Call it hydrotherapy or hedonism, the latest must in bathroom design is the whirlpool tub. It's Washington's answer to the California hot tub -- no luxury home is complete without one.

One can spend as little as $300 for a whirlpool attachment to an existing tub or as much as $6,000 for a heavyduty, heated whirlpool tub with its own separate water heater and filtration system (known in the trade as a "spa").

When Gary Malasky asked architect Kent Abraham to rearrange half of his four-unit Glover Park apartment house into a duplex bachelor's apartment, one big item on his list of wants was an elaborate heated whirlpool. The result was a popped-up third-floor addition, designed exclusively for a room-sized whirlpool bath that seats at least four and holds 550 gallons of water. Malasky, understandably, doesn't treat his whirlpool like an ordinary bathtub -- its 8-by-8-foot dimensions definitely put it in the category of a small indoor swimming pool. Accordingly, there is a filter, regular chlorine treatments, and, for Malasky, a constant 90-degree temperature setting (made possible by a separate furnace), which he hikes up to 104 degrees when he wants to take a restful soak. In addition to the heater, Malasky installed a heavy-dity motor to make the jets of water more powerful. And, to carry this fantasy bath-in-the-sky one step further, he can make the water bubble with the flip of a switch.

Not everyone wants a tub in the sky. Some people prefer to be swirled about in privacy. To satisfy this need, Virginia home builder Fred Lilly always designs a sumptuous master bath, complete with whirlpool tub. Lilly concentrates on the $500,000-plus house market. He believes in putting in every possible option -- including some that most of us haven't even considered.

No one who lives in a Fred Lilly house ever asks, "What on earth took you so long in the bathroom..." Understandably. The room pictured here is 24 by 32 feet. The 5-by-7 foot whirlpool tub by Kohler boasts gold-plated fixtures -- if one is going to indulge oneself, why not go all the way? -- and costs $5,500. There is also a sauna, a separate shower, a bidet and toilet, a loft hideaway, a sofa and chairs and wall-to-wall carpeting in part of the room. The bath is outfitted with what Lilly calls a "morning kitchen" -- a place to have a cup of hot coffee with a small refrigerator and bar sink.

For Lilly, the master bath is designed to be a haven from the hustle and bustle of life. "Most bathrooms are so small," notes Lilly, "that all you want to do is get in, do what you have to and get out." With the two phones, the mini-kitchen, the loft area, the sofas and baths, Lilly has created a luxurious efficiency apartment within his homes. One could easily live out whole days in this sumptuous environment.