The Environmental Protection Agency yesterday proposed relaxing water pollution standards for 18 different industries, a move calculated to save industry an estimated $200 million "without any significant adverse impact on water quality."

Although EPA administrator Douglas M. Costle told reporters the action was "in the works" long before White House inflation Czar Robert Strauss attacked environmental regulation as "inflationary" last year.

The action also is expected to prevent possible forced closings of several small plants - particularly small plants in the food processing area - which would face severe hardship under the existing regulations.

The move came after the EPA received permission last year from Congress to review its existing water pollution requirements for 1984. Under present rules, the EPA requires all plants to install the best available pollution-control equipment by 1983.

After the authority was granted last year, EPA surveyed proposed water standards for 93 different industries, pertaining to discharge of conventional pollutants like dirt and organic debris.

The review did not include any attempt to cut back on environmental standards involving toxic pollutants.

The proposed limitations in 18 of the 93 industries were eventually judged by the EPA to be unreasonable.Limitations in an additional 18 of the industries have been suspended pending further review.

"We feel the remaining limitations, after examination, were reasonable and will be retained," Costle said.

Interested parties will have 90 days to submit comments on the proposed changes, which will be published in the Federal Register shortly.

EPA official Swept Davis said the industries that will benefit most from yesterday's action are fruit and vegetable canners, crab, shrimp and other seafood processors, glass producers, slaughter houses and packing houses and certain metal producers.

According to Davis, some 250 of an estimated 350 fruit and vegetable processors across the country will benefit from the proposed relaxation. That industry alone is expected to save $75 million.

Davis said most of the companies that will be affected "are already cleaning out 98 percent of the pollutants in their water discharge. But the new rules, which would have raised that percentage one or two points, would require the same amount of money that it cost to clean out the first 98 percent."

"In these cases," Davis said, "we are willing to say that they have done enough."

In all, the existing requirements would have cost all industry $500 million by 1984. But, according to Costle the relaxation announced yesterday drops that estimate to $300 million - "a 40 percent savings."

Some plants, for example, will not now have to install costly water treatment facilities.

In some states, however, Davis emphasized, the regulations will be tightened by state agencies. The ENA felt, however, that there "is no longer a need for a nationwide unified standard," which he said created "unneeded inefficiencies in areas where enough has already been done."

Despite Costle's statement that the water pollution study had been underway for some time prior to the beginning of the White House anti-inflation campaign, he acknowledged that the agency now has 40 ongoing projects exploring regulatory refrom measures that could reduce the inflationary impact of regulation.

"We are asking the question, 'What is the inflationary impact?' on all of our projects" he said.

"If we can get the job done for 50 cents or for a buck, we'll get it done for 50 cents," he said.

National Food Processers Association spokesman Jack Cooper praised the EpA proposals.

"The requirements were overly burdenson and unrealistic," Cooper said. "We have been trying to get them changed for along time. They would have required us to pay unreasonable charges for little or no benefit."

Cooper said the consumer would be the winner in the long run. "The pressure to increase prices will be reduced because the cost of production will now be less," he said.

Frank Sebastian, president of the Water and Waste Water Equipment Manufacturer's Association and president of Envirotech, a Menlo Park, Calif. firm that builds water pollution control equipment, said his industry will probably not be hurt too much by the ruling.

"But overall," he said, "we believe that the benefits from environmental regulation exceed the costs, and we favor more tax incentives that would compensate companies that do clean up - because many of the benefits of cleaning up are outside the company's realm, even though they get hit with the costs."

Costle contended that environmental regulation actually has little or no inflationary impact.

"People don't calculate the benefits when they look at the costs of environmental regulation, because they can't - they don't know how," he said at the press conference. "And we have found that the American public, according to recent polls, is willing to pay the price to improve the quality of life."

In two other related announcements, the EPA said it would be revamping its adjudicatory hearing process to make it "less of a hassle," and to cut the cost to a company requresting a hearing about 30 percent.

And, the EPA said it would also be overhauling the regulations for processing permit applications.