There is a secret house in the District where dying men can live in peace.

The Schwarz house is located on a quiet street; it has a garden and five bedrooms, and for a few men with AIDS it is a refuge from the punishing financial burdens that often accompany the fatal disease.

"I have nothing left," said one of the five men currently living in the house, which is operated by the Whitman-Walker clinic and was named for the first head of its AIDS Education Fund. "There is just no money. If I wasn't here I'd be on the street."

The direct medical costs of AIDS (acquired immune deficiency syndrome) can be catastrophic for even the most prosperous and well-insured patients. About 90 percent of the victims are between the ages of 20 and 49 and many of them have no savings. A few scrape by on Social Security payments.

Without a job or a home and unprepared for death, many AIDS patients wither away in expensive hospital beds -- either as patients of publicly financed hospitals or charity cases in private hospitals -- because nobody else is willing to care for them.

Public Health Service officials say that the cost of treating AIDS patients, from diagnosis to death, can range from $30,000 to $140,000, depending largely on how long they remain in the hospital. With the number of reported cases now doubling every 10 months, the costs of care will increasingly place a huge economic burden on patients, their families and the health-care delivery system. Currently there are more than 12,000 reported cases of AIDS in this country and researchers say that number could exceed 250,000 by the end of the decade.

The establishment of the Schwarz house is an attempt to help AIDS patients and take some of the pressure off the health-care system, according to administrators. It is the only such house in this area and one of only a few in the country. The house operates on an annual budget of $35,000, largely made up of contributions, and the location is a closely held secret because clinic officials fear that neighbors would complain or move against it, as has happened in other cities.

In order to maintain private control of the home, the Whitman-Walker clinic put together a syndicate of local residents who donated money to buy the house and then leased it to the clinic. The syndicate's charter requires that no fewer than two AIDS patients be included as voting members of the board of trustees.

"We tried to rent a place but people kept pulling out at the last moment," said Jim Graham, director of Whitman-Walker, a center that provides social services to homosexuals. "You have people living on $220 a month. They are too healthy to live in a hospital and too sick to work. This is a problem that thousands of people are going to face. Where are they supposed to go?"

Some medical experts say that facilities like the Schwarz house will become essential if the cost of treating AIDS victims is to be held in check or lowered.

In the Washington area there are a few hospices and residences where people with AIDS can go, but the Schwarz house is the only home that functions as a place for AIDS sufferers to live as normally as possible. The others are designed to give nursing care to terminal AIDS victims about to die.

There have been few attempts at assessing the potential financial impact of AIDS, and those assessments indicate that the direct medical costs alone will run into billions of dollars by the end of the decade. The indirect impact on the economy is much more difficult to gauge.

"I think that before this situation gets better, we will have to set up some sort of emergency fund to deal with the costs of this disease," said Dr. Richard Di Goia, who has treated many AIDS patients in the District. "But right now, I can't see the Reagan administration wanting to do that."

Researchers at the federal Centers for Disease Control in Atlanta have said that the average cost of treating the first 9,000 patients will be $140,000 from diagnosis to death. In a report released this spring, the CDC said that AIDS patients had spent more than 1.5 million days in the hospital at an average cost of about $830 a day. That adds up to more than $1.25 billion.

Last month, Dr. Paul Volberding, head of the AIDS program at San Francisco General Hospital, told a House of Representatives subcommittee that if only 5 to 10 percent of those exposed to the virus that causes AIDS later get the disease, direct medical care costs alone could exceed $10 billion. Some experts believe that as many as 25 percent of those exposed to the HTLV-3 virus could eventually develop AIDS.

Public health officials say that the appropriate response to the huge rise in costs would be a coordinated system of outpatient services, particularly housing programs that would allow people with AIDS to live somewhere other than in a hospital.

"I told Mayor Edward Koch that for what he was spending on people in the hospital I could put them in a private room at the Plaza and throw in round-the-clock nursing care," said Rodger McFarlane, a professional hospital administrator who recently resigned as executive director of New York's Gay Men's Health Crisis. "We're throwing this money down the toilet."

The wide range in the cost of treating patients reflects the disparity in programs throughout the country. In San Francisco, for example, the average hospital stay for an AIDS patient is 12 days, mostly because the city has the best system in the country of housing referral and outpatient services for AIDS victims. Average treatment cost there is about one-fourth the cost in New York City, where people with AIDS must spend an average of more than 50 days in the hospital because of the shortage of support programs. The hospital costs in New York average more than $100,000 per person.

Local hospital officials said they have not yet compiled comprehensive data on the average cost of treating an AIDS patient and the average hospital stay.

At George Washington University Medical Center, which has treated the largest number of the District's AIDS patients, the average cost per stay is more than $18,000, according to the hospital administrator. For many patients who repeatedly undergo expensive examinations, the costs are far higher.

District health officials estimate that by September 1986 there will be more than 1,000 AIDS cases in this area. Although no official financial projections have been done locally, doctors and hospital administrators are worried that the strain could become profound.

"I see this as a very scary situation," said Michael M. Barch, administrator of the GWU Medical Center. "We are using sophisticated diagnostic tests on AIDS patients. The medicine is mostly state of the art and the most expensive. If we don't scale down the costs it will hurt the hospital very badly."

Ironically, as new treatments come along that will enable patients to live longer after they have been diagnosed, the problems of long-term care will probably become more acute. Health insurance normally pays for only about 25 percent of AIDS treatment -- often because as people get too sick to work they lose their coverage -- and the government must pick up the rest of the tab.

"What we need are better social support and counseling services all around the country," said Deborah A. Newmark, a clinical social worker at the National Institutes of Health. "Everyone is running around saying how bad these people have it, but nobody is doing much to make it different. No matter how many selfless declarations we make, this disease is spreading and people are looking out for themselves," she said.