The once-humble bath has become the showcase of the house.

Whirlpool tubs, steam showers, skylights, brass fixtures, marble floors - and plenty of space - all add up to a room that spells luxury." . . . We're not seeing many homes being built without whirlpool tubs," said Jackie Huckaby of Clearwater Baths and Spas of Memphis. "They're the big thing. Baths have become very luxurious and much larger. The master bedroom and bath are often the fanciest rooms in the house, and sometimes the largest."

"Architects used to win awards for putting a bath in the smallest possible area," said Ken Terry, a designer for Hill Plumbing in Memphis. Now the bath is more often than not a large combination dressing room-sitting room-bath, he said.

"The whirlpool is no longer an amenity," Terry said. "I'd place it where the dishwasher was a few years ago. We've done few baths without it."

Tom Nickels of Royal Baths Manufacturing Co. in Houston said about 10 percent of homes now have whirlpool tubs, but he predicts that figure will reach 80 percent by the year 2000.

"We're seeing a steady growth in whirlpool tubs," Nickels said. "They're not only a luxury, they're therapeutic."

A major trend in whirlpool tubs, he said, is toward the longer, 6-foot tub. "People who have had a 5-foot are taking that out and putting in the 6-foot."

Ed Richmond, president of Americh in North Hollywood, Calif., and Charlotte, N.C., sees an emphasis on larger whirlpool tubs across the country. "Customers want them large enough for two people," he said. "They're highlighting the tub and making it the centerpiece for the bath."

People today are treating the bath as a major room in the house, Richmond said. "They're spending more time in there and investing more money to show it off."

He noted that a majority of the baths "bring more of the outdoors in" with the use of skylights and other open areas.

The ultimate bath is one with real marble for the whirlpool, deck, splash area, vanity and floor, said John Saunders, a residential estimator for Tri-State Tile and Marble Co. in Memphis. But man-made marble is the most common, he said. "You may not feel like you're in Buckingham Palace, but the man-made marble is still stunning," he said.

Another significant trend, says Saunders, is the bath with both a tub and shower stall. "It can be that simple, or you can take it a step up to where the tub is a whirlpool and the shower stall is a steam bath."

Terry says an established European concept - the bidet - has crossed the Atlantic. "When space allows for an extra fixture, I think it will become a natural part of bath renovation in the next five years," he said.

He said the typical bath renovation, including a whirlpool tub, separate shower, ceramic tile, new cabinets and fixtures, costs between $15,000 and $18,000.

Colors in the bath run the gamut. "We're seeing colors like dusty rose, platinum, blue and bone," Mrs. Huckaby said. Most of the luxury baths have brass rather than chrome fixtures. "There are even colored faucets, like ruby, onyx, champagne and bone," she said.

"Some people want to get real distinctive with colors, but they also need to consider resale," said Saunders. "They may love hot pink, but it might not sell."

Terry has a word of caution about whirlpool tubs. "A lot of those being installed in new homes are not approved by the NSPI (National Spa and Pool Institute) because they do not have a 100 percent drain-down system. That means you can end up with a couple of gallons of another person's dirty bath water in the tub."