Simply stated, the mortgage situation in Metropolitan Washington is bad and due to get worse.

A survey of banks, savings and loan associations and mortgage bankers by two research firms plus interviews with lenders reveal these disquieting facts:

- Three-quarters of the lenders in the District have shut their windows, even to applicants willing to put 20 percent down. Those making loans on smaller down payments can be counted on one hand. A major problem is the city's 11 percent interest rate ceiling on mortgages at a time when lending in the suburbs or elsewhere brings a greater return for lenders; the D.C. City Council is considering "emergency" legislation to boost this ceiling to 15 percent although lenders prefer abolishing the ceiling altogether.

- Within the past month, the share of Virginia banks and thrift institutions that will deal only with long-standing customers has doubled to 25 percent.

- True interest rates have climbed approximately half a percentage point in the past month to where the least secured mortgage loan is now about 12 percent. Many leading institutions are requiring "points" - mortgage surcharges paid by home sellers and buyers - before they will sign a mortgage agreement.

"The financial market has collapsed, for all intents and purposes," said Larry Brown, sales manager for Long and Foster's office at 4200 Wisconsin Ave. "We are having problems putting together transactions because of lenders being extremely tight and demanding in their requirements, which in most cases affects older homes. The requirements have been unrealistic."

Walter E. Preston, editor of Builders, Bankers and Realtors Inc., a weekly status report of Maryland lenders, predicts that interest rates in that state will hit 13 percent in the next 30 to 60 days and that money will not become more plentiful until September. A large percentage of smaller S&ls in Baltimore already are out of the market, and continued demand will drive up rates for those still in the market. In Southern Maryland and on the Eastern Shore, more lenders are requiring higher down payments, up to one-third of the purchase price.

As of last Wednesday, BBR reported that 44 percent of the state's lenders had stopped making loans, up from 37 percent on May 4. Where money is available, the survey quoted interest rates of from 11.94 percent for 95 percent financing of the purchase price (up from 11.5 percent six weeks earlier) to 11.02 percent for 75 percent financing (compared with 10.71 percent). The BBR annual percentage rate averages include private mortgage insurance and points, usually one for the buyer and one for the seller. (A point, payable at settlement, equals 1 percent of the mortgage loan.)

Two "pretty dim" bright spots appeared in Preston's analysis: The Bank of Brunswick is making 20-year loans with 30 percent down at 10 percent, and the Hall Street Building Association in Baltimore has 10 percent money for 30 years, but only up to $25,000.

The situation is somewhat brighter in Montgomery and Prince George's counties, where 59 percent are still in business making 80 percent loans, according to Victor Peeke, publisher of Interest Data Reports. In suburban Virginia, by contrast, 78 percent of the lenders still are making these loans. Somewhat smaller numbers of these institutions are making 95 percent and 90 percent loans. The limits on these loans are generally $60,000 on the 95 percents, and $75,000 on the 90 percents, although a few run as high as $125,000.

Rates on comparable loans tend to be about one-quarter percentage point higher in suburban Maryland than in Northern Virginia because there is more competition on the Virginia side, Peeke said. For 80 percent financing, the average rate this past week in Montgomery and Prince George's counties was 11.36 percent (up from 11.02 percent six weeks before) and 11.14 percent in Virginia (up from 10.80). The rates for 90 percent and 95 percent financing averaged less than one-quarter percentage point higher. Interest Data Reports does not include points or insurance in the annual percentage rates.

Strangely enough, the rate for those lenders not charging points exceeds those who do by only two or three basis points (hundredths of a percent).

In the District, mortgage availability has fallen drastically in the past six weeks. Then, Peeke reported 38 percent of the lenders were doing business on 80 percent loans; last week, only 13 percent were. In May, 5 percent refused to do business except with old customers exclusively, whereas 11 percent did last week. Most of the banks stopped lending some time ago, and the recent change occurred when mortgage money dried up at savings and loans. Two-fifths had stopped by May 10; 70 percent, as of last week.

The drought is being caused by a heavy drain on savings deposits and the government-imposed usury law. For example, savings and loan customers in the District withdrew $50 million more in April than they deposited, almost twice as much as the previous year. In May, the savings outflow was another $10.7 million, and total mortgage loans closed plummeted to $96 million from $117 million a year earlier.

Interest rates are pushing right up against the 11 percent ceiling in the District. As of last Thursday, the average for 80 percent financing was 10.83 percent.

Several members of the D.C. City Council are supporting legislation to increase the D.C. interest rate ceiling to 15 percent because most of the city's financial institutions have halted all mortgage activity in the absence of higher rates when similar lending in the suburbs produces higher yields.

Finance and Revenue Committee Chairman John Wilson (D-Ward 2) is the prime sponsor of the D.C. legislation, which incorporates many provisions of an earlier bill offered by Council member Betty Ann Kane (D-At Large). "Nobody can get any money. It's not something that I want to do. It's something that I'm almost forced to do," Wilson said last week.

One provision of Wilson's bill would eliminate a limit on interest rates for tenant groups trying to purchase their CAPTION: Picture, A custom house in Vienna: Competition creates lower rates in Virginia. John Troha