departments ranging from Economics to Music also said that their offices were supplied with bottled water.

Leverett resident Patricia M. Keane '90 said that she has a Poland Springs water dispenser in her room because House Master John E. Dowling '57 "said that he won't clean biological instruments with Cambridge water, so I won't clean my teeth with it."

But physics department electrician Ralph Stanley said he was not sure that bottled water was any safer than tap water, since he discovered a great deal of pollution while cleaning out bottled water dispensers in Jefferson Hall last year.

Stanley, who said he was told by the University last year that testing the water was "too expensive," said he installed granulated charcoal filters, which remove 98 percent of THMs.

But while many at Harvard said they avoided Cambridge water because they believed it was not safe, others said yesterday that they did not drink the water simply because they did not like the taste.

Claire L. Reily, staff assistant in the language coordinator's office, said she would not "drink bottled water anyway" because city water "tastes horrible."

Many students said that they felt that, despite the availability of bottled water, there was nothing they could do to avoid exposure to the carcinogens.

Varsity volleyball athletes Esson Lin '93 and Brian C. Jones '93 said they drink a great deal of the Cambridge water during their practices, but added that they were worried about the effects of the carcinogens in the water.

"After I found out there were carcinogens, I was always thirsty," joked Geetha R. Mathew '93. "I've been drinking the water a lot."