Americans are used to ordering things ranging from french fries to popcorn in small, medium or supersize. Now those same decision-making skills may become useful in the bathroom, thanks to an innovative plumbing technology: dual-flush toilets. The new gizmos are the industry's latest attempt to help reduce water usage, a movement that hasn't always gone smoothly. The last big toilet makeover came more than a decade ago, when the U.S. government decreed that new toilets should use just 1.6 gallons of water per flush, down from the 3.5-gallon standard that had ruled the industry for decades. But consumers complained that it often took two or more flushes to clear the bowl; so many people preferred the old toilets that some plumbers imported them illegally from Canada. "We're still getting complaints about people not happy with the performance," says Bill Gauley of Veritec Consulting. The dual-flush toilets, which have been used for years in Australia and parts of Europe, rely on a simple concept to increase efficiency: it takes less water to flush urine than it does to eliminate what the industry euphemistically calls "bulk waste." So dual-flush toilets incorporate two flush buttons, or a handle that moves in two directions. The "long flush" uses 1.6 gallons; the "short flush" uses as little as half that amount. In a Canadian study, replacing old toilets with dual-flush models reduced a household's water usage by nearly 12,000 gallons annually. For years a single manufacturer sold a dual-flush toilet in the United States, but today there are six models on the market, according to Yorba Linda, Calif., water consultant John Koeller, with four new ones expected in stores by next year. Kohler, the largest U.S. toilet maker, introduced its $270 Sterling Rockton model with Dual Force flushing in April. Water authorities in some of the drought-plagued Western states hope home builders catch on.