You know about the favors Congress has done lately for banks, automakers, morticians and oil companies. Now it's the soft drink industry's turn.

Under intense pressure from soda pop makers, Congress is about to grant the highly profitable industry the most sweeping exemption from antitrust laws in 30 years.

The root beer express went sloshing through the House Judiciary Committee yesterday, assuring that the heavily lobbied exemption will soon reach the floor, where passage is regarded as certain.

The action came after the $13-billion-a-year industry uncapped a 36-ounce, family-size lobby effort that congressional sources called almost unprecedented for its audacious effervescence.

The types of drinks available to American soda freaks, their price and who makes them in the future may hinge largely on the antitrust exemption the bottlers are about to win.

Under the exemption, syrup companies would be allowed to continue their practices of prohibiting price andsales competition between bottlers of the same brands. Competition between brands would not be affected by the bill.

The fight goes back to 1971, when the Federal Trade Commission filed complaints against seven syrup companies. The FTC said the territorial licensing arrangements between the companies and their bottlers were unfair methods of competition.

An FTC administrative law judge ruled for the companies, but the commission overruled him in 1978. The case then went to the U.S. Court of Appeals for the District of Columbia, which still has not ruled.

But the bottlers couldn't wait. They turned to Congress for relief.

Orchestration of the campaign to win the exemption is in the hands of the National Soft Drink Association, which represents about 1,700 of the country's 1,900 soda bottlers.

NSDA spared no rhetoric in stirring its members to descend on Congress, mindful that there is at least one bottling company in every congressional district -- a useful foot in the door of persuasion.

The game plan was simple. An NSDA message obtained by The Washington Post directed bottlers to zero in on their legislators, pin them down and force a commitment on the exemption.

"Your congressman knows it is an election year. He must be made to understand that you and your employes need action on his part," the message said. "We need an uproar of objections . . . Only you can bring it about."

The first target was the Senate, where the old trust-buster, Birch Bayh (D-Ind.) took the unusual posture of leading support for the bottlers' exemption. Even odder, he filibustered against the bill late to prevent Howard Metzenbaum (D-Ohio) from adding crippling amendments.

Metzenbaum's lone-wolf effort to stop the bottlers was crushed 89 to 3 when the Senate adopted the antitrust exemption last month.

"It is just a sad commentary," Metzenbaum said the other day about the industry's highly charged lobby campaign.

Bottlers moved quickly in the House, turning the express into a juggernaut. The exemption bill picked up 319 cosponsors and a pattern to break it free from the Judiciary Committee and force a floor vote was quickly achieved.

Pressure became so heavy and the industry's clout so imposing in recent weeks that several key legislators, who declined to be named, reported campaign threats and demands by the bottlers that no amendments be accepted.

One lawmaker was reminded that his state legislature would be reapportioning congressional districts this year. Others were told that appropriate interest would be shown in their relection campaigns.

One senator, on his way home to a funeral, was accompanied by a bottler who did his arm-twisting at 35,000 feet. Phone calls from lobbyists brought three senators running to beat a deadline for a quorum call involving the legislation.

Drew Davis, chief lobbyist for NSDA, agreed that the bottlers have been adamant in expressing their views, but he rejected suggestions that they have used heavy-muscle.

"I don't think we are being heavyhanded," he said. "It is no surprise to me that our members have made their feelings known to Congress. This is viewed as a life-or-death matter by most bottlers."

Davis added last week, "we oppose any amendments to the bill because we don't want it to go back to the Senate. We can't accept any changes, not even a single comma. The legislation needs to come through now because the congressional year is running out."

To make sure the bill would move, the bottlers and their allies in the House put Judiciary Chairman Peter W. Rodino Jr. (D-N.J.) under unusual pressure.

Committee member Sam B. Hall Jr. (D-Tex.) circulated a petition that would discharge the bill from Judiciary even though Rodino had held five days of hearings and had set a date for marking up the bill.

Rodino denounced the discharge move as a circumvention of regular procedures, but he was trapped. Either he would lose control of the bill, or he could lead his committee through the pro-forma step of acting on the measure.

Monday, Rodino's monopolies subcommittee took up the bill. Seven efforts to amend it were defeated. Yesterday, it moved through the full committee with a few changes so minor that the bottlers and their friends only smiled.

Rodino gave assurances that he will get the bill to the floor for final pasage next week or the following week.

Metzenbaum, tired of the issue, has given assurances he won't filibuster the bill when it gets back to the Senate. But he's still angry.

"It is really very simple," he said. "If we provide antitrust exemptions for the soft drink industry, why not do it for everyone?"