A District official, prodded by a Virginia representative, said yesterday his agency was studying the impact of the city's 18-year-old drinking age and might ask the City Council to raise the age limit.

"We are looking at the situation to determine if we should make a policy recommendation to the council," David Rivers, director of the D.C. Department of Human Services, told a House subcommittee at hearings on the city budget. "Personally, I think there is some merit" to raising the age.

The drinking age issue was raised by Rep. Frank R. Wolf (R-Va.), who said the District is "the only jurisdiction on the East Coast where 18-year-olds can buy alcohol." In Maryland and Virginia, the legal age limit is 21.

Wolf said a recent informal survey by state police indicated that a majority of the area's teen-age drunk driving arrests involve District residents or youths who have been drinking in the District.

Rivers, testifying on behalf of his agency's $541.2 million budget request for fiscal 1987, also defended his department's handling of a $671,000 school drug counseling contract awarded to Decisions Information Systems Corp., a firm headed by his friend, John Clyburn.

DISC received about $99,000 from the agency for the contract, which was canceled after a school board member alleged the awarding of it was "wired."

"This contract and the process of awarding it was above reproach," said Rivers, who said he expected a city auditor's report due out in a few days to clear up any implications of impropriety. The director said his agency had a dilemma in awarding competitively bid contracts because losing firms "charge collusion."

In a related development, a city official said yesterday that the Department of Finance and Revenue had notified the Department of Human Services that DISC owed $80,000 in back taxes and that all payments on contracts should be made directly to the revenue agency.