Almost half of a group of 69 candidates for firefighter jobs in Washington have failed urinalysis tests for drug use in the past few weeks, according to fire department sources.

In addition to delaying the hiring of new firefighters for the understaffed department, the results could jeopardize the city's ability to comply with a recent congressional directive to spend $1.2 million to reactivate four rescue squads abolished in cost-cutting moves.

Two of the squads, each of which contains 21 firefighters, are now scheduled to be fully operational in July. Two more would become active this fall, department officials said.

The recruits, who are needed to replace veteran firefighters scheduled to join the elite rescue squads, failed the tests during routine exams given on Tuesday and on May 17 and May 19, according to the sources.

A spokesman for D.C. Fire Chief Theodore Coleman, who was sworn in on Thursday after serving as acting fire chief for the past 15 months, declined to comment on the results of the tests but said none of the recruits have been formally rejected.

City budget director Elizabeth (Betsy) Reveal said yesterday the District has set aside money for the rescue squads and is "making a good-faith effort" to fill the firefighter slots.

The test results are the first indication that the fire department is having drug-related problems in hiring new recruits. The D.C. police department has said drug use among citizens is a growing impediment to hiring police officers. Last year, five police recruits were suspended after taking urine tests.

According to city officials, the D.C. Office of Personnel sent 196 letters on May 1 and May 19 to persons who had passed the fire department's last written entrance exam, which was held in November 1980.

Fire department sources said that of those who were sent letters, 69 recruits showed up for the physical exams and that 34 of them failed the urinalysis test. An undetermined number of recruits also took physicals on Thursday, sources said, but the results could not be determined immediately.

William Mould, president of union local 36 of the International Fire Fighters Association, said yesterday the results were an indication that the city has failed to aggressively recruit employable candidates for the department. Mould said the 1,300-firefighter department is understaffed by about 125 fire fighters.

"The test results should be a concern of everybody. It appears the D.C. Office of Personnel, by curving the test in 1980, has led to the problems that we are facing now," Mould said. "The test was given in 1980. They have had enough time to get the people on board in a timely fashion."

In 1980, 972 persons took the exam and 958 passed it, a record number. Of those, about 139 have been hired.

The four reactivated rescue squads would replace four units that now serve double duty, responding to fires and rescue calls. A department study in 1980 said the split duties jeopardized the department's ability to respond quickly to disasters. City firefighters lobbied Congress to reestablish the units, and money was set aside in the fiscal 1983 budget.