Bathtubs wear out every 20 years, on average. But it's not the old tub wearing out that's driving demand for walk-in tubs.

Walk-in tubs ? acrylic or gel-coated fiberglass ? are custom-manufactured personal bathtubs. The most important feature, and the one that makes them distinct, is a door on the side that closes to form a water-tight seal. The idea, and the attraction, is that someone can step into a bathtub without having to lift their leg 14 to 18 inches.

The ability to step right in makes walk-in tubs appealing to homeowners 55 or over ? especially to those with limited mobility. The largest percentage of falls and other injuries in the home occur in the bathroom or on stairs, many connected to conventional bathtubs. "The No. 1 reason someone enters a nursing home," says Rob Buete, CEO of Safety Tubs, a Texas manufacturer of walk-in tubs, "is their inability to bathe themselves." Pat Krushen, advertising and marketing director for Safety Bath, a Canadian manufacturer, agrees. She calls "the dignity issue" the primary factor driving market demand.

Must-Have Product

Walk-in tubs are all over the place. Homeowners can buy them online as well as in retail outlets such as Costco. Paul Gordon, president of Golden Gate Enterprises, a home improvement and remodeling company in Castro Valley, Calif., says that such tubs have been around for a long time ? actually manufacturers have been making and marketing them for at least 20 years ? but that demand has noticeably grown during the last two or three years.

For some companies, taking on walk-in tubs has been a natural extension of their move into acrylic tub liners. "We've been doing bath remodeling for about a year and a half," says Rob Levin, president of Statewide Remodeling, in Grand Prairie, Texas. "And we kept running into it. People kept asking about [walk-in tubs] and we didn't have a product to show them. So we brought it into our line." Levin says that his company has, since last fall, installed about 50 walk-in tubs.

Home improvement companies like a product that is, as Wayne Gerber, of Seabridge Bathing, another Canadian manufacturer, calls it, a "need-to-have" item. And the attraction works both ways. Safety Tubs and other manufacturers have recently sought out home improvement companies for their in-home sales expertise, access to financing, and their marketing prowess in generating leads and then sales.

Getting the tub installed, says Mike Marohnic, owner of California Doors & Windows, in San Diego, is "just basic plumbing and carpentry." Marohnic's company offers gel-coated fiberglass models."A lot of our dealers have it down to a one-day install," Buete says.