An intensive review of 14,311 District of Columbia welfare cases has shown that more than one of every four families were ineligible or being overpaid, Albert P. Russo, director of the city's Human Resources Department, reported Thursday.

Bertrell L. Hallum, the department official in charge of making the welfare payments, said the findings were a sign of progress that should be welcomed by city taxpayers.

Hallum said they are the first tangible result of the decision by Congress last year to give the department enough case workers to review welfare records every six months and weed out ineligible recipients.

He said reports of high error rates in the past were based upon statistical samples, and did not directly lead to individual removals from the rolls. Hallum told a congressional committee in March that the D.C. payment error rate in January was 8.2 percent.

Russo, at a news conference, said 157 case workers spent four months reviewing 14,311 cases -- half of those on the rolls of the program of aid for families with dependent children, the largest group of welfare recipients.

Of those, 2,313 families were found ineligible, and their benefits were stopped, Russo said. Another 1,743 families had overpayments reduced. In addition, 896 families were being underpaid, he said. Russo did not give any dollar amounts.

By Oct. 31, Russo said his department will have the entire 204 case workers authorized by Congress on duty checking welfare rolls.

Russo also announced figures confirming recent reports that narcotics abuse is increasing in the District, apparently spurred by a greater availability of heroin and other hard drugs.

New admissions to the department's treatment program in the first eight months of 1978 totaled 587, compared with 682 for all of last year, Russo said. The high point was in 1976, when 730 new cases were accepted. In 1977, the number dropped to 623. The centers have a capacity of 2,000.