Union official representing the District of Columbia's teachers, firemen and police officers have bypassed Mayor Walter E. Washington, going directly to the City Council instead, to seek legislation that would guarantee them a "floor" for next year's pay increases.

Spokesmen for the unions said they went to the Council to seek the guarantee this year because of "confusion" two years ago when the unions negotiated only with the mayor.

In 1975, the mayor agreed to a two-step 18 per cent pay raise. But the Council awarded only about an 11 per cent increase over a two-year period to the city's 11,780 teachers, firemen and police officers. By city law, the Council must approve the mayor's budget requests.

Mayor Washington refused comment yesterday on two bills sponsored by Council member Marion Barry (D-at large) that would guarantee the floor for pay increases.

But he did say that "it's a rather queer sort of development seeing as how they (the unions) are still in negotiations (with the mayor's staff)" over next year's salary increases and fringe benefits.

Barry's two bills would guarantee firemen, police and public school teachers the same pay increases that federal civil servants would get under proposed federal pay raised estimated to be about 6.5 per cent during the next fiscal year.

City personnel officials, however, said the bills, which Barry estimated would cost $10 million to $12 million, would also remove the executive branch's traditional role in collective bargaining, and they questioned whether the bills would endanger current collective bargaining.

"It's difficult for us to believe that Councilman Barry would circumvent procedures mandated by public law to substitute a legislative remedy to the salary issue," said James R. Mandish, assistant director of personnel and a member of the mayor's collective bargaining team.

"I'm not sure where this leaves the city and the unions as far as current negotiations," he said.

At a press conference yesterday, union spokesmen said the legislation that Barry is sponsoring won't, in their opinion, endanger collective bargaining.

Under the current procedure for determining wage increases and benefits, union and city personnel officials conduct a survey of police and firemen's wage packages in cities of comparable size throughout the country. In the case of the teachers, the Board of Education works with city officials on the survey rather than with officials of the Washington Teachers Union.

The surveys, which include the Consumer Price Index for the Washington metropolitan area, are used as starting points for collective bargaining between the mayor and employees' representatives. This procedure was established by Congress.

"Today was to be the final meeting of the study group," Mandish said. "I haven't read the two (Barry) bills, but it seems as though the union presidents have already reached an agreement with Mr. Barry, bypassing the laws they worked so hard to get enacted" by Congress.

Even though Barry's proposed bills, which were introduced yesterday, set a floor for wage increases, the District's teachers, firemen and police officers could get even higher salaries and benefits next year in one of two ways:

The mayor, based on the as-yet unfinished surveys of wage packages in comparable cities, could recommend increases higher than the probable 6.5 per cent floor - which the Council could then raise or lower, based on the mayor's recommendation. Or the Council, acting independently of the mayor, could set salaries above the floor set by the Barry bills - assuming the bills pass the Council.

Union officials said yesterday that, based on a survey poll of all 13 Council members, the union members will receive salary increases at least equal to the floor recommended in the Barry bills.