The toilet is not something most homeowners want to discuss in much detail, aside from style preferences. Many don't realize that there is another aspect to choosing a toilet: water consumption. According to the EPA, toilets account for approximately 30 percent of indoor water use in the home. The industry water-use standard for toilets has been holding steady at 1.6 gallons per flush (gpf) since 1994, but with 36 states expecting to face water shortages by 2013—without drought conditions—water utilities and state governments are again looking to restrict the water consumption of toilets.

“We're used to thinking of water shortages being traditionally in the West, but states across the country are realizing that better management of their water is something they have to think about,” says Virginia D. Lee, marketing and outreach specialist for the EPA WaterSense program. In some areas, utilities' infrastructure is reaching the end of its useful life and demand for potable water is increasing along with the population while water resources are diminishing in many regions.

Enter high-efficiency toilets, or HETs—toilets that consume 20 percent less water than the industry standard: no more than 1.28 gpf. While installing HETs is not the only solution for reducing water consumption, it is a key step; a single HET can save 4,000 gallons of water per year, some experts estimate.

HETs were originally offered in the American marketplace only by Australian company Caroma. Now most domestic manufacturers have developed models that qualify as HETs, employing a variety of high-efficiency flushing technologies: dual-flush, pressure-assist, single-flush gravity, and flushometer valve (for commercial applications). Some companies offer more than one flush type across their product lines. Dual-flush toilets offer the best of both worlds: a standard 1.6-gallon flush for solids and a .8- or .9-gallon flush for liquid. The water use averages 1.28 gpf, qualifying dual-flush models as HETs.