When the word percolated through District of Columbia police headquarters yesterday, the rank-and-file reaction was one of frustration and dismay.

No more drinking coffee on the job, came the word from on high, and no more eating lunch or reading the newspaper at your desk if the public can come in and see you.

The order, it was said, came from Mayor Marion Barry himself -- part of the new mayor's effort to impart a new and vigorous image of municipal workers, police officers and civilians alike.

It was passed along by word of mouth yesterday after a staff meeting conducted by Police Chief Burtell W. Jefferson.

The only problem, mayoral press secretary Florence Tate said last night, is that the report largely was untrue. Jefferson could not be reached for comment.

The mayor told 41 high-ranking city officials last Wednesday, his second day in office, that he wanted to discourage eating and reading by receptionists and others in ghighly visible positions, like those behind counters at the tax office and the water department. But he issued no general order.

Barry, who lunched yesterday on a bowl of beef stew at his desk, said through press aide Tate that he "expects people to respond reasonably -- if they can't go out to eat, naturally they have to eat at their desks."

As for coffee or a soft drink in public, that's okay, too, as long as the employe is working and not loafing while drinking it, Tate said.

Employes went home last night from police headquarters in the Municipal Center at 300 Indiana Ave. NW without hearing the accurate word from the mayor's office.

Their main conversation in elevators and corridors was whether the investments by various offices in electric coffeemakers was going down the drain. One employe asked another where he could carry a sandwich purchased in the building's carryout.

Barry's discussion of employe eating habits with the top officials also extended to the length of lunch periods, typically 30 minutes in the D.C. government.

The mayor said he wanted employes to take only as long for lunch as they are allowed, but added that he was willing to extend lunchtime another half hour if that were necessary. But, he said, he also would extend the workday by 30 minutes.