Once in a while you come across a warm, sensible service performed by a federal government agency that, if widely known, would help counteract a bit of the bad publicity the Washington bureaucracy regularly gets. This is a story about such a service.

Last year, the General Services Administration sent free cases of scotch, rye, vodka and rum -- 39 gallons in all -- to the Franciscan Sisters of the Poor. The sisters run the Frances Schervier Home and Hospital for the aged in New York City, and use the liquor for the regular "happy hour" held every Wednesday afternoon for the home's 364 residents.

Also last year, GSA took credit for delivery of 55.2 gallons of free Canadian beer to the St. Bonaventuire Monastery in Detroit. The Capucin Charity Guild, which operates free meal and counseling programs from a community center located on the monastery's property, used the beer for its summer and Christmas staff parties and for several dinners for guild members who contribute funds that support the programs.

GSA also donated 227 gallons of assorted liquor -- mostly beer, with some rum, whiskey and wine -- to the Glen Lake State Sanatorium in Minnetonka, Minn. Doctors prescribe the beer and spirits for some of the elderly patients, to keep their time at the sanatorium somewhat homelike. On holidays, the wine is also used at dinner.

Overall, in fiscal 1980, GSA donated more than 500 gallons of liquor, wine and beer to 18 nonprofit institutions around the country, most of them homes for the elderly. And, according to the April 2 Federal Register (page 20014), GSA is prepared to sign up more prospective recipients.

By now you must be wondering the obvious: where does this free GSA liquor come from?

The answer is that, for the most part, the Customs Service seized it for nonpayment of duty. Anytime customs or the alcohol unit of the Treasury Department takes in more than five gallons, according to the rules, GSA must be informed and the haul be made available for disposal.

GSA then gives other government agencies first crack at it, and what's left is offered for donation to nonprofit organizations.

In fiscal 1980, according to GSA, government agencies took in 1,063 gallons of seized liquor; the State Department, at 589 gallons, wound up with the lion's share. It went primarily, sources said, to stock Blair House for official vistors. During past administrations, the White House was a big participant in the program, but not at all over the past four years under Jimmy Carter, who refused to serve hard liquor to his guests.

The liquor is not just handed out to anyone who asks for it. The Cabinet secretary or agency director involved must sign a statement for GSA saying the beverages will be used in the course of official business. And the nonprofit agencies must certify in writing that "all foreited distilled spirits, wine, or malt beverages donated to the applicant will be used only for medicinal purposes, and only in connection with the official work of the applicant."

If you want to join the 1,800 other nonprofit organizations on GSA's free-liquor list from which next year's lucky few will be chosen, and are willing to sign the certification agreement, call (202) 472-5212 for information.