What was going on when I was born?

The major aqueduct serving Jersey City broke yesterday, cutting off water for several hours until after the flow was rerouted through a backup main. Four-fifths of Jersey City's residents were left with no water or mere trickles, as were residents of Hoboken, Caldwell and Lyndhurst supplied by the Jersey City system. The break occurred at 3 P.M. By 5:20 P.M., work crews had diverted the water, and pressure was beginning to build up. By evening, pressure was reported near normal.

Inmos International P.L.C., Britain's state- owned venture into manufacturing microchips, has proved a success - so much so that the Government of Prime Minister Margaret Thatcher sees an opportunity to sell the company, while the opposition Labor Party argues that it proves the viability of state participation in business. ''To abandon public ownership now would be no more than ideological spite,'' said Peter Shore, the Labor Party's spokesman on industrial matters, during a recent debate on Inmos's future in the House of Commons. As Labor sees it, the Government, venturing where private industry feared to tread, made Britain the only European nation with an independent, domestically owned mass producer of microchips. Nevertheless, the question is not whether Inmos will be sold to private investors, but when and how. The Government sees selling its 75 percent stake in Inmos as the best way to recoup Britain's $88 million direct investment and $47 million in loan guarantees. A sale would also free Inmos to raise the money it needs for further expansion without placing new burdens on Britain's taxpayers.

Air Florida, once the prime success story of airline deregulation, filed a bankruptcy petition yesterday. The carrier's failure was a result of fare wars and new competition in its markets as other airlines also took advantage of the loosening of Government regulation. Minutes after the 11:45 A.M. filing, Air Florida ordered all its planes grounded, except for one returning to Miami from London. Passengers in Miami thronged the Air Florida ticket counters trying to figure out a way to get to their destinations.

''The street buyers of drugs, the street sellers of drugs, are robbers, are muggers, commit burglaries.

The Treasury Department has proposed a broad increase in the power of the Government to collect information about foreign financial transactions, down to such details as the charges made on individual credit cards in other countries. The Treasury contends that the proposal would help it combat drug smuggling. At the same time, more than a dozen of the nation's largest banks and banking concerns, including the Bank of America, the Chase Manhattan Bank, the American Bankers Association and the New York Clearing House, have criticized the plan. Many bankers say the Treasury proposal raises serious constitutional questions and violates the spirit of the Right to Financial Privacy Act. Almost all said it would be unusually costly and would not work. Several suggested it would also violate the privacy laws of several European nations and could raise serious trade problems.

Members of Congress, hospital officials, civil rights advocates and antiabortion groups have reached agreement on principles for treating severely handicapped infants. Six Senators helped negotiate the agreement and intend to bring it forward in the Senate soon after Congress reconvenes July 23. They span the political spectrum, from conservative Republicans such as Orrin G. Hatch of Utah and Jeremiah Denton of Alabama to liberal Democrats such as Alan Cranston of California and Christopher J. Dodd of Connecticut. The senators want to establish the new standard as Federal policy by writing it into the Child Abuse Prevention and Treatment Act of 1974, under which the Federal Government provides money to the states to help children who have been neglected or abused.

LOS ANGELES WHERE but Los Angeles would a restaurant with an unlisted phone number be tolerated or a style of cooking called nouvelle Southwestern be embraced? When it comes to show business, movies aren't the only game in this town. As ticket holders for the Olympics, which start late this month, and other visitors will discover, restaurants here also have a flair for the dramatic. It can be seen in the decor, which often competes with the food for attention, and it can certainly be tasted. Experimentation in restaurant kitchens is a way of life. The results, as might be expected, are a mixed blessing. Wonderfully inventive dishes coexist with those that tickle the funny bone instead of the palate. Certain patterns emerged from a recent 8-day visit to 15 restaurants here. For one thing, much of what is interesting, both good and bad, is found in newer restaurants, many of them just a year or two old.

The General Motors Corporation took another major step today in the sweeping reorganization of its North American automotive operations by announcing it had completed the breakup of its historic Fisher Body division. G.M. said that eight parts-making plants of the Fisher division had been combined with the Guide division, a producer of headlights and plastic parts, to form the Fisher Guide division. Other plants formerly operated by Fisher have been split among the two new automotive groups in the company - the Chevrolet-Pontiac and G.M. of Canada group and the Buick-Oldsmobile-Cadillac group - and other components operations.

Tiny Luxembourg, a maverick in the tightly regulated world of European broadcasting, is planning on a big role in the multibillion-dollar market now emerging in Europe for commercial television. Prime Minister Pierre Werner announced details of a project in May to put an American-made television satellite into orbit by 1986 to beam as many as 16 commercial television channels into European households. It would send the channels either to large central antennas that feed cable television networks or to households equipped with small dish antennas. The announcement sent shock waves through other European capitals, where officials are spending hundreds of millions of dollars to develop domestic satellites to feed programming into cable networks.

Twelve months into her tour as a Peace Corps volunteer, Jennifer Lynn Rubin, a 23-year-old from Oneonta, N.Y., seemed finally to have come to terms with the loneliness of being the sole volunteer in the village of Defale, population 500, in the West African country of Togo. Her letters home told of her trouble adjusting to her relocation from upstate New York. In some letters, Miss Rubin repeatedly mentioned a villager she had befriended, a 19-year-old woman named Gieselle who helped her adjust to the culture in northern Togo, a former French colony. On June 11 Miss Rubin was bludgeoned to death in her home, and the police in Togo have charged Gieselle with the murder. The police say they believe Miss Rubin was killed in revenge for telling Gieselle's father that she had stolen clothing and other items from Miss Rubin's home. Gieselle's last name has not been made public.

A report in the Business People column yesterday about the new senior vice president of the Federal Reserve Bank of New York misidentified him. He is Frederick C. Schadrack.

well, as the Fourth of July. This fine old tradition goes back at least to the early years of the 19th century, perhaps even to 1776, when Americans celebrated, with public noise and acclamation, the birth of a nation. There was a time when you could tell what part of the country you were in by the food that was served at the Fourth of July picnic, but that is no longer an entirely reliable indicator. These days, as a recent informal survey of picnicking habits around the country found, there are New England clambakes in the Texas Panhandle, salmon in the Recipes are on page C5. Southwestern desert, barbecues on the shores of Lake Michigan and Southern-style backyard pig roasts in Queens.