Cambridge is still drinking fluoridated water and the City Council wants to know why. Some sort of answer should come Monday night, when William H. McGinness, Superintendent of the Water Department, responds to Councillor Walter J. Sullivan's order calling for a personal report on the matter.

In a referendum in November, Cambridge citizens voted to discontinue fluoridation, 16,677 to 15,257. But a state Supreme Court decision in a Newton case this fall suggests that the November referendum has only an advisory effect and is not necessarily legally binding on City officials.

According to McGinness, the discontinuation of fluoridation is "a matter of policy" properly decided by the Water Board. He said that he had placed the case in the hands of the Board when he was told of Sullivan's order.

John F. Davis, chairman of the Water Board, said the Board has not been officially notified of the referendum vote. And according to Thomas J. Hartnett, secretary of the Election Commission, the Commission does not legally notify anyone. "I checked on that at the State House," he said.