More than 1,800 government employes in the Washington area will lose their federal jobs or be reassigned over the next two years if a series of General Services Administration reviews shows it is cheaper to have area maintenance and custodial work contracted out to private companies.

The review of 1,834 federal jobs at 23 area locations is part of the Reagan administration's emphasis on finding ways to cut costs by having private contractors take over work now done by federal employes.

More than half of the affected jobs--995--are in Virginia; another 631 employes work in the District and 208 work in Maryland. Jobs now done by federal workers that could go to private contractors include cleaning the halls of the Central Intelligence Agency, maintaining heating plants for federal agencies located along the Mall and keeping the elevators running in the White House.

GSA already has contracted out 230 area jobs, most of them at the Franconia Stores Depot, a government warehouse that will be taken over by ARA Services Inc. in December under a contract that will save the federal government an estimated $5 million over three years. All 122 employes at Franconia will be transfered to other positions in the Washington area or will have the right to work for ARA.

"Wherever possible we are going to try to preserve the jobs that employes now have by giving them transfers to other vacancies in the area," said GSA regional administrator William F. Madison. But some union officials at GSA have grumbled that the agency will not always have vacancies because the program is set to move faster than the 10 percent annual attrition rate.

Regional program supervisor Amy Swartz said the review "does not mean, automatically, that the government's employes are out (because private firms are less costly.)"

However, in the nine reviews that have been conducted at GSA so far, private contractors have prevailed eight times. No one has been fired so far, Swartz said.

The reviews were developed, in part, because federal salaries for some jobs were eclipsing similar pay in the private sector. Federal pay scales are fixed by the Office of Personnel Management.

For example, OPM requires that a starting electrician be paid $10.94 an hour while the Labor Department believes the minimum wage rate in the area is $10.44 per hour. When fringe benefits are added, the comparison is estimated at $10.76 for the private sector compared to a $13.78 rate for the GSA employe. Federal employes also get longer vacations and are harder to fire, government officials said.

"The contractor has a flexibility that the government does not have to do the job," said GSA procurement specialist Shirley Bruce. "We cannot fire those who do not perform well."

GSA has also hired pest control firms, landscapers and a maintenance company as a result of reviews that have shown it is cheaper to contract out that work. In a review, GSA compares its costs with sealed bids submitted by contractors: if the lowest bid undercuts GSA's estimate by 10 percent, the firm wins the one- to three-year contract.

In the maintenance contract, Halifax Engineering, Inc., said it could do the same work that 59 employes were doing for two-thirds of the cost. In a landscaping contract for the Pentagon, Custom Environmental Services, Inc., said it could keep the Defense Department's sprawling complex groomed for just 25 percent of the government's cost.