St. Elizabeths Hospital, the federally run mental institution in Southeast Washington that has been denied full accreditation for several years because of numerous deficiencies, has won reaccreditation from a national hospital surveying group.

By passing an October survey, St. Elizabeths has been fully reinstated for the next two years by the Joint Commission on Accreditation of Hospitals (JCAH). Two-year accreditation is the maximum period granted by the commission before its surveyors return for reinspection. The hospital currently houses about 1,900 patients, most of them District residents.

JCAH withheld St. Elizabeths' accreditation between 1976 and 1979 when surveyors found numerous building safety violations, lack of recreational activities for patients and inadequate treatment plans and staff for patients. When the facility failed to correct all these deficiencies, JCAH gave it only a one-year provisional accreditation in 1980.

The latest report card, received by hospital staff early this week, restored the hospital to good graces for two years, but with one qualification: It must undergo an interim survey next October in what the JCAH called "areas of Life Safety and Therapeutic Environment."

St. Elizabeths chief executive officer William H. Dobbs said yesterday deficiencies in both of these areas involve building safety problems that currently are being corrected. They include a centrally controlled fire alarm system for all buildings on the 320-acre campus, exits at both ends of each hallway and the creation of private rooms instead of dormitories for patients.

Dobbs noted that many of the institution's buildings are more than 100 years old and do not meet modern safety standards: "That's been the case for years," he said. But Dobbs said that the continuing construction program is slated to correct the majority of these problems by 1986.

Accreditation by the Chicago-based JCAH, whose members represent major medical specialty groups, is not essential to a hospital's operation, but it lends the facility prestige to attract better staff and funds for training programs. Lack of JCAH accreditation in some cases also can stall payment of patients' bills by Medicare, Medicaid and some private insurance companies.

Dr. Herbert Pardes, director of the National Institute on Mental Health, which oversees St. Elizabeths, said yesterday the latest JCAH report is good news. "This is really a major accomplishment for the hospital . . . It is a statement to the world that certain standards of quality have been met."

Even with the hospital's new clean bill of health, the JCAH report suggested ways the hospital could improve its facilities still further: fuller and more accurate reporting on patient and personnel records, more plans for deinstitutionalizing some patients, better assessment of patient behavior and problems. Dobbs said these are only suggestions that do not affect the granting of the hospital's two-year accreditation.

He added, however, "If we consistently lose dollars and staff as we have to OMB the federal Office of Management and Budget , they JCAH could certainly come back and revoke accreditation ." The hospital's current budget is seven percent less than last year's and may be cut more in 1983, Dobbs said. In addition, hospital admissions jumped 20 percent last year, in part because of increased economic stress on city residents, he said.

St. Elizabeths' new status also comes after a critical report earlier this year by special consultant and former JCAH surveyor Stanton P. Thalberg, hired by the hospital to assess its operations. He concluded that most patients received only one hour of scheduled treatment a day, far too little for inpatient service. He also said the hospital could not account for $8.3 million in clinical staff salaries and that hospital staff was managed poorly.

Thalberg could not be reached for comment yesterday.