The Rainbow vacuum is unique because it uses water to trap dirt vacuumed from surfaces. A reservoir containing about two quarts of water sits beneath the patented "Separator", a device that agitates the water and traps dirt in it, effectively power-washing the air. Atop the Separator sits a powerful motor. The current model, dubbed the e2 and in production since 2000, accepts an assortment of accessories such as a power-driven beater head, long-hose stair and upholstery nozzle, carpet-cleaning system, and a wet-vac head for bare floors.

The e2 can double as a rather noisy air purifier using high or low speed settings. More commonly, it is placed under a plastic tent along with pillows. The e2's water-washing air filtration system sucks dust, pollen, and even tiny mites out of the pillows. Rexair sells additives for the water reservoir that freshen and scent the air expelled by a Rainbow vacuum. A sprayer attachment uses the blower outlet to spray water and fertilizer on houseplants, or to spray household cleaners on major projects such as furniture and walls. The dusting brush can be used on delicate china, lampshades, or even the family pet. Using the un-powered nozzle head to clean up wet spills makes the Rainbow uniquely versatile.

All is not peaches-and-cream for Rainbow vacuums. They're heavy; the e2 weighs 32 pounds! While it does an excellent job of trapping the dirt it picks up, reviewers have been split on how well it picks up dirt for its premium price. (My teenaged son concurred; he was glad to see the old Rainbow go.) A new e2 costs well over $1,000, and buying accessories is like buying performance car parts.

On the other hand, Rainbow vacuums are famously rugged and reliable, ranking among the vacuums with fewest repairs. Indeed, a Rainbow vacuum repairman is just as lonely as the proverbial Maytag repairman! That vintage 1950s Rainbow of mine needed only two repairs in almost half a century. Perfectly serviceable Rainbows from decades past are plentiful on eBay, Craigslist, and other secondary markets for a fraction of a new machine's cost.

Consumer Reports rates the Rainbow vacuum among its top picks for pet hair pickup. It notes the Rainbow vacuum is rather noisy and does not far outshine other high-end vacuums on carpets. The unique, water-enabled versatility of the Rainbow vacuum earn it an editor's choice award.

No other vacuum has been the centerpiece of a work of fiction (if you don't count marketing hype). In "The Vacuum She Left", a housewife falls in love with her Rainbow vacuum and ends up running off with the man who sold it to her. Now that's true love!