On any given day next fall, 22,000 government employes will move themselves and their belongings around the country on the government's business and at the taxpayers' expense. Their travel will reach a rate of eight million trips a year with a price tag of $7.9 billion.

But said Sen. James Sasser (D-Tenn.), who based those numbers on federal budget requests, no one federal agency can say where allo those people and their things are going or whether all that travel is necessary.

"Something's got to be done to get this under control," complained Sasser, who proposed at hearings yesterday that Congress cut the federal government's ever growing travel budget by five per cent.

"You wouldn't believe it, but the Office of Management and Budget couldn't even tell me whether federal employes are flying first or second class. They don't keep any records of this," Sasser said.

The cost of federal employe travel has risen 40 percent since 1974, but inflation caused almost all that increase, Alice M. Rivlin, director of the Congressional Budget Office testified at the hearing. At the same time, "real" federal travel -- actual trips taken -- declined by 8 percent, Rivlin said.

These soaring travel costs make it more important than ever to trim the fat from the federal federal travel budget, Rivlin said.

Where and why federal workers -- including military and civilian employes -- travel is known only to their supervisors scattered throughout the federal bureaucracy, officials said yesterday.

The OMB and the General Services Administration tell agencies the travel rules and dole out advice on cost-cutting measures "but we don't follow up," said Robert Dietsch, an OMB spokesman.

"I'm not saying we shouldn't but we just don't have the manpower," Dietsch said.

About 17 percent of the trips taken by federal employes to conferences were deemed "not essential" by the General Accounting Office, in a 1977 sampling, Sasser said yesterday.

In 1976, various Defense Department agencies held 60 conferences in Hawaii, at a cost of a half million dollars, according to another GAO report cited by Sasser.

At meetings in Alaska. "I see two or three people from one agency, when one would seem to be enough," Republican Sen. Ted Stevens, told the hearing.

Even Department of Energy Secretary James Schlesinger came in for criticism from Sasser yesterday. "He's been making a lot of speeches telling other people to travel less and conserve energy," Sasser said, but "he's not practicing what he preaches," Sasser charged. According to Sasser, Schlesinger's agency has asked for $23 million for travel in 1980, up $4 million over 1979.

Energy Department spokesman Jim Merna responded that a breakdown on travel costs was not immediately available, but that "energy is very much in the news."

For instance, Merna said, "we have a speaking bureau that is inundated with requests for us to send out highlevel people to explain" the issues. In addition, there are the necessary visits to contractors, regional offices, and some 82 public hearings, and dealings with other nations that help account for the travel expenses.

Part of the increase is the result of the department's Congressionally mandated program of audits of fuel pricing arrangements around the country Merna said. Schlesinger is simply spending fuel in order to save on fuel, Merna said.

Sasser, who collected his travel information from the Office of Management and Budget, noted at the hearing a recent revelation by Sen. William Proxmire that the Consumer Cooperative Bank-Self Help Development Agency had boosted its travel budget from $150,000 for 1979 to $512,000 for 1980.

That means a total of $7,900 for every number of the permanent staff that year, "including GS5 secretaries," Sasser said.

And the Economic Development Agency has increased its travel budgt by almost 100 percent in one year, providing nearly $2,000 for every employe, Sasser said.

The costs have risen to high that "someone here on Capitol Hill is going to have to force the issue," Sasser said.