Remember when the federal government passed the law requiring that all new residential toilets sold in the U.S. use no more than 1.6 gallons of water per flush? There was a great deal of consumer criticism that the lower-flush toilets performed poorly, but the law stuck, manufacturers improved the products, and everything turned out fine.

Today 1.6-gallon toilets seem antiquated and, to many in the industry, a little wasteful, especially since toilet flushing accounts for most of the 80 gallons to 100 gallons of water the average U.S. citizen uses per day.

Perceptions began to change when the Australian government approached manufacturer Caroma to see how the company could help with water conservation, says Derek Kirkpatrick, Caroma’s North America general manager. That technology was then brought to the U.S. Today, the ubiquitous dual-flush toilet uses a standard 1.6 gallons for a general flush and a second option that uses less water. Almost every toilet manufacturer offers one, in combinations that include 1.6/1.1 gallons to 1.28/0.6 gallons. Caroma makes only dual-flush toilets, and manufacturers such as Duravit, TOTO USA, and Kohler are also major players in the category.

Dual-flush units qualify for WaterSense certification, a voluntary EPA program to help consumers reduce water consumption. Certified high-efficiency toilets use 20 percent less water than standard products. But dual-flush is not the only way to conserve water. Kohler, for example, offers two—the Highline Pressure Lite and the San Raphael—that flush with only 1 gallon, and Foremost Groups offers one as well. The company that takes the prize for ultra–low-flow is Niagara Conservation in Fort Worth, Texas, whose single-flush Stealth uses only 0.8.

It appears, though, that ultra–low-flow toilets have some challenges to overcome. For one, the jury is still out on whether they use too little water in some situations. “There is a limitation on how low we can go,” Kirkpatrick says. “At 0.8 gallons, the drain line could be affected. We’re not sure if 0.8 gallons is enough to take waste out of an old house. There could be roots in the line and the slope of the pipe could be less than ideal.” This fear might be justified. San Francisco’s push for low-flow toilets has resulted in more sludge backing up inside the sewer pipes, creating the smell of rotten eggs.

Some low-flow toilets also have a small water area, which could lead to markings in the bowl. Tim C. Schroeder, president of Duravit USA, explains that traditional toilets in the U.S. have a restricted flap and a large water area. But low-flow toilets, he says, typically use a wash-down system and have an unrestricted flap but a smaller water area. High-efficiency toilets do save water, but be sure to consider all the options when making a purchase.

Learn more about markets featured in this article: Dallas, TX.